Edexcel GCSE Combined Science Paper 4: Chemistry 2 Foundation June 2018 question paper 1SC0/2CF

Students are investigating exothermic and endothermic reactions. They are finding the temperature change in 50 cm³ water when a solid dissolves in it. The apparatus is shown in Figure 1.

The dissolving of this solid in water is an exothermic change. The experiment is repeated a number of times. Compared with the initial temperature of the water, the final temperature of the solution is

State how step R could be changed to measure the volume of water more accurately.

Figure 2 shows a cold pack.

When the pack is squeezed hard the inner bag bursts. Then the pack goes cold.

Explain why the pack goes cold.

Give the reason why the pack can be used only once.

Hydrogen peroxide decomposes to form water and oxygen.

The rate of this reaction can be found by measuring the volume of oxygen formed after different time intervals.

Hydrogen peroxide solution is placed in a conical flask. The apparatus is set up as shown in Figure 3.

State the name of the piece of apparatus labelled Z in Figure 3.

At the end of the reaction the bung is removed from the conical flask. A glowing splint is put into the gas in the flask.

State what you would see.

A solid catalyst can be used for this reaction.

A given mass of catalyst is more effective if it has a large surface area.

State how you could increase the surface area of some lumps of solid catalyst.

The experiment is repeated three times once using a more dilute solution of hydrogen peroxide once using a lower temperature once using a larger flask

In each case, all other conditions are kept the same.

Circle the word that shows the change in the rate of decomposition in each case.

Complete the balanced equation for the reaction and fill in the two missing state symbols.

_........ H₂O₂(aq) 2H₂O(_........ ) + O₂(_........ )

Crude oil is found in the Earth’s crust.

Which of the statements about crude oil is correct?

The substances ethane, C₂H₆, octane, C₈H₁₈, and pentadecane, C₁₅H₃₂, are all found in crude oil.

These substances

Use a word from the box to complete each of the sentences about the fractional distillation of crude oil.

Each word may be used once, more than once, or not at all.

The separation of crude oil into fractions occurs in a fractional distillation column.

Before crude oil is passed into the column it is_........ .

During the distillation, vapour rises up the column until it is cold enough for the

vapour to form a liquid. The vapour has been_........ .

In January 2015 the United Kingdom produced 850 000 barrels of crude oil per day. 45% of this crude oil was fuel oil.

Calculate the number of barrels of fuel oil present in the 850 000 barrels of crude oil.

Give your answer to two significant figures.

_........ barrels

Figure 5 shows one molecule of each of four different substances, A, B, C and D.

substance A substance B substance C substance D

Figure 5

State the formula of a molecule of substance B.

Substance C can be formed by burning an element in oxygen.

Write the word equation for this reaction.

Consider substances A, B, and D.

Give the letters of the two substances that can be formed by burning an element in oxygen.

The amount of oxygen in the atmosphere has increased since the Earth’s early atmosphere was formed.

Explain what has caused this change.

Figure 6 shows a graph of the amount of carbon dioxide in the Earth’s atmosphere from 1985 to 2005.

Describe how the amount of carbon dioxide in the Earth’s atmosphere varies within each year.

Describe the overall trend in the amount of carbon dioxide in the Earth’s atmosphere from 1985 to 2005.

Calculate the change in the amount of carbon dioxide in the Earth’s atmosphere from the beginning of 1990 to the beginning of 2000.

change in amount =_........ ppm

(a) A chlorine atom contains 17 electrons, 18 neutrons and 17 protons.

State the mass number of this chlorine atom.

Give the electronic configuration of this chlorine atom.

Describe what you would see if damp, blue litmus paper is placed into chlorine gas.

Chlorine exists as diatomic molecules.

In a molecule, two chlorine atoms are joined by a covalent bond.

Describe what is meant by a covalent bond.

Explain why chlorine is a gas, rather than a liquid, at room temperature.

When the gas hydrogen chloride, HC l, is dissolved in water, a solution forms. Blue litmus paper dipped in this solution turns red.

State why the litmus paper turns red.

Figure 7 lists the halogens in the order in which they appear in group 7 of the periodic table.

The melting points of four of the halogens are given.

Estimate the melting point of iodine.

_........ °C

Bromine reacts with heated iron.

Give the name of one halogen that would react with iron more vigorously than bromine.

Lithium, sodium and potassium are reactive metals in group 1 of the periodic table.

Sodium metal tarnishes in air to form a layer of sodium oxide on its surface. 0.92 g of sodium combined with 0.32 g of oxygen in this oxide.

Calculate the empirical formula of this sodium oxide. (relative atomic masses: O = 16, Na = 23)

You must show your working.

empirical formula of sodium oxide =_........

Sodium reacts with water to form sodium hydroxide in solution and hydrogen.

Complete the balancing of the equation for this reaction and add the state symbols for each substance.

_........ Na(_........ ) + 2H₂O(_........ ) _........ NaOH(_........ ) + H₂(_........ )

In an experiment equal-sized pieces of lithium, sodium and potassium are added to separate samples of water.

A flame is produced only with potassium because potassium