476 terms

iGCSE Chemistry: Y10 End of Year - core

STUDY
PLAY

Terms in this set (...)

Describe the arrangement and movement of the particles in a liquid
Particles are close together but irregular. The particles are free to move.
Describe the arrangement, movement and energy of the particles in a gas
Particles are far apart and there are no forces between them. Energy is high. The particles move quickly and freely.
Describe the arrangement, movement and energy of the particles in a solid
Particles are close together and regularly packed. Energy is low. The particles vibrate around a fixed point.
Draw 3 particle diagrams to show the arrangement of particles in a solid, liquid and gas. Draw arrows between them and label boiling, condensing and freezing
X=boiling, Y=condensing, Z=freezing
What happens when something condenses?
Condensation is the change of state when a substance cools from gas to liquid
What happens when something evaporates?
Evaporation is the change of state when a substance heats up from liquid to gas
What happens when something melts?
Melting is the change of state when a substance heats up from solid to liquid
Define the term Saturated Solution
When no more solute can dissolve in a solution
Define the term Solute
The substance that dissolves in a solvent, forming a solution
Define the term Solution
The mixture of a soluble solute and a solvent
Define the term Solvent
The liquid which dissolves a solute
(Triple only) Define the term Solubility
A measure of how much solute dissolves in a solvent (in g per 100g)
(Triple only) What is the unit of solubility?
g of solute per 100g of solvent
(Triple only) A graph shows the solubility of sodium chloride in water at 50°C is 34g/100g. At that temperature, what mass of sodium chloride will dissolve in 200g water?
68g
(Triple only) A graph shows the solubility of sodium chloride in water at 50°C is 34g/100g. At that temperature, what mass of sodium chloride will dissolve in 50g water?
17g
(Triple only) State 2 ways in which more solute could be dissolved in a saturated solution
Heat the solution. Add more solvent.
(Triple only) What observation would be made if a saturated solution is cooled?
Solid would come out of solution
How many different elements are there in Be(OH)₂ ?
3
What is meant by the term compound?
A compound is a substance that contains two or more elements chemically joined together in fixed proportions
What is meant by the term element?
An element is a substance made of only one type of atom
What is meant by the term mixture?
Different substances in the same space, but not chemically combined.
Describe how pure salt can be obtained from rock salt
1) Grind rock salt into a fine powder. 2) Add powder to hot water and stir to dissolve salt. 3) Filter mixture. Salt solution passes through the filter paper leaving behind the sand. 4) Boil filtrate to evaporate some of the water. 5) Leave saturated solution to cool so that crystals of salt form. 6) Filter cold mixture to separate the crystals from the remaining solution.
Draw a conical flask
Draw a diagram to show equipment used in simple distillation
Draw a funnel
Draw a mass balance
Draw an evaporating basin
Explain how fractional distillation is used to separate a mixture of different liquids
The different liquids have different boiling points
For what is the process of filtration used?
To separate an insoluble solid from a liquid
For what is the process of fractional distillation used?
To separate a mixture of different liquids that have different boiling points
For what is the process of simple distillation used?
To separate a liquid from a solution
For what is the separation technique of crystallisation used?
To obtain a dissolved salt from a salt solution
For what is the separation technique of paper chromatography used?
To separate various dyes from a mixture of dissolved dyes
State the method used to obtain kerosene from crude oil
fractional distillation
State the method used to obtain red food dye from a mixture of food dyes
paper chromatography
State the method used to obtain sand from a mixture of sand and water
filtration
State the method used to obtain solid copper sulfate from aqueous copper sulfate
crystallisation
State the method used to obtain water from salt water
simple distillation
Explain how a chromatogram shows that different dyes are different from each other
Each dye has components which rise to a different height on the paper
In paper chromatography if several dyes rise up the paper, why might another dyes not rise?
The other dye is insoluble in the solvent being used
In chromatography, what are the minimum and maximum possible values for an Rf value?
Minimum=0. Maximum=1.
What is the formula for calculating an Rf value?
Distance the dye has travelled divided by distance the solvent front has travelled. Both measured from the baseline.
In a paper chromatography experiment using a flammable solvent, why might a lid be used? (2)
To prevent the solvent from evaporating, and to reduce the risk of the solvent catching fire
In paper chromatography, the paper is position so it touches the solvent, but why is the paper position so baseline onto which dyes are placed is above the solvent?
So the dyes don't simply dissolve into the solvent
In paper chromatography, why is the baseline drawn in pencil?
Pencil will not dissolve in the solvent, but if ink were used instead it might dissolve and interfere with the results of the chromatography.
What is meant by the term atom?
An atom is the smallest part of an element
What is meant by the term molecule?
A molecule is made of a fixed number of two or more atoms covalently bonded together
What is the total number of atoms in the formula Be(OH)₂ ?
5
What is meant by the term atom?
An atom is the smallest part of an element
Explain why atoms are neutral
The numbers of electrons and protons are equal
State the mass and charge of a neutron
Neutron: mass=1, charge =0
State the mass and charge of a proton
Proton: mass=1, charge=+1
State the mass and charge of an electron
Electron: mass=almost zero, charge=-1
State the particle that is found in the shells orbiting the nucleus
Electrons
State the particles that are found within the nucleus of an atom
Protons and neutrons
How many neutrons in a typical atom of fluorine?
10
How many protons in a fluorine atom?
9
Tritium, an isotope of hydrogen, has a mass number of 3. How many neutrons does an atom of tritium contain?
2
What are isotopes?
Isotopes are atoms of the same element (same number of protons) but with a different number of neutrons (different mass)
What is a mass number?
Mass number is the number of protons plus the number of neutrons in an atom
What is an atomic number?
The atomic number is the number of protons in an atom
What is meant by the term relative atomic mass, Aᵣ?
The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12
What is the atomic number of a chlorine atom?
17
What is the relative atomic mass (Aᵣ) of a potassium atom?
39
How many neutrons in a typical atom of fluorine?
10
How many protons in a fluorine atom?
9
What is a mass number?
Mass number is the number of protons plus the number of neutrons in an atom
What is an atomic number?
The atomic number is the number of protons in an atom
What is meant by the term relative atomic mass, Aᵣ?
The average mass of an atom of an element, relative to 1/12th of the mass of an atom of carbon-12
What is the atomic number of a chlorine atom?
