Volumes of gases

Hydrogen can be produced by the reaction of methane with steam.

Methane reacts with steam in the presence of a nickel catalyst to produce hydrogen and a dynamic equilibrium is reached.

The equation for this equilibrium reaction is

methane

The forward reaction takes in heat energy and is endothermic.

Describe the effect of the catalyst on the rate of attainment of equilibrium and on the equilibrium yield of products.

*(ii) A manufacturer produces hydrogen by the reaction of methane with steam in the presence of a nickel catalyst using the conditions

pressure 20 atmospheres

Explain what effect there would be on the rate of attainment of equilibrium and the equilibrium yield of hydrogen if the manufacturer were to use a higher temperature of 1000C at a lower pressure of 10 atmospheres without changing the catalyst.

Using the equation for the reaction

calculate the maximum volume of products, in dm³, that could be formed by the complete reaction of 650 dm³ of methane.

(assume all volumes of gases are measured under the same conditions of temperature and pressure)

maximum volume of products =_........

Using the same equation for the reaction

calculate the maximum mass, in g, of carbon dioxide for every 1800 dm³ of hydrogen, measured at room temperature and pressure, produced in this reaction.

(relative formula mass: CO₂ = 44; 1 mol of any gas at room temperature and pressure occupies 24 dm³)

mass of carbon dioxide =_........

Buildings sometimes have water sprinklers to put out fires.

The pipes in some water sprinklers are filled with nitrogen gas to prevent corrosion when the system is not in use.

State what is meant by the term corrosion.

Nitrogen can be made from sodium azide, NaN₃.

Calculate the maximum volume, in cm³, of nitrogen produced from 110 g of sodium azide.

(relative formula mass: NaN₃ = 65;

1 mol of gas occupies 24 dm³ in the conditions used)

*(b) Compare and contrast the properties and uses of pure aluminium and pure copper with the alloys of aluminium and the alloys of copper.

Include in your answer an explanation of the similarities and the differences in the properties and the uses of a pure metal and its alloy.

When hydrogen is removed from an alkane, an alkene is formed.

This is an example of a dehydrogenation reaction.

Under certain conditions the dehydrogenation of propane forms propene and a dynamic equilibrium is reached.

State what is meant by dynamic in this context.

*(ii) The equation for this equilibrium reaction is

propane propene

The forward reaction takes in heat energy and is endothermic. A manufacturer produces large quantities of propene using this equilibrium reaction.

Suggest, with explanations, suitable conditions that the manufacturer could use to maximise the yield and rate of production of propene from propane.

C₃H₈(g) C₃H₆(g) + H₂(g) propane propene

State the maximum volume of propene, in dm³, formed by the dehydrogenation of 300 dm³ of propane.

(assume all volumes of gases are measured under the same conditions of temperature and pressure)

maximum volume of propene =_........

900 dm³ of propane, measured at room temperature and pressure, were dehydrogenated to form propene.

propane propene

Calculate the maximum mass, in kg, of hydrogen formed in this reaction.

(relative atomic mass: H = 1.0; 1 mol of any gas at room temperature and pressure occupies 24 dm³)

mass of hydrogen =_........

Hydrogen-oxygen fuel cells, rather than chemical cells, can be used to power some vehicles.

Give one advantage of using a hydrogen-oxygen fuel cell, rather than using a chemical cell, to power a vehicle.

Complete the half-equation for the reaction taking place at one of the electrodes in a hydrogen-oxygen fuel cell.

Calculate the volume of 48 g of oxygen at room temperature and pressure.

(relative atomic mass: O = 16, 1 mol of gas occupies 24 dm³ at room temperature and pressure)

volume of oxygen =_........

*(d) The hydrogen used in a hydrogen-oxygen fuel cell can be produced from methanol, CH₃OH.

In this reaction the forward reaction is endothermic and heat energy is taken in from the surroundings. The conditions used for this reaction are

• a nickel catalyst

• a temperature of 220 °C

Explain, in terms of their effects on the rate of attainment of equilibrium and the equilibrium yield of hydrogen, why the reaction is carried out using a catalyst at 220 °C rather than without a catalyst at a lower temperature.

Methane reacts with steam to form hydrogen and carbon dioxide.

The reaction takes place in two stages.

Stage 1 takes in heat energy, it is endothermic.

Explain the effect of increasing the temperature on the yield of the products of stage 1.

The overall equation for the process is

0.40 g of methane were fully reacted with steam to form carbon dioxide and hydrogen.

Calculate the maximum volume of hydrogen in dm³, measured at room temperature and pressure, that could be made in this reaction.

(relative formula mass: CH₄ = 16, 1 mol of any gas at room temperature and pressure occupies 24 dm³)

*(b) Hydrogen-oxygen fuel cells can be used to provide electrical energy in a spacecraft.

The reaction that takes place in the fuel cell is

hydrogen + oxygenwater

Evaluate the advantages and disadvantages of providing electrical energy in a spacecraft using hydrogen-oxygen fuel cells rather than chemical cells.

(a) Nitric acid can be titrated with a solution of ammonia.

State the type of reaction occurring when nitric acid reacts with ammonia.

What salt is formed in this reaction?

In one stage of the production of nitric acid, nitrogen oxide, NO, is reacted with oxygen to make nitrogen dioxide, NO₂.

Calculate the minimum volume of air, measured at room temperature and pressure, required to react with 1000 g nitrogen oxide to form nitrogen dioxide.

Assume that the air contains 20% oxygen by volume. (relative atomic masses: N = 14, O = 16 1 mol of gas occupies 24 dm³ at room temperature and pressure)

*(c) In another stage in the production of nitric acid, ammonia is reacted with oxygen to form nitrogen oxide and water.

Heat energy is given out when ammonia reacts with oxygen.

The conditions chosen for the reaction are

• excess air, rather than just the right amount

• a pressure of 10 atm, rather than atmospheric pressure

• a temperature of 900 °C, rather than room temperature.

Explain the effect of the conditions chosen on the equilibrium yield of nitrogen oxide and on the rate of attainment of equilibrium.

The industrial production of sulfuric acid involves several steps.

One of these steps is the reaction of sulfur dioxide, SO₂, with oxygen to form sulfur trioxide, SO₃.

What volume of sulfur trioxide, in dm³, is produced by the complete reaction of 750 dm³ of sulfur dioxide? (all volumes of gases are measured under the same conditions of temperature and pressure)

Calculate the volume of oxygen needed to react completely with 750 dm³ of sulfur dioxide. (all volumes of gases are measured under the same conditions of temperature and pressure)

Calculate the mass, in kilograms, of 750 dm³ of sulfur dioxide, measured at room temperature and pressure. (relative formula mass: SO₂ = 64; 1 mol of any gas at room temperature and pressure occupies 24 dm³)

*(d) The reaction to produce sulfur trioxide reaches an equilibrium.

The forward reaction is exothermic. The rate of attainment of equilibrium and the equilibrium yield of sulfur trioxide are affected by pressure and temperature.

A manufacturer considered two sets of conditions, A and B, for this reaction. In each case sulfur dioxide is mixed with excess oxygen. The manufacturer changed the temperature and the pressure and only used a catalyst in B. The sets of conditions A and B are shown in Figure 7.

The manufacturer chooses set of conditions B rather than set of conditions A.

Explain, by considering the effect of changing the conditions on the rate of attainment of equilibrium and on the equilibrium yield of sulfur trioxide, why the manufacturer chooses the set of conditions B rather than the set of conditions A.