IGCSE Chemistry 0620 Paper 33, May/June 2023

is present in diamond

forms an oxide that contributes to acid rain

has an atom with five occupied electron shells

forms an ion with a charge of 1 transport $\mathrm{/}1+1+$

forms an ion that gives a red-brown precipitate on addition of aqueous ammonia

is used in the manufacture of aircraft because of its low density.

Table 2.1 shows some properties of the halogens. Table 2.1 Use the information in Table 2.1 to predict: the boiling point of chlorine

the density of fluorine at room temperature and pressure

the physical state of iodine at $+{100}^{\circ }\mathrm{C}$. Give a reason for your answer. physical state ...................................................................................................................... reason ................................................................................................................................. .............................................................................................................................................

Aqueous chlorine reacts with aqueous sodium bromide. Complete the word equation for this reaction.

State a test for sodium ions. test ...................................................................................................................................... observations .......................................................................................................................

Polluted water can contain harmful substances such as metal compounds, nitrates and sewage. Name two other substances present in polluted water which are harmful to aquatic life. 1 .......................................................................................................................................... 2 ..........................................................................................................................................

State why sewage can cause disease.

Table 3.1 shows the masses of ions, in $\mathrm{m}\mathrm{g}$, present in $1000{\mathrm{c}\mathrm{m}}^3$ of polluted water. Answer these questions using information from Table 3.1. Name the positive ion present in the lowest concentration.

State the name of the ion ${\mathrm{S}\mathrm{O}}_4^{2-}$.

Calculate the mass of calcium ions present in $250{\mathrm{c}\mathrm{m}}^3$ of polluted water. mass = .............................. $\mathrm{m}\mathrm{g}$

Cobalt(II) chloride can be used to test for the presence of water. $${\mathrm{C}\mathrm{o}\mathrm{C}\mathrm{l}}_2(\mathrm{s})+6{\mathrm{H}}_2\mathrm{O}(\mathrm{l})\rightleftharpoons {\mathrm{C}\mathrm{o}\mathrm{C}\mathrm{l}}_2\cdot 6{\mathrm{H}}_2\mathrm{O}(\mathrm{s})$$ Describe how pink cobalt(II) chloride can be changed to blue cobalt(II) chloride.

Choose a word from the list which best describes pink cobalt(II) chloride. Draw a circle around your chosen answer. anhydrous hydrated liquid reduced

Iron reacts with steam to form ${\mathrm{F}\mathrm{e}}_3{\mathrm{O}}_4$ and a gas which pops with a lighted splint. Complete the symbol equation for this reaction. $$3\mathrm{F}\mathrm{e}+\dots \dots {\mathrm{H}}_2\mathrm{O}\to {\mathrm{F}\mathrm{e}}_3{\mathrm{O}}_4+4\dots \dots$$

Deduce the number of protons, neutrons and electrons in the bromide ion shown. ${}_{35}^{81}{\mathrm{B}\mathrm{r}}^{-}$ number of protons ..................................................................................................................... number of neutrons ................................................................................................................... number of electrons ...................................................................................................................

Hydrogen bromide decomposes to hydrogen and bromine when heated. Fig. 4.1 shows an incomplete reaction pathway diagram for this reaction. Complete Fig. 4.1 by writing these formulae on the diagram: ● $2\mathrm{H}\mathrm{B}\mathrm{r}$ ● ${\mathrm{H}}_2+{\mathrm{B}\mathrm{r}}_2$.

Explain how Fig. 4.1 shows that the reaction is endothermic.

Complete this sentence about an endothermic reaction using a word from the list. products reactants bromine surroundings An endothermic reaction transfers thermal energy from the ................................. .

Hydrobromic acid is formed when hydrogen bromide dissolves in water. Write the formula of the ion which is present in all acids.

Complete the word equation for the reaction of any acid with any carbonate.

A few drops of litmus indicator are added to a dilute acid. State the colour of the solution.

Fig. 4.2 shows the apparatus used for the electrolysis of molten lead(II) bromide using graphite electrodes. Label Fig. 4.2 to show: ● the cathode ● the electrolyte.