17
What is the relative atomic mass (Aᵣ) of a potassium atom?
39
A sample of bromine contained the two isotopes in the following proportions: bromine-79 = 50.7% and bromine-81 = 49.3%. Calculate the relative atomic mass of bromine
((79x50.7)+(81x49.3))/100 = 79.99
A sample of carbon contained 98.90% carbon-12 and 1.10% carbon-13. Calculate the relative atomic mass of carbon
((12x98.90)+(13x1.10))/100 = 12.01
How are elements arranged in the periodic table?
in order by atomic number
On the Periodic table what is the meaning of the word Group?
A Group is a vertical column of similar elements
On the Periodic Table what is the meaning of the word Period?
A Period is a horizontal row of elements
How many electron shells do the elements in the third period have?
3
How many electrons can the first, second and third shells hold?
First 2, second 8, third 8
How many electrons in a calcium atom?
20
How many electrons in the outer shell of group 7 elements?
7
Write the electronic configuration of potassium
2,8,8,1
Are metal oxides acidic or basic?
Basic
Are non-metal oxides acidic or basic?
Acidic
If an element doesn't conducts electricity, is it a metal or a non-metal?
Non-Metal
If an element doesn't conducts electricity, is it a metal or a non-metal?
Non-Metal
Where are non-metals found on the periodic table?
At the top right, plus hydrogen
Why do elements in the same group of the periodic table have similar chemical properties?
Elements in the same group of the periodic table have the same number of electrons in their outer shell
Explain, in terms of the arrangement of electrons in its atoms, why neon is very unreactive
Neon has 8 electrons in the outer shell, so it is full. Therefore it does not easily gain or lose electrons
What are the elements in group 0 called?
Noble gases
What is special about the elements in group 0?
They are very unreactive (because they have full outer electron shells)
What do each of the following state symbols represent: (s), (l), (g), (aq)
(s) - solid. (l) - liquid. (g) - gas. (aq) - aqueous (in solution)
Calculate the relative formula mass(Mr) of ammonium nitrate (NH₄NO₃)
80
Calculate the relative formula mass(Mr) of calcium hydroxide (Ca(OH)₂)
74
Calculate the relative formula mass(Mr) of hydrated copper (II) sulfate (CuSO₄.5H₂O)
249.5
What are the units for amount in Chemistry?
Moles
What is the meaning of the word mole in Chemistry?
A mole is the amount of a substance found in its relative formula mass in grams (e.g. in 24g of Magnesium)
Using relative atomic mass (Aᵣ) and relative formula mass (Mᵣ), complete the following expression: amount (in moles) =
mass / Mr
Using relative atomic mass (Aᵣ) and relative formula mass (Mᵣ), complete the following expression: mass =
amount (in moles) x Mr
Using relative atomic mass (Aᵣ) and relative formula mass (Mᵣ), complete the following expression: Mᵣ =
mass / amount (in moles)
What mass of calcium bromide will fully react with 71g of chlorine?
200g
What mass of carbon dioxide is produced when 24g of carbon undergoes completely combustion?
88g
In the thermal decomposition of calcium carbonate, we might expect 50g of calcium carbonate to produce 28g of calcium oxide. If instead only 24g of calcium oxide is produced, what is the yield?
86%
State the expression for calculating % yield.
% yield = (actual amount of products/theoretical amount of products) x100
1.170 g of CoCl₂.xH₂O gave a residue of 0.641 g on heating. Find x.
6
7.485 g of a hydrated copper(II) sulphate CuSO₄.xH₂O was heated producing 4.785g of anhydrous copper(II) sulphate. What is the formula of the hydrated salt?
CuSO₄.5H₂O
State the steps for calculating empirical formula
1) mass/Ar. 2) divide by the smallest. 3) Give the ratio has a whole number. 4) State final empirial formula
What is the empirical formula of an alcohol with the analysis; 52.2% C, 13.0% H and 34.8% O?
C₂H₆O
What is the formula of a compound in which 0.48 g of carbon combines with 0.08 g of hydrogen and 0.64 g of oxygen?
CH₂O
Work out the empirical formula of an oxide of chlorine contains 7.1 g of chlorine and 1.6 g of oxygen.
Cl₂O
State the steps for calculating empirical formula
1) mass/Ar. 2) divide by the smallest. 3) Give the ratio has a whole number. 4) State final empirial formula
Tungsten has the chemical symbol W. Suggest the chemical name of WO₃.
tungsten oxide
What is the empirical formula of an alcohol with the analysis; 52.2% C, 13.0% H and 34.8% O?
C₂H₆O
What is the formula of a compound in which 0.48 g of carbon combines with 0.08 g of hydrogen and 0.64 g of oxygen?
CH₂O
Work out the empirical formula of an oxide of chlorine contains 7.1 g of chlorine and 1.6 g of oxygen.
Cl₂O
What is meant by the term empirical formula?
A chemical formula that shows the simplest ratio of the numbers of atoms in a compound
What is meant by the term molecular formula?
A chemical formula that shows the actual numbers of the different types of atoms in a molecule
A compound that contained 24.24% Carbon. 4.04% Hydrogen and 71.72% Chlorine and has a relative molecular mass of 99. Calculate the empirical formula and the molecular formula.
Empirical formula is CH₂Cl. Molecular formula is also C₂H₄Cl₂
An oxide of nitrogen contains 26% nitrogen and 74% oxygen and has a relative molecular mass of 108. Find the empirical and molecular formulae for the oxide.
Empirical formula is N₂O₅. Molecular formula is also N₂O₅
(Triple only) A sample of hydrogen chloride gas has a volume of 48 dm³. What amount of hydrogen chloride is this?
2 moles
(Triple only) State the expression for calculating molar volume of a gas.
Molar volume = amount (in moles) x 24 dm³ or 24,000 cm³
(Triple only) What is the meaning of the term Molar Volume?
The volume of 1 mole of gas at r.t.p is called the molar volume (24dm³ or 24000cm³)
(Triple only) What volume does 0.5 moles of ethene gas occupy (at rtp)
12 dm³
(Triple only) What volume does 3 moles of carbon dioxide gas occupy (at rtp)?
72 dm³
To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is a lid lifted from time to time?
