185 terms

iGCSE Chemistry: Y10 Michaelmas exam

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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
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
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.
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
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
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
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
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
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⁺
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
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
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
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
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
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 chemical test for water
Add water to anhydrous copper(II) sulfate which will change from white to blue if water is present
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
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 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
Write all the possible different structural and displayed formulae of C₄H₁₀
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