Volumes of gases

This question is about Group 1 metals.

A teacher adds a small piece of lithium metal to a trough containing water.

Complete the equation for the reaction between lithium and water by adding the state symbols.

Give two observations made when the lithium is added to the water.

The reaction produces 375 cm³ of hydrogen gas at room temperature and pressure (rtp).

Show, by calculation, that the mass of lithium added is between 0.20 g and 0.30 g.

[1 mol of gas has a volume of 24 000 cm³ at rtp]

[for lithium, A_r = 7]

Potassium is more reactive than lithium.

The diagram shows the electronic structure of an atom of lithium and an atom of potassium.

Give one observation that is different when a small piece of potassium, instead of lithium, is added to water.

Explain why potassium is more reactive than lithium.

Refer to the electronic structure of lithium and of potassium in your answer.

A teacher adds a small piece of lithium to water and collects the gas produced.

Give two observations when lithium is added to water.

The teacher adds a few drops of universal indicator to the solution at the end of the reaction.

Explain the final colour of the universal indicator.

This is the equation for the reaction between lithium and water.

The teacher collects 550 cm³ of hydrogen at rtp.

Calculate the mass, in grams, of lithium that the teacher added to the water.

[one mole of gas at rtp has a volume of 24 000 cm³]

[for lithium, A_r = 7]

[for carbon A_r = 12 for hydrogen, A_r = 1 for oxygen A_r = 16]

The teacher then adds a small piece of potassium to water.

Give one observation seen with potassium that is not seen with lithium.

Explain why potassium is more reactive than lithium.

Refer to atomic structure in your answer.

This question is about electrolysis.

This apparatus is used to collect the gases produced when an electric current passes through dilute sulfuric acid.

inert electrode inert electrode

Name a suitable material for the inert electrodes.

Give a test to show that the gas produced at the positive electrode is oxygen.

Give a test to show that the gas produced at the negative electrode is hydrogen.

Give an ionic half-equation for the formation of hydrogen at the negative electrode.

The oxygen gas in the tube has a volume of 17.8 cm³ at rtp.

Calculate the mass, in grams, of oxygen gas in the tube.

Give your answer to 3 significant figures.

[for O₂ at rtp, molar volume = 24 000 cm³]

This apparatus is used to electrolyse a concentrated solution of sodium chloride.

Give a reason why sodium chloride solution conducts electricity.

The positive ions in the solution are H⁺ and Na⁺.

Give a reason why hydrogen forms at the negative electrode rather than sodium.

A sample of the solution is taken from near the negative electrode. The sample is tested with universal indicator.

Explain the final colour of the universal indicator.

The diagram shows two pieces of apparatus used in a titration.

Give the names of these pieces of apparatus.

Give the name of a suitable indicator that can be used in an acid-alkali titration.

A student does a titration using sodium carbonate solution and dilute nitric acid.

This is the equation for the reaction.

The table shows the concentrations of the two solutions and the volume of sodium carbonate used in the titration.

Use the equation and the data in the table to answer these questions.

Calculate the volume of dilute nitric acid that the student would need to neutralise the sodium carbonate solution.

Calculate the volume, in cm³, of carbon dioxide gas at rtp that would be produced from the 25.0 cm³ of the sodium carbonate solution.

[at rtp, molar volume = 24 000 cm³]

Describe a test to show that sodium carbonate solution contains carbonate ions.

Describe the forces of attraction in metallic bonding.

When a small piece of potassium is added to water, bubbles of hydrogen gas are observed.

Give the test for hydrogen gas.

Give two other observations that would be made.

Explain why lithium is less reactive than potassium.

Refer to atomic structure in your answer.

This is the equation for the reaction between sodium and water.

A mass of 0.750 g of sodium is reacted with an excess of water.

Calculate the volume of hydrogen gas produced, in cm³, at room temperature.

[molar volume of hydrogen at rtp = 24 000 cm³]

[for Na,A_r = 23]

Give your answer to three significant figures.