To allow oxygen in so the magnesium fully reacts
To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is a lid used?
To stop the escape of magnesium oxide smoke
To determine the formula of a metal oxide by combustion, magnesium is heated in a crucible. Why is the crucible is cooled, weighed, reheated, cooled, re-weighted, and so on?
By repeating till 2 consecutive masses are recorded, we know that the magnesium has all reacted
All the atoms in group 1 have 1 electron in their outer shell. What charge ions do they form?
+1
All the atoms in group 3 have 3 electron in their outer shell. What charge ions do they form?
+3
All the atoms in group 5 have 5 electron in their outer shell. What charge ions do they form?
-3
All the atoms in group 7 have 7 electron in their outer shell. What charge ions do they form?
-1
Describe, in terms of electrons, the formation of sodium chloride
An atom of sodium loses one electron. An atom of chlorine gains one electron
State the electron configuration of the fluoride ion
2,8
What is the formula of the calcium ion?
Ca²⁺
Zinc phosphide, Zn₃P₂ is an ionic compound. The formula of the zinc ion is Zn²⁺. Deduce the formula of the phosphide ion
P³⁻
If copper chloride has the formula CuCl₂, what is the formula of the copper ion?
Cu²⁺
If iron chloride has the formula FeCl₂, what is the formula of the iron ion?
Fe²⁺
If iron chloride has the formula FeCl₃, what is the formula of the iron ion?
Fe³⁺
If iron oxide has the formula FeO, what is the formula of the iron ion?
Fe²⁺
State the formula for the copper (II) ion
Cu²⁺
State the formula for the iron (II) ion
Fe²⁺
State the formula for the iron (III) ion
Fe³⁺
State the formula for the lead (II) ion
Pb²⁺
State the formula of the ammonium ion
NH₄⁺
State the formula of the carbonate ion
CO₃²⁻
State the formula of the hydroxide ion
OH⁻
State the formula of the nitrate ion
NO₃⁻
State the formula of the silver ion
Ag⁺
State the formula of the sulfate ion
SO₄²⁻
State the formula of the zinc ion
Zn²⁺
State the formula of the zinc ion
Zn²⁺
If iron chloride has the formula FeCl₂, what is the formula of the iron ion?
Fe²⁺
If iron chloride has the formula FeCl₃, what is the formula of the iron ion?
Fe³⁺
State the formula for the copper (II) ion
Cu²⁺
State the formula for the iron (III) ion
Fe³⁺
State the formula of the hydrogen ion
H⁺
State the formula of the silver ion
Ag⁺
State the formula of the zinc ion
Zn²⁺
What is the formula for aluminium chloride?
AlCl₃
What is the formula for calcium nitrate?
Ca(NO₃)₂
What is the formula for iron (III) bromide?
FeCl₃
What is the formula for lithium carbonate?
Li₂CO₃
What is the formula for silver carbonate?
Ag₂CO₃
What is the formula for strontium phospide?
Sr₃P₂
What is the formula for aluminium chloride?
AlCl₃
What is the formula for aluminium oxide?
Al₂O₃
What is the formula for potassium sulfide?
K₂S
What is the formula for sodium phosphide?
Na₃P
Draw a dot and cross diagram to show the arrangement of electrons in each of the ions in potassium oxide, K₂O
Draw a dot and cross diagram to show the arrangement of electrons in each of the ions in sodium chloride, NaCl
How can atoms get a full outer shell?
Either the transfer (ionic) or sharing (covalent) of electrons
Explain the term ionic bond
An ionic bond is the strong electrostatic attraction between oppositely charged ions
When are ions attracted to each other?
When the ions are oppositely charged
Describe the formation of a covalent bond
The sharing of a pair of electrons between two nuclei
Give the definition of a covalent bond
Strong electrostatic attraction between a shared pair of electrons and two nuclei
Draw a dot and cross diagram to show the covalent bonding in a molecule of ammonia, NH₃
Draw a dot and cross diagram to show the covalent bonding in a molecule of carbon dioxide, CO₂
Draw a dot and cross diagram to show the covalent bonding in a molecule of chlorine, Cl₂
Draw a dot and cross diagram to show the covalent bonding in a molecule of hydrogen chloride, HCl
Draw a dot and cross diagram to show the covalent bonding in a molecule of hydrogen, H₂
Draw a dot and cross diagram to show the covalent bonding in a molecule of methane, CH₄
Draw a dot and cross diagram to show the covalent bonding in a molecule of nitrogen, N₂
Draw a dot and cross diagram to show the covalent bonding in a molecule of oxygen, O₂
Draw a dot and cross diagram to show the covalent bonding in a molecule of water, H₂O
Explain why carbon dioxide gas, CO₂, is a gas at room temperature
Carbon dioxide has a simple molecular structure with weak intermolecular forces that require little energy to overcome
Explain why methane gas, CH₄, is a gas at room temperature
Methane has a simple molecular structure with weak intermolecular forces that require little energy to overcome
If a substance has a simple molecular structure, what physical state might it be at room temperature?
Gas or liquid (low melting point)
Why is the boiling point of a larger molecule higher than that of a smaller molecule?
Larger molecules have more attractions between them which must be overcome when a substance boils
(Triple only) Draw a diagram to show the bonding in a metal
(Triple only) Describe the bonding in a metal
The strong electrostatic attraction between a regular structure of positive metal ions and a sea of delocalised electrons
(Triple only) Explain why metals are good conductors of electricity
Metals have delocalised electrons which are free to move
(Triple only) Explain why metals are malleable
Metals have layers of ions that can slide over each other
(Triple only) What does the word malleable mean?
able to be hammered or pressed into shape without breaking or cracking
(Triple only) Why do metals have high melting and boiling points?
There is a strong electrostatic attraction between a regular structure of positive metal ions and a sea of delocalised electrons
State 4 observations when sodium reacts with water
1) fizzing occurs 2) sodium moves around 3) sodium melts 4) sodium disappears 5) sodium floats
State 5 observations when potassium reacts with water
1) fizzing occurs 2) potassium moves around 3) potassium melts 4) lilac flame is seen 5) potassium disappears 6) potassium floats
What are the elements in group 1 called?
