Edexcel GCSE Combined Science Paper 4: Chemistry 2 Foundation November 2021 question paper 1SC0/2CF

Magnesium reacts with dilute sulfuric acid to form magnesium sulfate and hydrogen gas.

A student wants to find out the effect of temperature on the rate of this reaction.

The student used the following method.

step 1pour 25 cm³ of dilute sulfuric acid into a conical flask step 2 warm the acid until its temperature is 30 °C step 3 add a piece of magnesium to the acid step 4 start a stopwatch step 5 wait until the reaction has finished step 6 stop the stopwatch step 7 repeat steps 1–6 but at 50 °C.

The student kept the volume of sulfuric acid the same when they repeated the method at 50 °C.

State two other variables that should be kept the same.

Which piece of equipment can be used to find the volume of 25 cm³ of sulfuric acid?

State how the student will know that the reaction has finished.

The reaction at 50 °C was faster than the reaction at 30 °C.

Give one reason, in terms of particles, why the reaction at 50 °C was faster than the reaction at 30C.

At 50 °C, 15.0 cm³ of gas was produced during the first 60 seconds of the reaction.

Calculate the average rate of reaction, in cm³ s^–1, for the first 60 seconds of the reaction.

average rate of reaction =_........ cm³ s^–1

This question is about the noble gases.

State, in terms of outer shell electrons, why the noble gases are unreactive.

Figure 1 shows an airship, filled with helium, floating above the ground.

Helium, hydrogen and krypton are gases. Figure 2 shows the reactivity and density, at room temperature and pressure, of helium, hydrogen and krypton.

The density of air is 0.001225 gcm^–3.

Helium is used in airships.

Explain why hydrogen and why krypton are not used in airships.

Mendeleev produced one of the earliest periodic tables.

State why he could not include any of the noble gases in his periodic table.

Figure 3 shows the boiling points of some of the noble gases.

Complete the bar chart to show the boiling points of neon and argon.

Predict the boiling point of xenon.

boiling point of xenon =_........ °C

Fluorine, chlorine, bromine and iodine are elements in group 7 of the periodic table.

State the name given to the group 7 elements.

Name one other element that is in group 7. Use the periodic table on the back of this exam paper to help you.

Which element is liquid at room temperature and pressure?

Which element is dark grey in colour at room temperature and pressure?

Tin reacts with chlorine to form tin chloride. A sample of tin chloride contains 1.19 g of tin and 1.42 g of chlorine.

Calculate the empirical formula of this tin chloride.

(relative atomic masses: C l = 35.5, Sn = 119.0)

You must show your working.

empirical formula of this tin chloride =_........

Tin also reacts with fluorine. The reaction between fluorine and tin is much more vigorous than the reaction between chlorine and tin.

Figure 4 shows the electronic configurations of fluorine and chlorine.

Explain, in terms of their electronic configurations, why fluorine reacts with tin more vigorously than chlorine reacts with tin.

Figure 5 shows a sample of hydrogen peroxide solution decomposing to form water and oxygen gas.

Write the word equation for hydrogen peroxide solution decomposing.

In this reaction hydrogen peroxide is a solution, water is a liquid and oxygen is a gas.

Draw one straight line from each substance to its correct state symbol.

Describe the test to show the gas produced is oxygen.

Figure 6 shows the electron arrangement for an atom of hydrogen and an atom of oxygen.

Complete the dot and cross diagram in Figure 7 for a molecule of water, H₂O.

Draw outer shell electrons only.

Liver contains the enzyme catalase.

A piece of liver was added to another sample of hydrogen peroxide solution.

Figure 8 shows the results.

Figure 9 shows a graph of the volume of oxygen produced from the hydrogen peroxide with and without liver.

Figure 9

Complete the missing label on the axis of the graph.

Describe what the graph shows about the difference in decomposition of hydrogen peroxide with and without liver.

Describe how the apparatus in Figure 8 could be modified to find the volume of gas produced when the liver is added to the hydrogen peroxide.

The concentration of a solution can be calculated using the equation

A student dissolved 9.25 g of ammonium chloride in water and made up the

Use the equation to calculate the concentration of this solution in gdm⁻³.

concentration =_........ g dm⁻³

Dissolving ammonium chloride in water is an endothermic process. Figure 10 shows part of the reaction profile for this process.

Explain how Figure 10 shows that dissolving ammonium chloride in water is an endothermic process.

Complete the reaction profile in Figure 10 and label the activation energy.

Ammonia gas is toxic.

Which symbol should be placed on a container of a toxic gas?

Give one safety precaution that should be taken when working with toxic gases in the laboratory.

Diesel oil is a mixture of hydrocarbons that can be obtained from crude oil.

State the name of the process used to separate diesel oil from crude oil.

Diesel oil contains alkanes. These alkanes are part of an homologous series.

Which statement about compounds in this homologous series is true?

When fuels such as diesel oil are burned, the high temperatures produced can cause nitrogen and oxygen in the air to form the pollutant nitrogen dioxide.

Complete the balanced equation for the reaction.

N₂ + 2O_{2 ........}

Explain how the greenhouse effect is caused by the gases produced by the complete combustion of diesel oil.

*(e) Diesel oil can contain impurities of sulfur. Burning diesel oil containing impurities of sulfur can result in acid rain. Acid rain is harmful to the environment.

Explain how acid rain is formed and the harm it can do.