231 terms

iGCSE Chemistry: Y9 End of Year - core

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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
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
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?
FeBr₃
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
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
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
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
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
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 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)
What happens to the rate of reaction if the temperature is INCREASED?
Rate of reaction increases dramatically
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 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 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 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