Alkali metals
Write the chemical equation for the reaction betweem sodium and water
2Na + 2H₂O → 2NaOH + H₂
If pieces of lithium, potassium and sodium were added to water, how could observations of the differences reactions indicate the relative reactivity of those 3 metals?
Lithium would bubble the least vigorously, showing it is least reactive. Potassium would give off a lilac flame, showing it is most reactive.
If pieces of lithium, potassium and sodium were cut and exposed to air, how could observations of the differences reactions indicate the relative reactivity of those 3 metals?
Potassium would oxidise the most quickly, showing it is most reactive. Lithium would oxidise the slowest, showing it is least reactive.
Describe the relative reactivities of the elements in Group 1
The reactivity increases as you go down the group, e.g. Li<Na<K<Rb
(Triple only) Explain, by referring to the electronic configurations, why lithium is less reactive than sodium.
Sodium has the electronic configuration 2,8,1 and lithium has 2,1. The outer electron lost from sodium is further from the nucleus therefore the electron is less attracted by the nucleus. So sodium is more reactive than lithium
What are the elements in group 7 called?
Halogens
What colour and state is bromine at room temperature?
red-brown liquid
What colour and state is iodine at room temperature?
dark grey solid
What is the colour and physical state of chlorine at room temperature?
Green gas
Predict what colour and state is astatine at room temperature
black solid
Predict what colour and state is fluorine at room temperature
yellow gas
Suggest how the reactivity of fluorine compares to chlorine
Fluorine is more reactive than chlorine as it is higher in the group.
Describe how reactivity changes as you descend group 7
decreases
Hydrogen bromide is reacted with chlorine to form bromine. Write a chemical equation.
2HBr + Cl₂ → 2HCl + Br₂
Identify the element that is displaced in this reaction: 2HBr + Cl₂ → 2HCl + Br₂
Bromine
In halogen displacement reactions, electrons are transferred from one atom to another. How are these reactions classified?
REDOX
Name the substance with the brown colour that forms whem chlorine is added to potassium iodide solution
Iodine as it is less reactive than chlorine
State the colour change observed when bromine is added to an aqueous solution of potassium iodide
Colourless to brown
What type of reaction occurs if you put a chlorine with a solution of sodium bromide?
displacement
Why does chlorine react with hydrogen bromide?
Chlorine is more reactive and so displaces the bromine.
(Triple only) Explain why bromine is less reactive than chlorine
Both chlorine and bromine react by their nucleus attracting an electron to fill their outer shell. The outer shell of bromine is further from the nucleus, so the attraction is weaker, making it less reactive.
(Triple only) Explain, by referring to the electronic configurations, why fluorine is more reactive than chlorine
Fluorine has the electronic configuration 2,7 and chlorine has 2,8,7. An extra outer electron is gained more easily by fluorine. This is because the outer shell is closer to the nucleus, so an extra electron is attracted more strongly.
State the names of the gases present in air and their % by volume
nitrogen = 78%. oxygen = 21%. argon = 0.96%. carbon dioxide = 0.04%
Name the compound formed when magnesium reacts with oxygen
magnesium oxide
What observations are made when magnesium burns in air?
Bright white light. White solid left behind.
Write the word and chemical equation for the thermal decompostion of calcium carbonate, CaCO₃
calcium carbonate → calcium oxide + carbon dioxide CaCO₃ → CaO + CO₂
Name the greenhouse gas released from burning hydrocabons
carbon dioxide
Why is carbon dixoxide, CO₂ harmful to the environment?
It is a greenhouse gas and may contribute to global warming
Describe a way in which the rusting of iron could be used to show the approximate percentage of oxygen in air
An excess of wet iron filings in left in a closed system with a known volume of air. After several days the volume of air has fallen as the oxygen is used up. The percentage of oxygen in air is calculates as the change in volume of gas divided by the initial volume (x100%)
Describe how the oxidation of copper can be used to show the approximate percentage of oxygen in air
With gas syringes in a closed system, air is passed back and forward over hot copper until the oxygen is used up. When the volume of gas stops decreasing, the percentage by volume of oxygen in the air is calculated as the change in the volume of gas divided by the initial volume (x100%)
Describe how the reaction of hydrochloric acid and various metals could be used to determine the relative reactivity of those metals
Add the various metals to different test tubes containing the same volume and concentration of acid. The metals which bubble more are more reactive.
An experiment investigates which of metals X and Z is more reactive. The result is X + ZSO₄ → X + ZSO₄. Which metal is more reactive?
Z. There is no reaction.
An experiment investigates which of metals X and Z is more reactive. The result is X + ZSO₄ → XSO₄ + Z. Which metal is more reactive?
X. This is a displacement reaction.
Order these metals from the most reactive to the least: aluminium, calcium, copper, gold, iron, lithium, magnesium, potassium, silver, sodium, zinc
potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper, silver, gold
Describe the conditions under which iron rusts
oxygen and water
Write the word equation for the formation of rust
iron + oxygen + water → hydrated iron (III) oxide
Explain how galvanising prevent rusting
Zinc is more reactive than iron. Zinc reacts with oxygen instead of iron
State the methods of how the rusting of iron may be prevented
grease, oil, paint, plastic and galvanising
What is galvanising?
When zinc is used to coat a less reactive metal to prevent that metal from corrosion
What is sacrificial protection?
Sacrificial protection is when a more reactive metal is connected to a less reactive metal. Only the more reactive metal corrodes, so protecting the less reactive metal
Explain in 2 different ways why rusting is described as an oxidation reaction
iron gains oxygen / iron loses electrons
Identify the species that is oxidised in the following reaction. Explain your answer: 2Br⁻ + Cl₂ → 2Cl⁻ + Br₂
Bromide. Loses electrons
Identify the species that is reduced in the following reaction. Explain your answer: 2Br⁻ + Cl₂ → 2Cl⁻ + Br₂
Chlorine. Gains electrons
If a substance gains oxygen in a reaction how is the process described?
Oxidation
If a substance loses oxygen in a reaction how is the process described?
Reduction
Is the production of iron from iron ore oxidation or reduction?
Reduction
State the meaning of the term oxidising agent
A substance that gives oxygen or removes electrons (it is itself reduced)
State the meaning of the term redox
A reaction involving both reduction and oxidation
State the meaning of the term reducing agent
A substance that takes oxygen or gives electrons (it is itself oxidised)
What is it called when a metal reacts with oxygen in the air to form an oxide layer?