This is the equation for the reaction between sodium hydroxide and sulfuric acid.

A volume of 25.0 cm³ of sodium hydroxide solution is completely neutralised by 16.3 cm³ of 0.0500 mol / dm³ sulfuric acid.

Calculate the concentration of the sodium hydroxide solution in mol / dm³.

concentration =_........ mol / dm

Methane reacts with steam to form carbon monoxide and hydrogen.

This is the equation for the reaction.

State why carbon monoxide is poisonous to humans.

Explain the effect, if any, on the yield of hydrogen at equilibrium when a nickel catalyst is used.

The reaction conditions for this reaction are a temperature of 700 °C and a pressure of 5 atmospheres.

The temperature of the reaction mixture is reduced to 600 °C, but the pressure is kept at 5 atmospheres.

Explain the effect on the yield of hydrogen at equilibrium.

The pressure of the reaction mixture is reduced to 4 atmospheres, but the temperature is kept at 700 °C.

Explain the effect on the yield of hydrogen at equilibrium.

Calculate the volume, in dm³, of methane gas at rtp needed to produce 6.6 tonnes of hydrogen gas.

[at rtp, molar volume = 24 dm³ 1 tonne = 10⁶g]

Give your answer in standard form.

When 10.0 kg of a solid fuel is burned, the heat energy produced is 3.28 × 10⁵kJ.

Calculate the heat energy, in kJ/mol, produced by the fuel.

You should assume that the fuel is pure carbon.

Give your answer to three significant figures.

[for carbon, A_r = 12]

heat energy =_........ kJ/mol

The fuel actually contains some impurities, including sulfur.

There is 600 g of sulfur in 20 kg of fuel.

Calculate the percentage of sulfur in the fuel.

When the fuel burns, the 600 g of sulfur produces sulfur dioxide gas.

Calculate the volume, in cm³, of sulfur dioxide gas that would be produced at room temperature and pressure (rtp) when the fuel burns.

[for a gas, molar volume = 24 dm³ at rtp]

State the name of the environmental problem caused by sulfur dioxide in the atmosphere.

This question is about hydrazine, N₂H₄

This is the displayed formula for a molecule of hydrazine.

Complete the dot‑and‑cross diagram for hydrazine.

Use the data in the table to calculate the total energy needed to break all the bonds in the reactants.

Use the data in the table to calculate the total energy released when all the bonds in the products are made.

Calculate the enthalpy change, Δ H, in kJ/mol, for the reaction.

ΔH =_........ kJ/mol

Explain, in terms of bonds broken and bonds made, why this reaction is exothermic.

A sample of hydrazine is completely decomposed.

This is the equation for the decomposition of hydrazine.

The products of the decomposition are bubbled through 1100 cm³ of water.

The ammonia completely dissolves in the water, but nitrogen is insoluble in water.

The nitrogen has a volume of 1570 cm³ at room temperature and pressure (rtp).

Calculate the concentration, in mol/dm³, of the ammonia solution.

Give your answer to 3 significant figures.

[for a gas at rtp, molar volume = 24 000 cm³]

concentration =_........ mol/dm

Titanium is an important metal in industry.

Titanium dioxide (TiO₂) can be converted into titanium metal in two stages.

Stage 1 titanium dioxide is converted into titanium(IV) chloride (TiCl₄)

Stage 2 titanium(IV) chloride is converted into titanium

This is the equation for the reaction in stage 1.

Calculate the volume, in dm³, of chlorine gas at rtp needed to react completely with 20 tonnes of titanium dioxide.

Give your answer in standard form.

[1 tonne = 10⁶g M_r of TiO₂ = 80]

[molar volume of chlorine gas at rtp = 24 dm³]

In stage 2, titanium(IV) chloride vapour is passed through molten magnesium in a container filled with argon.

This is the equation for the reaction in stage 2.

Explain why the container is filled with argon rather than air.

Aeroplanes are made of an alloy containing aluminium and titanium.

