IGCSE Chemistry 0620 Paper 42, May/June 2024

State one gas which: is the main constituent of natural gas

State one gas which: is responsible for both photochemical smog and acid rain

State one gas which: is unsaturated

State one gas which: has monatomic particles

State one gas which: reduces iron(III) oxide in a blast furnace.

Nitrogen dioxide, ${\mathrm{N}\mathrm{O}}_2$, and carbon monoxide are removed from a car exhaust by a catalytic converter. Write the symbol equation for this reaction.

All metals form positive ions. Describe how atoms form positive ions.

State which of the five metals in the list has the greatest tendency to form positive ions.

Suggest one of the five metals in the list which is not likely to show catalytic properties.

State which of the five metals in the list is a major component of stainless steel.

A student adds a sample of a metal to an aqueous metal salt in a beaker to see if a displacement reaction takes place. Complete Table 2.1 to show the colour of the solution in the beaker at the start and at the end of the experiment. Table 2.1

Most Group II metals form a gas when placed into cold water. An alkaline solution is also formed. Name the gas formed when strontium is added to cold water.

Name the alkaline solution formed when strontium is added to cold water.

One Group II metal reacts very slowly when placed in cold water. When heated, the metal reacts with steam to form a white solid. Identify this metal and name the white solid formed. metal ................................................................................................................................... white solid ...........................................................................................................................

Under certain conditions, iron will react with steam to form an oxide of iron with the formula ${\mathrm{F}\mathrm{e}}_3{\mathrm{O}}_4$. ${\mathrm{F}\mathrm{e}}_3{\mathrm{O}}_4$ reacts with dilute hydrochloric acid to form a mixture of iron(II) and iron(III) salts and water. Deduce the symbol equation for the reaction between ${\mathrm{F}\mathrm{e}}_3{\mathrm{O}}_4$ and dilute hydrochloric acid.

Name this industrial process.

State the meaning of $\mathrm{\Delta }H$.

State the typical conditions and name the catalyst used in the industrial production of ammonia. temperature and units ........................................ pressure and units ............................................. catalyst used ......................................................

State two methods of increasing the rate of this reaction. 1 ................................................................................................................................................. 2 .................................................................................................................................................

The symbol equation for the reaction can be represented as shown in Fig. 3.1. Table 3.1 shows some bond energies. Table 3.1

Use the bond energies in Table 3.1 and $\mathrm{\Delta }H$ to calculate the bond energy of an $\mathrm{N}-\mathrm{H}$ bond, in $\mathrm{k}\mathrm{J}\mathrm{/}\mathrm{m}\mathrm{o}\mathrm{l}$. Use the following steps. • Calculate the energy needed to break bonds in the reactants. .............................. kJ • Calculate the energy released when bonds form in the products. .............................. kJ • Calculate the energy of an $\mathrm{N}-\mathrm{H}$ bond. .............................. kJ/mol

An incomplete symbol equation for the preparation of ammonia in the laboratory is shown. $$\mathrm{C}\mathrm{a}\mathrm{O}+2{\mathrm{N}\mathrm{H}}_4\mathrm{C}\mathrm{l}\to {\mathrm{C}\mathrm{a}\mathrm{C}\mathrm{l}}_2+\text{.........................}+2{\mathrm{N}\mathrm{H}}_3$$ Complete the symbol equation.

Name ${\mathrm{N}\mathrm{H}}_4\mathrm{C}\mathrm{l}$.

Calculate the volume of ammonia, ${\mathrm{N}\mathrm{H}}_3$, measured at room temperature and pressure, which forms when $1.12\mathrm{g}$ of $\mathrm{C}\mathrm{a}\mathrm{O}$ is heated with excess ${\mathrm{N}\mathrm{H}}_4\mathrm{C}\mathrm{l}$. [$M_{\mathrm{r}}$: $\mathrm{C}\mathrm{a}\mathrm{O}$, 56]

Deduce the empirical formula of the ester.

Name the ester.

Name carboxylic acid $\mathbf{X}$ and draw its displayed formula. name .......................................................................................................................................... displayed formula

Name alcohol $\mathbf{Y}$ and give its structural formula. name .......................................................................................................................................... structural formula .......................................................................................................................

Complete Table 4.1 to show the effect, if any, for each change of condition. Table 4.1

At the beginning of the reaction between the ester and water, no carboxylic acid is present in the reaction mixture. Suggest how the pH of the reaction mixture changes from the start of the reaction until equilibrium is reached. Assume alcohols and esters are neutral. pH at start of reaction ......................................................................................................... pH at equilibrium .................................................................................................................

Identify the ion that causes the change in pH.

Name an indicator which can be used to follow the change in pH.

A sample of sulfur contains two isotopes, ${}^{32}\mathrm{S}$ and ${}^{34}\mathrm{S}$. Complete Table 5.1 to show the number of protons and neutrons in one atom of each isotope of sulfur. Table 5.1

State why these isotopes have identical chemical properties.

State the mass of $6.02\times {10}^{23}$ atoms of ${}^{34}\mathrm{S}$. Include units in your answer.

State the name of the amount of substance which contains $6.02\times {10}^{23}$ atoms.

Table 5.2 shows the relative abundance of these isotopes of sulfur in the sample. Table 5.2

Calculate the relative atomic mass of sulfur in this sample to one decimal place.

Sulfur reacts with magnesium to form magnesium sulfide, $\mathrm{M}\mathrm{g}\mathrm{S}$, an ionic compound. Complete the dot-and-cross diagram in Fig. 5.1 of the ions in magnesium sulfide. Give the charges on the ions.

State why $\mathrm{M}\mathrm{g}\mathrm{S}$ has a high melting point.

State why molten $\mathrm{M}\mathrm{g}\mathrm{S}$ conducts electricity.

An acid containing sulfur reacts with sodium hydroxide, $\mathrm{N}\mathrm{a}\mathrm{O}\mathrm{H}$, to form a salt and water. The salt has the formula ${\mathrm{N}\mathrm{a}}_2{\mathrm{S}\mathrm{O}}_3$. Deduce the formula of this acid.

Deduce the formula of the anion in ${\mathrm{N}\mathrm{a}}_2{\mathrm{S}\mathrm{O}}_3$.

${\mathrm{N}\mathrm{a}}_2{\mathrm{S}\mathrm{O}}_3$ is oxidised by acidified aqueous potassium manganate(VII). State what VII refers to in the name potassium manganate(VII).

State the colour change when this reaction happens. from ............................................................ to .............................................................

Glucose, ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$, is made in plants from carbon dioxide and water. Name this process.

Write the symbol equation for this process.

State two essential conditions needed for this process to happen. 1 .......................................................................................................................................... 2 ..........................................................................................................................................

Glucose is converted to ethanol. Name this process.

Name the other product formed when glucose is converted to ethanol.

Ethanol is made by reacting ethene with steam in an industrial process. State the conditions and type of catalyst used in this industrial production of ethanol. temperature and units ........................................... pressure and units ................................................ type of catalyst used .............................................

Explain why this reaction is an addition reaction.

Complete the dot-and-cross diagram in Fig. 6.1 of a molecule of ethanol.