Oxidation
Write the word equation to represent the reaction between hydrochloric acid and calcium
hydrochloric acid + calcium → calcium chloride + hydrogen
Write the word equation to represent the reaction between sulfuric acid and magnesium
sulfuric acid + magnesium → magnesium sulfate + hydrogen
(Triple only) State 2 properties that makes aluminium suitable for manufacturing aircraft
Low density & resists corrosion
(Triple only) Apart from being a mixture of metals, what non-metal is often added to alloys to make them stronger?
Carbon
(Triple only) What is an alloy?
An alloy is a mixture of a metal and one or more elements, usually other metals or carbon
(Triple only) Alloys contain different sized positive ions. What properties does this give alloys compared to pure metals?
Alloys are harder and less malleable than pure metals
State the colour of litmus in acidic and alkaline solutions
acidic = red alkali = blue
State the colour of methyl orange in acidic and alkaline solutions
acidic = red alkali = yellow
State the colour of phenolphthalein in acidic and alkaline solutions
acidic = colourless alkali = pink
What is the universal indicator colour of a pH 0-3 solution?
Red
What is the universal indicator colour of a pH 11-14 solution?
Purple
What is the universal indicator colour of a pH 4-6 solution?
Yellow
What is the universal indicator colour of a pH 7 (neutral) solution?
Green
What is the universal indicator colour of a pH 8-10 solution?
Blue
What is an acid?
An acid is a source of hydrogen ions, H⁺
What is an alkali?
An alkali is a source of hydroxide ions, OH⁻
What is a base?
A substance which can neutralise an acid, forming salt and water only
(Triple only) Describe how to carry out an acid-alkali titration
1) Pipette 25cm³ of alkali into a conical flask. 2) Add indicator. 3) Fill a burette with acid, record the initial volume. 4) Whilst swirling the flask, add the acid dropwise until the indicator changes colour. 5) Record the volume and calculate the volume of acid which was added. 6) Repeat until two concordant results (within 0.2cm³ of each other). 7) Result is the average of all concordant results.
(Triple only) Draw a burette
(Triple only) Draw a pipette
Is aluminium sulfate soluble?
yes
Is barium carbonate soluble?
no
Is barium sulfate soluble?
no
Is silver chloride soluble?
no
Is sodium sulfate soluble?
yes
State the solubility rule for carbonates salts
all carbonates are insoluble, except those of sodium, potassium and ammonium
State the solubility rule for chloride salts
all are soluble, except silver chloride
State the solubility rule for nitrate salts
all nitrates are soluble
State the solubility rule for sodium, potassium and ammonium salts
all common sodium, potassium and ammonium salts are soluble
State the solubility rule for sulfate salts
all sulfates are soluble, except those of barium and calcium
What is defined as a proton acceptor?
An alkali
What is defined as a proton donor?
An acid
An acid is called a proton _________
An acid is a proton donor
An alkali is called a proton _________
An alkali is a proton acceptor
acid + alkali →
acid + alkali → salt + water
acid + base →
acid + base → salt + water
acid + metal →
acid + metal → salt + hydrogen
acid + metal carbonate →
acid + metal carbonate → salt + carbon dioxide + water
Describe the observations of the reaction of calcium carbonate and dilute hydrochloric acid
fizzing and solid disappears
Describe the observations of the reaction of magnesium and dilute sulfuric acid
fizzing and metal disappears
Give the formula of sulfuric acid
H₂SO₄
Give the name of the substance which has formula HNO₃
nitric acid
Give the name of the substance which has the formula HCl (aq)
hydrochloric acid
hydrochloric acid + magnesium →
hydrochloric acid + magnesium → magnesium chloride + hydrogen
hydrochloric acid + sodium hydroxide →
hydrochloric acid + sodium hydroxide → sodium chloride + water
nitric acid + calcium carbonate →
nitric acid + calcium carbonate → calcium nitrate + carbon dioxide + water
sulfuric acid + copper oxide →
sulfuric acid + copper oxide → copper sulfate + water
What is an alkali compared to a base?
Alkalis are bases that are soluble in water
A pure, dry sample of a soluble salt can be prepared starting with an insoluble reactant. What is this method called?
Excess solid method
Describe the method to prepare a pure dry sample of copper sulfate (soluble salt)
1) Heat acid in a beaker. 2) Add base until excess and stir with glass rod. 3) Filter the mixture using filter paper and funnel. 4) Heat the filtered solution (filtrate) until a hot saturated solution forms. 5) Allow the solution to cool so that hydrated crystals form. 6) Remove the crystals by filtration and wash with distilled water. 7) Dry by leaving in a warm place.
(Triple only) A pure, dry sample of a soluble salt can be prepared starting from an acid and alkali. What are the two stages of this method called?
Titration then crystallisation
(Triple only) Describe the method to prepare a pure dry sample of sodium chloride (soluble salt)
1) Pipette 25cm³ of alkali into a conical flask. 2) Do not add indicator. 3) (Using titration values)Titrate the known volume acid into conical flask containing alkali. 4) Transfer to an evaporating basin. 5) Heat the solution until a hot saturated solution forms. 6) Allow the solution to cool so that hydrated crystals form. 7) Remove the crystals by filtration and wash with distilled water. 8) Dry by leaving in a warm place.
(Triple only) A pure, dry sample of an insoluble salt can be prepared starting with two soluble reactants. What is this method called?
Precipitation method
(Triple only) Describe an experiment to prepare a pure, dry sample of an insoluble salt, starting from two soluble reactants
1) Mix the two salt solutions together in a beaker. 2) Stir with glass rod. 3) Filter using filter paper and funnel. 4) Wash with distilled water. 5) Dry by leaving in a warm place.
When preparing hydrated copper(II) sulfate crystals starting from copper(II) oxide, why is an excess of copper (II) oxide added?
To ensure all the acid has reacted so there is no acid left
When preparing hydrated copper(II) sulfate crystals starting from copper(II) oxide, why is the acid gently heated?
To speed up the reaction
(Triple only) What method would be followed to prepare a sample of pure, dry lead (II) sulfate?
Precipitation method
A gas is bubbled through limewater and the limewater goes cloudy. Identify the gas.