Explain why the alloy is stronger than pure titanium metal.

You may include diagrams in your answer.

In the presence of an iron catalyst, nitrogen reacts with hydrogen to form ammonia.

The reaction conditions used are a temperature of 450C and a pressure of 200 atmospheres.

This is the equation for the reaction.

State what the symbol represents.

Give the reason for using a catalyst.

The reaction mixture is kept at a pressure of 200 atmospheres, but the

Explain the effect of this change on the yield of ammonia at equilibrium.

The reaction mixture is kept at a temperature of 450C, but the pressure is increased to 300 atmospheres.

Explain the effect of this change on the yield of ammonia at equilibrium.

Draw an energy level diagram for the reaction between nitrogen and hydrogen.

Include the reactants, products and Δ H in your diagram.

QUESTION 7 CONTINUES ON NEXT PAGE

At the start of the reaction, 48 dm³ of nitrogen is added to 120 dm³ of hydrogen at rtp.

[molar volume of any gas at rtp = 24 dm³]

Show by calculation that the nitrogen is in excess.

The yield of ammonia at equilibrium is 20 %.

Calculate the volume, in dm³, of ammonia formed from 120 dm³ of hydrogen.

This question is about the reactions of Group 1 metals with water.

A teacher adds a piece of sodium to some water containing universal indicator.

The equation for this reaction is

The sodium floats on the surface of the water and the universal indicator changes colour because an alkaline solution is formed.

Give two other observations.

Give the final colour of the universal indicator.

The diagram represents an atom of lithium and an atom of sodium.

Give a reason why lithium and sodium have similar reactions with water.

Explain why lithium is less reactive than sodium.

The teacher adds 0.150 g of lithium to an excess of water and collects the hydrogen gas produced.

The equation for the reaction is

The teacher collects 254 cm³ of hydrogen gas at room temperature and pressure (rtp).

Show by calculation that 1 mol of hydrogen gas has a volume of approximately 24 000 cm³ at rtp.

This question is about three stages in the manufacture of sulfuric acid.

In stage 1, sulfur is burned in oxygen to form sulfur dioxide gas.

State one environmental problem caused by the release of sulfur dioxide into the atmosphere.

A mass of 6.4 tonnes of sulfur is burned to produce sulfur dioxide gas.

Calculate the maximum volume, in dm³, of sulfur dioxide gas that can be produced at rtp.

[molar volume of sulfur dioxide gas at rtp = 24 dm³]

[1 tonne = 10⁶g]

Give your answer in standard form.

In stage 2, sulfur dioxide is reacted with oxygen to form sulfur trioxide gas.

The yield of sulfur trioxide is approximately 98%.

A catalyst is used in this reaction.

Explain how a catalyst increases the rate of a reaction.

The temperature is kept constant.

Give a reason why increasing the pressure would increase the yield of sulfur trioxide.

Suggest why it is not necessary to increase the pressure in stage 2.

In stage 3, the sulfur trioxide is reacted with concentrated sulfuric acid to form a liquid called oleum, H₂S₂O₇

The oleum is then added to water to form concentrated sulfuric acid.

Complete the chemical equations for these two reactions.

Sulfuric acid reacts with ammonia to form ammonium sulfate, (NH₄)₂SO₄

Calculate the percentage by mass of nitrogen in ammonium sulfate.

[M_r of (NH₄)₂SO₄ = 132]

This question is about alcohols, carboxylic acids and esters.

Ethanol can be manufactured by reacting ethene with steam in the presence of a phosphoric acid catalyst.

Which row gives the correct conditions of temperature and pressure for this reaction?

Give the displayed formula of butanol.

Ethanoic acid (CH₃COOH) is a carboxylic acid present in vinegar.

The concentration of CH₃COOH in vinegar can be found by titration with aqueous potassium hydroxide (KOH).

The equation for the reaction is

CH₃COOH + KOH CH₃COOK + H₂O

In a titration, a 25.0 cm³ sample of vinegar is neutralised by 45.00 cm³ of KOH solution of concentration 0.400 mol/dm³.

