Edexcel GCSE Combined Science Paper 3: Chemistry 1 Foundation June 2022 question paper 1SC0/1CF

Figure 1 shows a metal spoon and two test tubes being heated in a water bath.

One test tube contains a piece of chocolate, the other some liquid egg white.

After heating, the spoon, the chocolate and the egg white are allowed to cool to room temperature.

Figure 2 shows the state of the three different substances before heating, when hot and after cooling.

Describe the differences in the arrangement and movement of the particles in a solid and in a liquid.

difference in arrangement of particles

difference in movement of particles

What name is given to the process when the chocolate changes from a solid to a liquid?

Give a reason why the metal spoon has not changed state during the experiment.

Explain how we know the change to the egg white is a chemical change rather than a physical change.

Potable water is water that is suitable for drinking.

River water can be treated to make it potable. Chlorination, filtration and sedimentation are three of the processes involved in making the river water potable.

Which row of the table shows these three processes in the order in which they are carried out?

State the reason why chlorine is added during the water treatment.

Describe how sedimentation is carried out.

Figure 3 shows the results of an analysis of a sample of potable water.

Using this information, explain why this sample of potable water is not the same as pure water.

A student wanted to distil a sample of potable water. Figure 4 shows apparatus the student used.

Name the piece of equipment labelled X in Figure 4.

The student made an error when setting up the equipment in Figure 4. This error meant no water could be collected in the test tube.

Explain what the student needs to do so water can be collected.

An atom of aluminium has an atomic mass of 27.

Aluminium has an atomic number of 13.

State the number of electrons, neutrons and protons in this atom.

number of electrons =_........

number of neutrons =_........

number of protons =_........

Aluminium reacts with bromine to form aluminium bromide. A sample of aluminium bromide contains 1.35 g of aluminium atoms and 12.00 g of bromine atoms.

Calculate the empirical formula of this sample of aluminium bromide.

(relative atomic masses: A l = 27.0, Br = 80.0)

empirical formula =_........

Gallium is in the same group in the periodic table as aluminium and in the same period in the periodic table as bromine.

State in which group and period of the periodic table gallium can be found.

You may want to refer to the periodic table.

group =_........

period =_........

Gallium had not been discovered when Mendeleev created his first periodic table.

Figure 5 shows some properties of gallium that Mendeleev predicted and some of the actual properties of gallium.

Describe how Mendeleev predicted these properties of gallium.

3.14 g of solid copper sulfate was dissolved in water and made up to 250 cm³ of solution.

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

concentration =_........ g dm⁻³

Sodium hydroxide solution was added to a solution of copper sulfate. A precipitate of copper hydroxide and a solution of sodium sulfate were formed.

State what would be seen in the reaction.

Complete the balanced equation for the reaction by adding a number in front of NaOH.

_........ NaOH + CuSO₄ Cu(OH)₂ + Na₂SO₄

Describe how to obtain a pure, dry sample of the precipitate of copper hydroxide from the reaction mixture.

Figure 6 shows the equipment used to electrolyse a sample of sodium sulfate solution.

Graphite electrodes are used in the electrolysis of sodium sulfate solution. Graphite is used because it is inert and conducts electricity.

Figure 7 shows the ions in the sodium sulfate solution.

Draw a circle around each of the ions in Figure 7 that are attracted to the negative graphite electrode during the electrolysis.

State why it is important that the electrodes are inert.

Explain, in terms of its structure, how graphite conducts electricity.

Barium hydroxide reacts with dilute hydrochloric acid to form barium chloride and water.

The equation for the reaction is

Which row of the table shows the correct state of each of the substances in the equation for the reaction?

A student wanted to investigate how the pH of the mixture changes as barium hydroxide is added to dilute hydrochloric acid.

They followed this method.

step 1 measure out 50.0 cm3³ of dilute hydrochloric acid into a beaker using a measuring cylinder step 2 use a glass rod to place a drop of the acid onto a piece of universal indicator paper and record the pH step 3 add 0.2 g of barium hydroxide to the acid in the beaker and stir step 4 use the glass rod to place a drop of the mixture onto a new piece of universal indicator paper and record the pH again step 5 repeat steps 3–4 until there is no further change in the pH.

Name a piece of equipment which could be used to measure out 50.0 cm³ of dilute hydrochloric acid more accurately than the measuring cylinder.

Describe how the pH of the mixture is determined when a drop of it is placed on the universal indicator paper.

In the method, universal indicator paper is used to determine the pH.

Explain why litmus paper would not be a suitable indicator to use in this experiment.

Figure 8 shows the student’s results.

On the grid opposite:

• Add suitable scales to the vertical and horizontal axes.

• Plot a graph of the pH of the mixture against the mass of barium hydroxide.

Figure 9 shows a hazard symbol placed on a container of barium hydroxide.

What is the meaning of the hazard symbol in Figure 9?

Barium hydroxide is also corrosive.

Give one precaution that the student should take when using barium hydroxide.

Magnesium carbonate has the formula MgCO₃.

Magnesium carbonate contains Mg²⁺ and CO₃²⁻ ions.

The atomic number of magnesium is 12.

What is the electronic configuration of the Mg²⁺ ion?

Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium can.

Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO₃.

(relative atomic masses: C = 12.0, O = 16.0, Mg = 24.0)

percentage by mass of magnesium =_........

*(c) A student has two separate test tubes containing sulfuric acid.

The student adds a spatula measure of magnesium carbonate, MgCO₃, to the first test tube and a piece of magnesium to the second test tube.

Explain what the student would see in each test tube and the tests that they should carry out to identify the gases produced.

Your answer should include word equations for the reactions that would take place.