Carbon dioxide
Describe the test for ammonia gas
Turns damp red litmus paper blue
Describe the test for carbon dioxide gas
Bubble the gas through limewater and see if it goes cloudy
Describe the test for chlorine gas
Turns moist litmus paper white (bleaches)
Describe the test for hydrogen gas
Use a lit splint to see if the gas pops
Describe the test for oxygen gas
Use a glowing splint and see if it relights
Describe the test for carbon dioxide gas
Bubble the gas through limewater and see if it goes cloudy
Describe the test for hydrogen gas
Use a lit splint to see if the gas pops
Describe how you would carry out a flame test
Put solid onto a wire. Put into a blue flame
In a flame test, why is hydrochloric acid used?
To clean the wire of any unwanted ions
In a flame test, a blue-green colour is seen. Give the formula of the cation which is present.
Cu²⁺
In a flame test, a orange-red colour is seen. Give the formula of the cation which is present.
Ca²⁺
In a flame test, a red colour is seen. Give the formula of the cation which is present.
Li⁺
In a flame test, a lilac colour is seen. Give the formula of the cation which is present.
K⁺
In a flame test, a yellow colour is seen. Give the formula of the cation which is present.
Na⁺
How would you test for the ammonium ion (NH₄⁺)?
Add sodium hydroxide. If ammonium ions were present, ammonia gas will form which will turn damp red litmus paper blue
What is the test for copper (II) ions (Cu²⁺) and what is the result?
Add NaOH. A blue precipitate forms.
What is the test for iron (II) ions (Fe²⁺) and what is the result?
Add NaOH. A green precipitate forms.
What is the test for iron (III) ions (Fe³⁺) and what is the result?
Add NaOH. A brown precipitate forms.
What is the test for NH₄⁺ ions and what is the result?
Add NaOH. The gas (ammonia) turns damp red litmus paper blue.
Describe how you would test for carbonate ions (CO₃²⁻) and what is the result if they are present?
Add nitric acid and see if carbon dioxide bubbles form
Describe how you would test for sulfate ions (SO₄²⁻) and what is the result if they are present?
Add dilute HCl, followed by barium chloride (BaCl₂). A white precipitate will form
Describe the test for bromide ions
Add dilute nitric acid and silver nitrate. A cream precipitate of silver bromide is formed.
When testing a sample for ions, hydrochloric acid and then barium chloride are added to a sample. A white precipitate forms. What is the name of that precipitate?
barium sulfate
When testing for halide ions, after silver nitrate is added to a sample a cream precipitate is formed. Give the formula of the anion present in the sample.
Br⁻
When testing for halide ions, after silver nitrate is added to a sample a white precipitate is formed. Give the formula of the anion present in the sample.
Cl⁻
When testing for halide ions, after silver nitrate is added to a sample a yellow precipitate is formed. Give the formula of the anion present in the sample.
I⁻
When testing for halide or sulfate ions, why is acid added added first?
to remove any carbonate ions
Which two substances are added when testing for halide ions, and what is the result if they are present?
Add dilute nitric acid and silver nitrate
Which two substances are added when testing for the sulfate (SO₄²⁻) ions? (2)
Add dilute HCl, followed by barium chloride (BaCl₂)
Describe the chemical test for water
Add water to anhydrous copper(II) sulfate which will change from white to blue if water is present
Describe a test to show whether water is pure
Heat the sample and measure the temperature. If the sample is pure water it will boil at 100⁰C
What is meant by the term endothermic?
A reaction in which heat energy is taken in (surroundings get colder)
What is meant by the term exothermic?
A reaction in which heat energy is given out (surroundings get hotter)
Explain why experimental values of enthalpy change differ from theoretical values
Heat energy is lost to the surroundings. Not all the reactants are used up.
In a calorimetry experiment to investigate the heat energy released by the combustion of ethanol, why should the water in the calorimeter be stirred?
To ensure the heat energy is mixed evenly throughout all the water
Use Q=mcΔT and c=4.18J/°C/g. 25cm³ of sulfuric acid is put into a boiling tube. The starting temperature is 21°C. A spatula of iron filings is added. After a while the temperature reaches 33°C. What is the total heat energy change?
1254 J
Use Q=mcΔT and c=4.18J/°C/g. A spatula of sodium fluoride is put into a boiling tube with 25cm³ of water. The temperature drops from 22.0°C to 18.6°C. What is the total heat energy change?
-355 J
Use Q=mcΔT and c=4.18J/°C/g. A strip of magnesium is added to a beaker with 200cm³ of copper (II) sulfate. The temperature starts at 21.7°C and rises to a maximum of 23.1°C. What is the total heat energy change?
1170 J
In a combustion calorimetry experiment, 0.78g of ethanol (C₂H₅OH) produced 12,540 J of heat energy. Calculate the molar enthalpy change.
738 kJ/mol
State the units of molar enthalpy change.
kJ/mol
(Triple only) Draw an energy level diagram for an endothermic reaction and use ΔH to represent the enthalpy change
(Triple only) Draw an energy level diagram for an exothermic reaction and use ΔH to represent the enthalpy change
(Triple only) What does the symbol ΔH mean
enthalpy (energy) change
(Triple only) Explain, in terms of making and breaking bonds, why a reaction could be endothermic
The energy need to break the bonds is more than the energy released to make the bonds
(Triple only) Explain, in terms of making and breaking bonds, why a reaction could be exothermic
The energy need to break the bonds is less than the energy released to make the bonds
(Triple only) In an endothermic reaction, which takes more energy: the breaking of bonds or the making of new bonds?
Breaking bonds
(Triple only) In an exothermic reaction, which takes more energy: the breaking of bonds or the making of new bonds?
Making new bonds
(Triple only) Is breaking bonds exothermic or endothemic?
Endothermic
(Triple only) Is making new bonds exothermic or endothemic?
Exothermic
(Triple only) Assuming bond energies in kJ/mol: H-C 412, C-C 348, O-H 463, C-O 360, C=C 612. Calculate the molar enthalpy change for the reaction: ethanol → ethene + water
+45 kJ/mol
(Triple only) In a chemical reaction, 250 kJ/mol is taken to break all the bonds and 280 kJ/mol is released when new bonds are formed. What is the overall molar enthalpy of the reaction?
