O Level Chemistry 5070 Paper 22, May/June 2024

is a catalyst in the Contact process

is a reducing agent in the blast furnace

changes from a white solid to a blue solid when water is added to it

kills microbes during the treatment of the domestic water supply

has the empirical formula ${\mathrm{C}\mathrm{H}}_2\mathrm{O}$.

Construct the symbol equation for this reaction.

Methane is a saturated hydrocarbon. Explain why methane is a hydrocarbon.

Explain why methane is saturated.

Methane reacts with chlorine in the presence of ultraviolet light. State the formulae of two products of this reaction.

Draw a dot-and-cross diagram to show the electronic configuration in a molecule of methane. Show only the outer shell electrons.

The equation for the complete combustion of methane is shown. $${\mathrm{C}\mathrm{H}}_4+2{\mathrm{O}}_2\to {\mathrm{C}\mathrm{O}}_2+2{\mathrm{H}}_2\mathrm{O}$$ This reaction is exothermic. Explain, using ideas about bond breaking and bond making, why this reaction is exothermic.

Complete the reaction pathway diagram in Fig. 2.1 for the complete combustion of methane. Label the: • reactants • products • enthalpy change of the reaction, $\mathrm{\Delta }H$ • activation energy, $E_{\mathrm{a}}$.

A $35.0{\mathrm{c}\mathrm{m}}^3$ sample of $0.266\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{/}{\mathrm{d}\mathrm{m}}^3$ ${\mathrm{H}}_2{\mathrm{O}}_2$ is completely decomposed. Calculate the volume of oxygen formed, measured at room temperature and pressure. Give your answer to two significant figures. volume of oxygen = ................................................. ${\mathrm{d}\mathrm{m}}^3$

Describe and explain the effect of decreasing the temperature on the rate of this reaction.

Describe and explain the effect of increasing the concentration of hydrogen peroxide on the rate of this reaction.

A sample of aqueous hydrogen peroxide has a pH of 5.5. State which ion is responsible for this pH value.

A pH meter is used to measure the pH of an aqueous solution. Describe one other way to measure the pH of an aqueous solution.

Explain why calcium bromide has a high melting point.

Describe how calcium atoms and bromine molecules react to form calcium ions and bromide ions. Use ideas about electron transfer.

Predict the products at each electrode during the electrolysis of dilute aqueous calcium bromide. at anode .................................................................................................................................... at cathode .................................................................................................................................

Ozone is an oxidising agent. Describe the colour change when ozone gas is bubbled through aqueous potassium iodide.

Zinc is a reducing agent. Describe the colour change when excess zinc is added to acidified potassium manganate(VII).

The ionic equation for the reaction between aqueous calcium bromide and aqueous chlorine is shown. $$2{\mathrm{B}\mathrm{r}}^{-}(\mathrm{a}\mathrm{q})+{\mathrm{C}\mathrm{l}}_2(\mathrm{a}\mathrm{q})\to {\mathrm{B}\mathrm{r}}_2(\mathrm{a}\mathrm{q})+2{\mathrm{C}\mathrm{l}}^{-}(\mathrm{a}\mathrm{q})$$ Explain, in terms of electrons, why this reaction involves both oxidation and reduction.

The temperature of the closed system is decreased and the pressure is kept constant. Predict how the position of equilibrium of this reaction is affected. Explain your answer.

The pressure of the closed system is increased and the temperature is kept constant. Predict how the position of equilibrium of this reaction is affected. Explain your answer.

Calculate the maximum mass of zinc oxide that can be made from $4.23\mathrm{g}$ of zinc carbonate. mass of zinc oxide = ...................................................... $\mathrm{g}$

Zinc oxide reacts with both aqueous sodium hydroxide and dilute hydrochloric acid, but carbon dioxide only reacts with aqueous sodium hydroxide. Explain why.

Solid zinc carbonate reacts with dilute nitric acid to give a colourless solution and bubbles of a gas. Construct the symbol equation for this reaction. Include state symbols.

Describe one adverse effect of higher levels of methane in air.

The combustion of fossil fuels that contain sulfur produces sulfur dioxide. Describe two strategies to reduce the emission of sulfur dioxide from the combustion of fossil fuels.

Nitrogen monoxide, $\mathrm{N}\mathrm{O}$, is linked to acid rain. This pollutant is present in the gases made in car engines. Describe how nitrogen monoxide is removed from these gases. Include a word equation in your answer.

State two other adverse effects of oxides of nitrogen pollutants in the air.

A sample of oxygen has a volume of $540{\mathrm{c}\mathrm{m}}^3$ at room temperature and pressure. The temperature of the sample is increased but the pressure is unchanged. Describe and explain, in terms of kinetic particle theory, what happens to the volume of the sample.

Sulfur is a gas above ${445}^{\circ }\mathrm{C}$. Describe the changes in particle separation, arrangement and motion when a sample of sulfur gas is cooled down to room temperature. separation ................................................................................................................................. ................................................................................................................................................... arrangement ............................................................................................................................. ................................................................................................................................................... motion ....................................................................................................................................... ...................................................................................................................................................

Describe diffusion in terms of kinetic particle theory.

The symbol of a sulfide ion is shown. $${}_{16}^{33}{\mathrm{S}}^{2-}$$ Complete Table 7.1 about this sulfide ion. Table 7.1

Draw the displayed formula of compound A.

State the name of ester B.

State the name of compound C.

Deduce the molecular formula of compound C.

State the name and formula of compound D. name ......................................................................................................................................... formula ......................................................................................................................................

State the formula of gas E and of liquid F. E ............................................................................................................................................... F ...............................................................................................................................................

Draw the structural formula of ester G.

Fig. 9.1 shows the equation for the reaction used to prepare a polymer. The monomer is both an alcohol and a carboxylic acid. Name the type of linkage that bonds the repeat units to one another in this polymer.

Explain how the equation shows that the polymer is made by a condensation reaction.

A polymer contains 10.8% carbon, 17.1% fluorine and 72.1% bromine by mass. Calculate the empirical formula of this polymer. empirical formula .............................................................

Some plastics are made from polymers that are hydrocarbons. There are many environmental challenges caused by plastics. Explain why there is an accumulation of plastics in the oceans. Use ideas about the properties of plastics.

Explain why the disposal of plastics causes an environmental challenge.