Edexcel GCSE Combined Science Paper 3: Chemistry 1 Higher November 2020 question paper 1SC0/1CH

Figure 1 shows the apparatus that can be used to electrolyse sodium sulfate solution using inert electrodes.

Hydrogen is produced at the negative electrode during electrolysis.

Describe the test to show the gas is hydrogen.

What is the name of gas X that forms at the positive electrode?

State what is meant by the term electrolysis.

The sodium sulfate solution was made by dissolving 28.4 g of sodium sulfate in water to make 250 cm³ of solution.

Calculate the concentration of this solution in g dm⁻³.

Give your answer to three significant figures.

concentration =_........ g dm

The word equation for the reaction between copper carbonate and dilute sulfuric acid is

copper sulfuric copper carbon

Complete the balanced equation for this reaction.

CuCO₃+_{........ ........} + CO₂+ H₂O

Calculate the relative formula mass of copper carbonate, CuCO₃. (relative atomic masses: C = 12.0, O = 16.0, Cu = 63.5)

relative formula mass of CuCO₃ =_........

What is the chemical test to show that a gas is carbon dioxide?

Figure 2 shows a conical flask containing dilute sulfuric acid. Copper carbonate is added to the acid in the flask. The copper carbonate is added one spatula measure at a time until the reaction has finished.

State two observations that would show the reaction has finished.

The electronic configuration of carbon is 2.4 The electronic configuration of oxygen is 2.6

Draw a dot and cross diagram for a molecule of carbon dioxide.

Show outer electrons only.

A sample of rock salt contains a mixture of sodium chloride and some insoluble substances.

The rock salt is added to water and the mixture stirred.

The mixture is then filtered to obtain a filtrate of sodium chloride solution.

Draw a labelled diagram of the apparatus used to filter the mixture and collect the sodium chloride solution.

Describe how a sample of pure, dry sodium chloride crystals can be obtained from the filtrate.

Inks contain coloured dyes. Samples of four inks, W, X, Y and Z, were separated using paper chromatography. Figure 3 shows the chromatogram obtained.

In the experiment, the solvent front moved 6.5 cm. Calculate the R_f value of the dye that is present in both inks X and Z.

R_f =_........

State what could be changed in the experiment to make the R_f value more accurate.

In this experiment, ink sample Y did not move from the start line. Explain a change to the experiment that would be needed to separate the dyes in ink sample Y.

Titanium and iron are examples of transition metals.

Figure 4 shows the percentage abundance of each isotope in a sample of titanium.

Calculate the relative atomic mass of titanium in this sample.

relative atomic mass =_........

Iron, when heated in air, reacts with oxygen to form iron oxide.

This reaction is an example of

The equipment shown in Figure 5 can be used to find the mass of oxygen that combines with iron.

Describe how the equipment shown in Figure 5 could be used to find the mass of oxygen that combines with 0.500 g of iron wool in a crucible and lid of known mass.

2.24 g of iron combines with 0.96 g of oxygen to form an oxide of iron.

Determine the formula of this oxide of iron and use it to complete the balanced equation.

(relative atomic masses: Fe = 56.0, O = 16.0)

You must show your working.

balanced equation for the reaction is

_........ Fe +_........ O_{2 ........}

Calcium has an atomic number of 20. A calcium atom has a mass number of 40.

Which row of the table shows the number of protons and number of neutrons in this atom of calcium?

Figure 6 shows the arrangement of electrons in an atom of calcium.

Explain, using the information in Figure 6, in which period of the periodic table calcium can be found.

Calcium and potassium react with water in similar ways.

One similarity in the reactions is that hydrogen gas is produced.

State one other similarity in the products of the reactions of calcium and potassium with water.

Potassium is higher in the reactivity series than calcium and reacts more vigorously with water than calcium reacts with water.

State why potassium is higher in the reactivity series and reacts more vigorously with water than calcium.

*(c) Calcium chloride can be prepared by the reaction of calcium with chlorine gas.

Figure 7 shows some properties of calcium, chlorine and calcium chloride.

Explain, in terms of bonding and structure, why the properties of the product, calcium chloride, are different from the properties of the reactants, calcium and chlorine.

Dilute hydrochloric acid is a strong acid.

Explain why dilute hydrochloric acid is described as a strong acid.

1 cm³ of hydrochloric acid of pH 2 is made up to a volume of 10 cm³ with distilled water.

State the pH of the new solution.

pH =_........

Magnesium oxide reacts with dilute hydrochloric acid to produce magnesium chloride solution and water.

Write the ionic equation for this reaction.

In an experiment magnesium hydroxide powder is added in 0.1 g portions to 25 cm³ of dilute hydrochloric acid until the magnesium hydroxide is just in excess.

Universal indicator paper can be used to test the pH of the solution after each addition of magnesium hydroxide.

Give the name of an alternative piece of equipment that can be used to measure pH.

State and explain how the pH changes as the magnesium hydroxide is added to the dilute hydrochloric acid.