Calculate the concentration, in mol/dm³, of CH₃COOH in this sample of vinegar.

concentration =_........ mol/dm

A sample of vinegar containing 0.0030 mol of CH₃COOH is poured into a flask.

Calculate the maximum volume, in cm³, of carbon dioxide gas formed at rtp when excess sodium carbonate is added to the flask.

The equation for the reaction is

[Assume that the molar volume of carbon dioxide at rtp is 24 000 cm³]

Alcohols react with carboxylic acids to form esters.

Which alcohol could react to form the ester ethyl propanoate?

Polyesters are formed in condensation polymerisation reactions between dicarboxylic acids and diols.

State one difference between condensation polymerisation and addition polymerisation.

The repeat unit of a polyester is

O O H H

H H

Give the displayed formula of each of the two monomers needed to form this polyester.

Give one advantage of biopolyesters.

A sample of a gaseous hydrocarbon, X, has a volume of 600 cm³ at room temperature and pressure (rtp).

Calculate the amount, in moles, of hydrocarbon X in the sample.

[molar volume of a gas = 24 000 cm³ at rtp]

The mass of the sample of hydrocarbon X is 1.45 g.

Show that the relative molecular mass (M_r) of X is 58

Hydrocarbon X is an alkane.

Show that the molecular formula of X is C₄H₁₀

Give the displayed formula of the branched‑chain isomer of hydrocarbon X.

This question is about octane (C₈H₁₈) which is produced in the gasoline fraction during fractional distillation of crude oil.

The diagram shows a fractionating column.

Describe how crude oil is separated into fractions in the fractionating column.

Octane can also be produced by the process of cracking.

Give the conditions for cracking.

A car is driven at constant speed for 4.00 km.

The exhaust gases are collected and their volume at room temperature and pressure (rtp) is 5.02 × 10⁵cm³.

The exhaust gases include carbon dioxide and oxides of nitrogen.

The carbon dioxide is removed from the exhaust gases. The volume of the remaining gases at rtp is 2.96 × 10⁵cm³.

Explain how oxides of nitrogen form in a car engine.

Give a reason why oxides of nitrogen should not be released into the atmosphere.

Show that the car produces less than 100 g of carbon dioxide per km.

[molar volume of carbon dioxide at rtp = 24 000 cm³]

This question is about reactions involving gases.

Potassium carbonate reacts with dilute hydrochloric acid to produce carbon dioxide gas.

The equation for the reaction is

Calculate the volume, in cm³, of carbon dioxide gas produced when 6.9 g of potassium carbonate reacts with excess dilute hydrochloric acid.

[M_r of K₂CO₃ = 138]

[molar volume of CO₂ at rtp = 24 dm³]

This reaction involving gases is in dynamic equilibrium at a temperature of 225C.

Predict the effect on the yield of CO(g) at equilibrium when the temperature is increased without changing the pressure.

Give a reason for your answer.

Predict the effect on the yield of CO(g) at equilibrium when the pressure is increased without changing the temperature.

Give a reason for your answer.

Ethanol, C₂H₅OH, can be oxidised to produce ethanoic acid, CH₃COOH, by heating it with potassium dichromate(VI).

Name one other reactant needed for this reaction to occur.

Which colour change occurs during this reaction?

When ethanol is burned in air, complete combustion can occur.

The equation for this reaction is

This equation can also be written using displayed formulae to show all the covalent bonds in the molecules.

H H

H H

The table gives the bond energies for these bonds.

Use values from the table to calculate the energy needed to break all the bonds in the reactants.

energy needed_........

Use values from the table to calculate the energy released when all the bonds in the products are formed.

energy released_........

Calculate the molar enthalpy change (Δ H) in kJ/mol, for the complete combustion of ethanol.

Include a sign in your answer.

ΔH =_........ kJ/mol

Ethanol reacts with methanoic acid, HCOOH, in the presence of an acid catalyst to form an ester.