Name the products and state the observations at the positive and negative electrodes. product at the positive electrode ............................................................................................................................................. observations at the positive electrode ............................................................................................................................................. product at the negative electrode ............................................................................................................................................. observations at the negative electrode .............................................................................................................................................

State one property of graphite that makes it useful as an electrode.

Nickel is a transition element. Sodium is an element in Group I of the Periodic Table. State two differences in the physical properties of nickel compared to sodium. 1 ................................................................................................................................................. 2 .................................................................................................................................................

Stainless steel is an alloy that is used to make cutlery. Give one reason why stainless steel is used to make cutlery.

Table 5.1 shows some information about the reaction of four metals with oxygen. Table 5.1 Put the four metals in order of their reactivity. Put the least reactive metal first.

Complete the diagram in Fig. 5.1 to show the electronic configuration of a magnesium atom.

A student investigates the reaction of magnesium with dilute hydrochloric acid at three different temperatures. The temperatures are: ● ${20}^{\circ }\mathrm{C}$ ● ${30}^{\circ }\mathrm{C}$ ● ${40}^{\circ }\mathrm{C}$. All other conditions stay the same. Table 6.1 shows the time taken for each reaction to finish. Table 6.1 Complete Table 6.1 by writing the temperatures in the first column.

Describe the effect on the time taken for the magnesium to finish reacting with dilute hydrochloric acid when the surface area of the magnesium is increased. All other conditions stay the same.

Describe the effect on the time taken for the magnesium to finish reacting with dilute hydrochloric acid when the concentration of acid is decreased. All other conditions stay the same.

Describe how crystals of magnesium chloride can be prepared after reacting excess magnesium with dilute hydrochloric acid.

Magnesium chloride is soluble in water. Choose one other compound that is soluble in water. Tick (✓) one box. ammonium sulfate calcium carbonate iron(II) hydroxide silver chloride

Fig. 7.1 shows the displayed formula of compound E. On Fig. 7.1 draw a circle around the functional group that makes compound E unsaturated.

Deduce the molecular formula of compound E.

Describe a chemical test to distinguish between a saturated and an unsaturated compound. test ...................................................................................................................................... observations with saturated compound .............................................................................. ............................................................................................................................................. observations with unsaturated compound .......................................................................... .............................................................................................................................................

Alcohols have an –OH functional group. Write the general formula for the alcohol homologous series.

Ethanol is an alcohol with two carbon atoms in each molecule. Draw the displayed formula of ethanol.

Ethanol reacts to form a compound with the formula ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_2$. Complete Table 7.1 to calculate the relative molecular mass of ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_2$. Table 7.1 relative molecular mass = ..............................

Ethanol can be manufactured by the fermentation of aqueous glucose. State two conditions for fermentation. 1 ................................................................................................................................................. 2 .................................................................................................................................................

Ethanol can be oxidised to ethanoic acid. Complete the word equation for the reaction of ethanoic acid with sodium.

Non-metals are poor thermal conductors. Describe two other physical properties which are typical of non-metals. 1 ................................................................................................................................................. 2 .................................................................................................................................................

Carbon dioxide contributes to increased global warming which leads to climate change. State two strategies which help to reduce climate change caused by carbon dioxide. 1 ................................................................................................................................................. 2 .................................................................................................................................................

Water is a simple molecular compound. Complete Fig. 8.1 to show the dot-and-cross diagram for a molecule of water. Show outer shell electrons only. Fig. 8.1

State two properties of simple molecular compounds. 1 .......................................................................................................................................... 2 ..........................................................................................................................................

Water is a good solvent. State the meaning of the term solvent.

Pure water has a neutral pH value. Choose from the list, the pH value that is neutral. Draw a circle around your chosen answer. pH 1 pH 3 pH 7 pH 14

A crystal of blue copper(II) sulfate is placed at the bottom of a beaker of water as shown in Fig. 8.2. Fig. 8.2 After one day, the blue colour has spread throughout the water in the beaker. Explain these results in terms of the kinetic particle theory.