Edexcel GCSE Combined Science Paper 4: Chemistry 2 Higher June 2022 question paper 1SC0/2CH

A student used the apparatus in Figure 1 to investigate the rate of the reaction between a metal and dilute hydrochloric acid.

Pieces of the metal were placed in dilute hydrochloric acid in the flask, and the total volume of gas produced was measured every minute.

Figure 2 shows a graph of the student’s results.

Name a piece of apparatus that would be better to measure the volume of gas produced, instead of the 250 cm³ measuring cylinder.

Give a reason for your answer.

name of apparatus

reason

Calculate the mean rate of production of hydrogen over the first 90 seconds, in cm³ per second.

rate =_........ cm³ per second

The student measured the volume of gas for 10 minutes.

State why the measurements could have been stopped at 9 minutes.

The experiment was repeated, but with acid of a higher concentration.

The rate of reaction was faster.

Explain why the rate of reaction increases when the concentration of acid is increased.

Another student suggests four other ways of increasing the rate of this reaction.

Which one is correct?

This question is about gases.

When sodium is added to water, hydrogen gas is produced.

Which observation shows that a gas has been produced?

Some damp litmus paper is placed in a gas. The litmus paper is bleached.

Which gas bleaches damp litmus paper?

When calcium carbonate is heated it decomposes.

When 5.000 g of calcium carbonate is heated, the mass of solid remaining is 2.800 g.

Calculate the mass of carbon dioxide that has been released.

Give your answer to three significant figures.

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

A diagram of an atom of helium is shown in Figure 3.

Explain, using Figure 3, why helium is inert.

Helium is used to fill balloons.

State one property of helium, apart from it being inert, that makes it suitable for filling balloons.

Oxygen gas has the formula O₂.

Calculate the number of oxygen atoms in 3.50 mol of oxygen gas.

(Avogadro constant = 6.0210²³)

number of oxygen atoms =_........

Figure 4 shows some information about the composition of pollutant exhaust gases from the engines of two different vehicles.

Give two ways in which the data in Figure 4 shows that the diesel engine is more damaging to the environment than the petrol engine.

Explain, using information from Figure 4, one way in which the diesel engine is less damaging to the environment than the petrol engine.

Which statement about the members of the alkane homologous series is correct?

Write the balanced equation for the complete combustion of octane, C₈H₁₈.

The elements in group 7 of the periodic table are known as the halogens.

Name the halogen that is in period 4 of the periodic table.

Explain why chlorine is more reactive than iodine.

A piece of burning sodium is placed into a gas jar containing chlorine gas, as shown in Figure 5.

At the end of the reaction, the inside of the gas jar is coated with white crystals.

Identify the white crystals.

Sodium also reacts with bromine.

Write the balanced equation for the reaction between sodium and bromine.

In another experiment, a student adds colourless sodium bromide solution to chlorine water.

State what you would see in this reaction.

The ionic equation for the reaction between sodium bromide and chlorine is:

Explain which species has been oxidised in this reaction.

This question is about oxygen.

The percentage of oxygen in today’s atmosphere is greater than the percentage of oxygen in the Earth’s early atmosphere.

Explain what caused this change to happen.

Magnesium reacts with oxygen from the air to form magnesium oxide.

A student carries out an investigation to determine the mass of magnesium oxide formed when a known mass of magnesium reacts completely with oxygen.

This is the method the student used.

step 1 find the mass of a crucible and lid

step 2 put a known mass of magnesium into the crucible and put the lid on

step 3 heat for five minutes using a roaring Bunsen burner flame

step 4 let the crucible, lid and contents cool down

step 5 find the final mass of the crucible, lid and contents

Explain how the student could check that the magnesium had reacted completely with oxygen.

In another experiment, it was found that 1.24 g of phosphorus reacted completely with 1.60 g of oxygen to form phosphorus oxide.

The relative formula mass of this phosphorus oxide is 284.

Deduce the molecular formula of this phosphorus oxide.

You must show your working.

(relative atomic masses: O = 16, P = 31)

molecular formula =_........

A student uses the apparatus shown in Figure 6 to investigate the percentage of oxygen in the atmosphere.

The apparatus was left for a few days.

Explain one change the student would see after a few days.

Explain one change that can be made to the apparatus in Figure 6 to allow the student to calculate the percentage of oxygen in the atmosphere.

In some chemical reactions, bonds are broken in the reactant molecules and new bonds are formed to make the product molecules.

Which row is correct about the energy changes for these processes?

Hydrogen reacts with fluorine.

Figure 7 shows the bond energies for the bonds in the three molecules in the equation.

Calculate the energy change for this reaction.

energy change =_........ kJ mol

*(b) The reaction profile for an uncatalysed exothermic reaction is shown in Figure 8.

Using some examples of catalysts you have met in chemistry, discuss what catalysts do and their effect on the activation energy of a reaction.

You can use Figure 8 to illustrate your answer.