11 questions · 110 marks · ≈ 2 hours
This question is about states of matter.
Use the words solid, liquid or gas to give the initial and final state of matter for each of the changes listed in the table. The first one has been done for you. Change Initial state Final state melting solid liquid sublimation condensing evaporation
Particles in a solid are closely packed, arranged in a regular pattern and vibrate about fixed positions. Describe the arrangement and movement of the particles in a gas.
The table gives the melting and boiling points of four pure substances, W, X, Y and Z. Melting point in °C Boiling point in °C W –7 60 X 660 2500 Y 180 1330 Z 115 445 Use data from the table to answer the questions.
Which substance is a gas at 100 °C?
Choose your answer
W
X
Y
Z
Which substance is a liquid for the largest range of temperature?
Choose your answer
W
X
Y
Z
Which substance is a liquid at 1000 °C and a gas at 2000 °C?
Choose your answer
W
X
Y
Z
Substance Y does not conduct electricity when solid but does conduct electricity when molten. Give the type of bonding in substance Y.
Suggest how the melting point of a pure substance changes when an impurity is added.
Lead nitrate and potassium iodide react to form the insoluble solid lead iodide. Crystals of lead nitrate and potassium iodide are placed at opposite ends of a container of water. Solid lead iodide forms after several minutes. The diagram shows the container at the start and after several minutes
Name the two processes that occur before the solid lead iodide forms. 1 2
Explain why solid lead iodide takes less time to form when the reaction is repeated using water at a higher temperature.
The formula for lead nitrate is Pb(NO₃)₂
Give the number of different elements in lead nitrate.
Give the charge on the lead ion in Pb(NO₃)₂
Complete the chemical equation for the reaction between lead nitrate and potassium iodide. Pb(NO₃)₂(aq) + KI(aq) → PbI₂(s) + KNO₃(aq)
This question is about rusting.
When iron rusts, it reacts with oxygen in the air. A student uses the rusting of iron to find the percentage of oxygen in a sample of air. The diagram shows the apparatus. 100 80 60 40 20 0 cm³ air gas syringe wet iron conical flask filings These are the student’s results. volume of air in conical flask and connecting tube = 265 cm³ volume of air in gas syringe at start = 100 cm³ volume of air in gas syringe at end = 25 cm³ Calculate the percentage of oxygen in the sample of air using the student’s results. percentage of oxygen = %
Cars are painted to prevent the iron in car bodies from rusting. Explain how painting prevents the iron in car bodies from rusting.
Some car manufacturers use paint containing tiny particles of zinc. Explain how particles of zinc prevent iron in car bodies from rusting even when this paint is scratched.
This question is about the separation of mixtures.
The box gives some methods used to separate mixtures. crystallisation filtration fractional distillation simple distillation Complete the table by giving the correct method from the box for each separation. Each method can be used once, more than once or not at all. Separation Method insoluble solid from a liquid pure water from a solution liquid from a mixture of liquids with different boiling points soluble solid from a solution
A student uses chromatography to analyse the composition of purple ink. The diagram shows the student’s chromatogram at the end of the experiment. solvent front start line purple A B C D ink
Explain which dyes are contained in the purple ink.
Explain which dye is least soluble in the solvent.
A different chromatography experiment is set up. A spot of food colouring is placed on the start line. A food dye in the colouring has an Rf value of 0.72 The distance between the start line and the solvent front is 120 mm. Calculate the distance the food dye moves from the start line. distance = mm
This question is about salts.
When solutions of salts are mixed together, precipitates sometimes form. The insoluble salt barium carbonate forms as a precipitate when solutions of the soluble salts ammonium carbonate and barium chloride react together. When solutions of the soluble salts potassium chloride and magnesium sulfate are mixed, no precipitate forms. Complete the table to show the results of mixing solutions of some soluble salts. ammonium carbonate solution magnesium sulfate solution barium chloride precipitate of solution barium carbonate potassium chloride no precipitate solution calcium chloride precipitate of solution calcium sulfate
A student has four unlabelled beakers, each containing a colourless solution of a different salt. The four solutions are • potassium carbonate • potassium chloride • potassium iodide • sodium chloride Describe a method to identify each solution. Do not refer to safety in your answer.
This question is about lithium oxide.
The diagram shows the electron configurations of an atom of lithium and an atom of oxygen. lithium oxygen Describe the changes in electronic configuration when lithium and oxygen react to form lithium oxide, Li₂O
Lithium oxide reacts with water to form lithium hydroxide as the only product. A scientist uses this apparatus to measure the temperature change of the reaction. beaker 100 g water polystyrene cup This is the scientist’s method.