The equation for the reaction is

Give the name of the ester that forms.

Draw the displayed formula for this ester.

When this reaction takes place in a sealed container, the reaction can reach dynamic equilibrium.

Give two characteristics of a reaction at dynamic equilibrium.

Methanoic acid reacts with sodium carbonate to form sodium methanoate, carbon dioxide and water.

The equation for the reaction is

Calculate the volume, in cm³, of carbon dioxide gas produced when 2.3 g of methanoic acid reacts completely with sodium carbonate.

[M_r of HCOOH = 46]

[molar volume of carbon dioxide at rtp = 24 dm³]

This question is about Group 1 metals and their reactions.

When lithium is added to water, bubbles of hydrogen gas are observed.

Give two other observations that could be made.

Give the test for hydrogen gas.

Give one observation that would be different if potassium is used instead of lithium.

The diagram represents an atom of lithium and an atom of potassium.

Explain why potassium is more reactive than lithium.

The equation for the reaction between lithium and water is

A mass of 0.500 g of lithium reacts with an excess of water.

Calculate the volume, in cm³, of hydrogen gas produced at rtp.

[molar volume of a gas at rtp = 24 000 cm³]

Give your answer to three significant figures.

In a reaction between lithium and water, 150 cm³ of lithium hydroxide solution is formed.

The lithium hydroxide solution is then completely neutralised by 24.85 cm³ of 0.100 mol/dm³ sulfuric acid.

The equation for the neutralisation is

Calculate the concentration, in mol/dm³, of the lithium hydroxide solution.

concentration =_........ mol/dm

This question is about some Group 2 elements and their compounds.

Calcium reacts with water to produce calcium hydroxide and hydrogen gas.

Give the word equation for this reaction.

State two observations that would be made during this reaction.

Describe how a pure, dry sample of the insoluble salt, barium sulfate, could be made from the two solids sodium sulfate and barium chloride.

Give an ionic equation for the reaction that occurs.

Include state symbols in your equation.

When magnesium nitrate is heated, magnesium oxide, nitrogen dioxide and oxygen form.

The equation for the reaction is

What is the name for this type of reaction?

Calculate the total volume, in dm³, of gas produced at rtp when 7.7 g of magnesium nitrate completely reacts.

[Assume that the molar volume of a gas at rtp is 24 dm³]

[M_r of Mg(NO₃)₂ = 148]

Give your answer to two significant figures.

Hydrogen gas can be produced by reacting a mixture of methane and steam in the presence of a nickel catalyst.

The reaction conditions are a temperature of 700C and a pressure of 5 atmospheres.

The equation for the reaction is

What does the symbol represent?

The mixture of methane and steam is heated to a temperature greater than 700 °C but the pressure is kept at 5 atmospheres.

Predict the effect of this change on the yield of hydrogen at equilibrium, giving a reason for your answer.

The mixture of methane and steam is kept at the same temperature of 700 °C but the pressure is increased to more than 5 atmospheres.

Predict the effect of this change on the yield of hydrogen at equilibrium, giving a reason for your answer.

Calculate the volume, in dm³, of hydrogen gas at rtp that is produced when 10 tonnes of methane gas completely react with steam.

[molar volume of hydrogen at rtp is 24 dm³]

Give your answer in standard form.

The concentration of NaC l O(aq) in a solution of bleach is found by reacting it with hydrochloric acid.

The equation for the reaction is

An excess of dilute hydrochloric acid is added to 4.00 cm³ of bleach solution.

60.0 cm³ of chlorine gas is produced.

Explain a safety precaution that should be taken when doing this experiment.

Calculate the amount, in moles, of chlorine gas produced. Assume one mole of chlorine gas occupies 24 000 cm³.

Determine the amount, in moles, of NaClO in 4.00 cm³ of bleach.

Calculate the concentration, in mol/dm³, of the bleach solution.

concentration =_........ mol/dm³