-30 kJ/mol
(Triple only) In a chemical reaction, the overall molar enthalpy is +87 kJ/mol. Is this reaction exothermic or endothermic?
Endothermic
(Triple only) In a chemical reaction, the overall molar enthalpy is -87 kJ/mol. Is this reaction exothermic or endothermic?
Exothermic
Are combustion reactions exothermic or endothermic?
Exothermic
Are displacement reactions exothermic or endothermic?
Exothermic
Are neutralisation reactions exothermic or endothermic?
Exothermic
When a solid dissolves, is this process exothermic or endothermic?
Endothermic
Calcium carbonate reacts with an excess of hydrochloric acid to produce carbon dioxide. Sketch a graph to show the total volume of gas produced over time. Add a line to show the total volume if half the mass of calcium carbonate is used.
Draw a diagram to explain that a catalyst provides an alternative pathway with lower activation energy.
Mg + 2HCl → MgCl₂ + H₂ Assume acid is in excess. Sketch a graph showing total gas produced over time. Add a second line showing if double the concentration of acid is used.
Mg + 2HCl → MgCl₂ + H₂ Sketch a graph showing total gas produced over time. Add a second line showing if a lower temperature is used
Mg ribbon and an excess of HCl react to product a gas. Sketch a graph showing the total volume of gas over time. Add a second line for using powdered magnesium.
The reaction between magnesium and hydrochloric acid was used to measure the rate of reaction at different temperatures. Name 4 things which should be kept constant.
Temperature of acid. Volume of acid. Concentration of acid. Mass of magnesium. Surface area of magnesium.
On a graph showing gas produced (verticle axis) over time (horizontal axis), how does the line tell us the rate of reaction?
The steeper the line, the faster the rate of reaction
State 5 ways in which the rate of reaction could be increased
Increase surface area (solids), increase temperature, increase concentration (solutions), increase pressure (gases), add an appropriate catalyst
What happens to the rate of reaction if a catalyst is added?
Rate of reaction increases
What happens to the rate of reaction if the concentration of solutions is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the pressure of gases is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the surface area of a solid is INCREASED?
Rate of reaction increases
What happens to the rate of reaction if the temperature is INCREASED?
Rate of reaction increases dramatically
What simple change could be made to a reaction to speed it up dramatically?
Heat it up
What happens to the rate of reaction if the temperature is INCREASED?
Rate of reaction increases dramatically
Explain the effects of increasing the concentration of solutions on the rate of a reaction in terms of particle collision theory
1) more particles in same space 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the pressure of gases on the rate of a reaction in terms of particle collision theory
1) more particles in same space 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the surface area of a solid on the rate of a reaction in terms of particle collision theory
1) more particles exposed 2) more frequent collisions 3) increase rate of reaction
Explain the effects of increasing the temperature on the rate of a reaction in terms of particle collision theory
1) particles have more kinetic energy 2) more frequent collisions 3) and a higher proportion of the collisions which occur have greater or equal to the activitation energy 4) increase rate of reaction
What is a catalyst?
A substance that speeds up a chemical reaction but is chemically unchanged at the end of the reaction
What type of substance speeds up a chemical reaction but is chemically unchanged at the end of the reaction?
Catalyst
Explain how a catalyst works
A catalyst provides an alternative pathway with lower activation energy
(Triple only) What happens if two particles collide with less than the activation energy
No reaction
(Triple only) What is meant by the term activation energy?
The minimum energy that the particles in collision must have if a reaction is going to occur
(Triple only) With how much energy must two particles collide for a reaction to occur?
The particles must collide with an energy greater or equal to the activation energy
Give a simple reaction can be used to investigate the effect of changing concentration on the rate of reaction
Marble chips added to hydrochloric acid of various concentrations
Give a simple reaction can be used to investigate the effect of changing surface area on the rate of reaction
hydrochloric acid added to either marble chips of powdered caclium carbonate
Describe the laboratory preparation of oxygen from hydrogen peroxide
Hydrogen peroxide is added to a flask containing a catalyst of manganese oxide, MnO₂. Oxygen is produced and is collected underwater.
State the catalyst used for making oxygen through the decomposition of hydrogen peroxide
manganese(IV) oxide, MnO₂
What reactant is used to produce a sample of oxygen in the lab?
hydrogen peroxide
Write the chemical equation for the decompostion of hydrogen peroxide, H₂O₂
2H₂0₂ → 2H₂0 + O₂
Write the word equation for the decompostion of hydrogen peroxide, H₂O₂
hydrogen peroxide → water + oxygen
Explain the term hydrocarbon
A hydrocarbon is a molecule containing only hydrogen and carbon
Show the empirical formulae, molecular formulae, general formulae, structural formulae and displayed formulae of ethane
Explain the term functional group
A functional group is an atom or a group of atoms that determine the chemical properties of a compound
Explain the term homologous series
A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties
What are isomers?
Molecules with the same molecular formula but with a different structure
Explain the term homologous series
A homologous series is a family of compounds with 1) the same general formula 2) similar chemical properties 3) trends in their physical properties
Explain the term isomerism
Molecules with the same molecular formula but with a different structure
Draw the displayed formula for 2,3-dimethyl hexane
Write all the possible different structural and displayed formulae of C₄H₁₀
What is a substitution reaction?
A reaction where an atom or group of atoms is replaced by a different atom or group of atoms
What is an addition reaction?
A reaction where an atom or group of atoms is added to a molecule without taking anything away
What is combustion?
Combustion is burning a substance, and is a reaction with oxygen
What is crude oil?
A mixture of hydrocarbons
Explain how crude oil is separated into fractions
Crude oil is separated by fractional distillation. Crude oil is heated and the oil evaporates. It then goes into the tower. As the vapours rise up the tower the temperature falls. Different sized fractions condense at different heights because they have different boiling points. Smaller molecules condense high up the tower. Larger molecules condense low down in the tower. Then the fractions are collected.
What is the name of the process in which crude oil is separated into its various components?
Fractional distillation
Recall a use for each of the 6 fractions obtained from the fractional distillation of crude oil
refinery gases=cooking; gasoline=fuel for cars; kerosene=fuel for planes; diesel=fuel for lorries; fuel oil=fuel for ships; bitumen=surfacing roads
Recall the names of the main fractions obtained from crude oil, in order of lowest boiling point first
Refinery gases, gasoline, kerosene, diesel, fuel oil and bitumen
Describe the trend in boiling points of the main fractions in crude oil
Boiling point increases as the number of carbon atoms (chain length) increase
In the fractional distillation of crude oil, how does boiling point change as the chains get longer?