Complete the table, giving all values to the nearest 0.1 °C. temperature in °C after adding the lithium oxide temperature in °C before adding the lithium oxide 17.3 temperature rise in °C
Calculate the heat energy change in the reaction. Give your answer to two significant figures. [c = 4.2 J / g / °C] heat energy change = J
In another experiment the scientist obtains these results. amount of lithium oxide in mol 0.0580 heat energy change in J 5210 Calculate the molar enthalpy change (ΔH ) in kJ / mol. Include a sign in your answer. ΔH = kJ / mol
Give a reason why the scientist does the experiment in a polystyrene cup.
This question is about the halogens.
The table gives some information about the halogens. Complete the table by predicting the physical state of astatine at room temperature and the colour of astatine. Physical state at room Halogen Colour temperature fluorine gas yellow chlorine gas pale green bromine liquid red-brown iodine solid grey astatine
Bromine has two isotopes with mass numbers 79 and 81
The relative percentages of each isotope in a sample of bromine are bromine-79 = 51.0% bromine-81 = 49.0% Calculate the relative atomic mass of this sample of bromine. Give your answer to one decimal place. relative atomic mass =
Give a reason why both isotopes of bromine have the same chemical properties.
A student investigates the reactivity of some halogens. She uses these solutions of halogens and their halides.
Explain how these results show the order of reactivity of bromine, chlorine and iodine.
Suggest why the student does not need to add bromine solution to sodium bromide solution.
The ionic equation for the reaction between bromine and sodium iodide is Br₂(aq) + 2I⁻(aq) → I₂(aq) + 2Br⁻(aq) Explain why this is a redox reaction.
Propane is a hydrocarbon with the formula C₃H₈
State why propane is a hydrocarbon.
Name the poisonous gas that forms when propane is burned in a limited supply of air.
State why this gas is poisonous to humans.
The diagram represents a molecule of propane. H H H H C C C H H H H Describe the forces of attraction between the atoms in a molecule of propane.
Propane can be produced by cracking. An equation for cracking is C₁₃H₂₈ → C₃H₈ + 2C₃H₆ + 2C₂H₄ Explain why cracking is an important process in the oil industry.
Propane reacts with bromine in the presence of ultraviolet radiation.
Complete the equation for this reaction. C₃H₈ + Br₂ → +
Give the name of this type of reaction.
This question is about alkanes.
The graph shows the boiling points of several unbranched alkanes. 160 140 120 100 Boiling point in °C 4 5 6 7 8 9 Number of carbon atoms in molecule
Draw a curve of best fit.
Use the graph to find the boiling point of the alkane with 7 carbon atoms in its molecule. Show on the graph how you obtain your answer. boiling point = °C
Explain the trend shown by the graph.
The diagram represents two isomers with the formula C₅H₁₂ H H H H H H H H H H C C C C C H H C C C C H H H H H H H H H H C H H Explain why these compounds are isomers.
An alkane contains 82.8% carbon and 17.2% hydrogen by mass. Show by calculation that the empirical formula of this alkane is C₂H₅
Deduce the molecular formula of this alkane.
The equation for the complete combustion of one mole of an alkane can be represented by alkane + ZO₂ → XCO₂ + YH2O Complete combustion of one mole of the alkane produces 308 g of carbon dioxide and 144 g of water. X, Y and Z are the numbers used to balance the equation. Calculate the values of X, Y and Z. [Mr of CO₂ = 44, Mr of H₂O = 18] X = Y = Z =
This question is about reactions that form gases.
Hydrogen peroxide decomposes to form water and oxygen. The equation for the reaction is 2H₂O₂ → 2H₂O + O₂ 25.0 cm³ of hydrogen peroxide solution are poured into a conical flask and 1.00 g of solid manganese(IV) oxide is added. Bubbles of oxygen gas are formed.
Give the test for oxygen gas.
Describe a method to show that solid manganese(IV) oxide is a catalyst in this reaction and not a reactant.
A student uses this apparatus to investigate the rate of the reaction between zinc and an excess of dilute hydrochloric acid. dilute hydrochloric acid zinc This is the student’s method.
Calculate the mean (average) rate of reaction, in cm³ / s, in the first 120 s. mean rate = cm³ / s
The equation for the reaction between zinc and hydrochloric acid is Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g) Use this equation and the particle collision theory to explain why the rate of reaction is greatest at the start of the reaction.
The student repeats the experiment at a higher temperature but keeps all other conditions the same. On the grid, draw the curve you would expect to see in this experiment.
Explain why the rate of reaction is greater if the same mass of zinc powder is used instead of zinc lumps. All other conditions are kept the same.
In another experiment, the student adds 0.55 g of zinc to a solution containing 2.50 × 10⁻² moles of hydrochloric acid. Use the equation to show that hydrochloric acid is in excess. Zn(s) + 2HCl(aq) → ZnCl₂(aq) + H₂(g) [Ar of Zn = 65]