Increases
What does volatile mean? Which fraction of crude oil is the most volatile?
If a substance is volatile it evaporates easily. Refinery gas is the most volatile fraction of crude oil.
What is meant by the term viscosity?
The viscosity of a fluid describes how easily it flows. Water has a low viscosity, it flows very easily. Crude oil has a higher viscosity than water, it does not flow very easily.
What is a fuel?
A fuel is a substance that, when burned, releases heat energy
Recall the products of the complete combustion of alkanes
Carbon dioxide and water
Recall the products of the incomplete combustion of alkanes
Carbon, carbon monoxide, carbon dioxide and water
Write a chemical equation for the complete combustion of propane
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
Explain why carbon monoxide is dangerous to humans
It is poisonous because it reduces the capacity of the blood to carry oxygen
Why does incomplete combustion occur?
When there is an insufficient supply of oxygen for complete combustion
In car engines, sparks cause the formation of some gases which contribute to acid rain. What are these gases?
Oxides of nitrogen
What is produced when nitrogen reacts with oxygen?
Nitrogen oxides
Why can nitrogen react with oxygen in a car engine?
The temperature is very high
How does sulfur dioxide form in car engines?
Petrol includes the impurity sulfur, and when the petrol combusts some sulfur dioxide is formed
Describe how nitrogen oxides and sulfur dioxide contribute to acid rain
Nitrogen oxides created in hot car engines and sulfur dioxide released when fossil fuels are burned combine with water in the atmosphere to form acidic solutions
Describe the problems caused by acid rain
Acid rain damages plant life and life in lakes. It also corrodes limestone and some metals.
State the problem associated with sulfur dioxide in the atomosphere?
The sulfur dioxide combines with water in the atmosphere to form acidic solutions (acid rain)
Write the chemical equation for sulfur dioxide dissolving in water to form acid rain
SO₂ + H₂O → H₂SO₃
State the conditions for the cracking of hydrocarbons
Aluminium oxide catalyst heated to 600°C
What is cracking?
The breaking down of long-chain alkanes into alkenes and shorter-chain alkanes
When long chain alkanes are cracked, what is produced?
Shorter chain alkanes and alkenes
Write a chemical equation for the cracking of decane
C₁₀H₂₂ → C₂H₄ + C₈H₁₈
Crude oil contains a surplus of long chain alkanes and there is much higher demand for shorter chain alkanes. What process is used to deal with this imbalance?
Cracking
Explain why cracking is an important process in the oil industry
Cracking converts long chain hydrocarbons into short chain hydrocarbons. Crude oil contains a surplus long chains. Shorter chain hydrocarbons are in greater demand, e.g. petrol. Cracking also produces alkenes which are used in making polymers and ethanol.
State the general formula of alkanes
CnH2n+2
State the names and molecular formulae of the first 5 alkanes
methane (CH₄), ethane (C₂H₆), propane (C₃H₈), butane (C₄H₁₀), pentane (C₅H₁₂)
Explain the term saturated
A molecule containing only single bonds
Draw the displayed formulae for ethane
Draw the displayed formulae for propane
What is the molecular formula for butane?
C₄H₁₀
What is the molecular formula for methane?
CH₄
State the conditions for the reaction of methane with bromine to form bromomethane
UV light
What are the two products of the reaction between methane and bromine? (2)
Bromomethane (CH₃Br) and hydrogen bromide (HBr)
What else is needed for methane to react with bromine?
UV light
What is the name given to the type of reaction that occurs when ethane reacts with bromine under UV light
Substitution
Would methane normally react with bromine?
No (because it is saturated)
Write the chemical equation for the reaction between methane and bromine
CH₄ + Br₂ → CH₃Br +HBr
Write the word equation for the reaction between methane and bromine
methane + bromine → bromomethane + hydrogen bromide
Of which homologous series is >C=C< (a carbon-to-carbon double bond) the functional group?
Alkenes
What is the functional group of an alkene?
>C=C< (a carbon-to-carbon double bond)
State the general formula for alkenes
CnH2n
Explain the term unsaturated
A molecule containing a carbon-carbon double bond
Why are alkenes classified as unsaturated hydrocarbons?
They contain a double bond
Draw the displayed formulae for butene
Draw the displayed formulae for ethene
Draw the displayed formulae for the two straight chain isomers of butene. Name these two isomers
State the names and molecular formulae of the first 3 alkenes
ethene (C₂H₄), propene (C₃H₆), butene (C₄H₈)
State the colour change in the reaction of an alkene with bromine water
Orange to colourless
State the colour change when an alkane is mixed with bromine water
No change
What is produced when an alkene reacts with bromine?
A dibromoalkane
What two things can be added together to produce a dibromoalkane?
An alkene and bromine
What type of reaction takes place when bromine reacts with an alkene?
Addition
Bromine is added to a sample of an alkane and also to a sample of an alkene. Describe the result of each.
With the alkane, no change (stays brown). With the alkene, changes from brown to colourless
Describe, in terms of structure and bonding, what happens when ethene molecules are converted into poly(ethene)
One bond in the double bond breaks. Monomers join together to form a long chain. Polymer contains only single bonds
Explain what is a monomer
Monomers are the many small molecules (such as ethene) which add together to make a polymer
Explain what is an addition polymer
An addition polymer is large molecule made by adding many small molecules (each containing a double bond) to form one much larger molecule
What is the process of joining monomers together called?
Polymerisation
Draw the equation to show the formation of poly(ethene)
Draw the equation to show the formation of poly(propene)
Draw the repeating unit for poly(but-2-ene)
Draw the repeating unit for poly(chloroethene)
Draw the repeating unit for poly(ethene)
Draw the displayed formula of the monomer used to make poly(but-1-ene)
Draw the displayed formula of the monomer used to make poly(propene)
Explain why addition polymers are hard to dispose of
They are inert as they have strong C-C bonds. This makes them non-biodegradeable.
What is meant by the term biodegradable?
The break down of a substance by microorganisms