5070/21 · Oct/Nov 2025
Download PDFChoose from the following compounds to answer the questions. compound A compound B compound C cyclo- compound D compound E compound F compound G Each compound can be used once, more than once or not at all.
State which compound: (i) is methanol
State which compound: (ii) is manufactured by the fermentation of aqueous glucose
State which compound: (iii) is a carboxylic acid
State which compound: (iv) is a saturated hydrocarbon
State which compound: (v) is formed by the reaction between methanol and propanoic acid.
State which two compounds have the same molecular formula.
A sample of sulfur found on the planet Mars contains four isotopes. Table 2.1 shows the percentage abundances of these four isotopes. Table 2.1
| isotope | percentage abundance |
| 95.04 | |
| 0.75 | |
| 4.20 | |
| 0.01 |
Describe one difference between the isotopes and .
Explain why all the isotopes of sulfur have the same chemical properties.
Show by calculation that the relative atomic mass of sulfur for this sample is 32.09.
Sodium hydrogencarbonate decomposes when heated.
Fig. 3.1 shows the reaction pathway diagram for the decomposition of sodium hydrogencarbonate. Identify the energy changes labelled A and B. energy change A ............................................................................................................... energy change B ...............................................................................................................
Use the reaction pathway diagram to explain why the decomposition of sodium hydrogencarbonate is endothermic.
Describe a chemical test for carbon dioxide. test ............................................................................................................................................ observation if carbon dioxide present .......................................................................................
A sample of sodium hydrogencarbonate is completely decomposed. A total volume of of carbon dioxide, measured at r.t.p., is produced. Calculate the mass of the sample of sodium hydrogencarbonate. Give your answer to two significant figures.
Fluorine, chlorine, bromine and iodine are elements in Group VII.
Bromine has a low boiling point. It is a liquid at room temperature. Describe the arrangement and motion of molecules in liquid bromine.
Explain why bromine has a low boiling point. Use ideas about structure and bonding.
Fluorine reacts with potassium to make the ionic compound potassium fluoride. Suggest two physical properties of potassium fluoride.
Construct the ionic half-equation to show the formation of potassium ions from potassium atoms.
Construct the ionic half-equation to show the formation of fluoride ions from fluorine molecules.
Chlorine gas is bubbled into aqueous potassium iodide. A reaction takes place. Chlorine is an oxidising agent. Name the two products of this reaction.
Describe the observations made during the reaction.
Nickel is a transition element.
Nickel has good electrical conductivity and good thermal conductivity. Nickel is also ductile and malleable. State two other physical properties of nickel that are typical of a transition element.
The physical properties of nickel can be explained using ideas about structure and bonding. Explain why nickel has good electrical conductivity.
Explain why nickel is ductile.
Compound X contains nickel, carbon and oxygen only. X contains 28.1% by mass carbon and 37.4% by mass oxygen. Calculate the empirical formula of compound X.
Nickel reacts slowly with dilute hydrochloric acid to form aqueous nickel(II) ions and hydrogen. Construct the ionic equation for this reaction. Include state symbols in your answer.
Predict if nickel reacts with aqueous copper(II) ions. Explain your answer. prediction ............................................................... explanation ........................................................................................................................
This question is about an unsaturated hydrocarbon called ethyne. Fig. 6.1 shows the displayed formula of ethyne. Fig. 6.1
Draw a dot-and-cross diagram to show the electronic arrangement in a molecule of ethyne. Include only the outer shell electrons of each atom.
A sample of ethyne gas has a mass of . Calculate the number of molecules of ethyne in this sample. One mole of ethyne contains molecules.
Calculate the total number of atoms in this sample of ethyne.
Explain why ethyne is a hydrocarbon.
Suggest the observations when ethyne gas is bubbled into aqueous bromine.
Ethyne is formed when calcium carbide reacts with water. Calcium carbide contains the ions and only. Deduce the formula of calcium carbide.
Ethene is used to make ethanol and poly(ethene). Fig. 7.1 shows the displayed formula of ethene.
Alkenes such as ethene are manufactured from hydrocarbons such as . Name this process.
Describe the conditions used in this process.
Ethene reacts with steam to make ethanol. This is a reversible reaction. Describe and explain the effect of increasing the temperature on the rate of the forward reaction.
Describe and explain the effect of increasing the pressure on the position of equilibrium while keeping the temperature constant.
Ethene is used to make the polymer poly(ethene). This polymer is used to make plastics. Draw the structure of poly(ethene). Your structure should show two repeat units.
State two environmental challenges caused by the disposal of poly(ethene).
Ethene reacts with hydrogen in the presence of a nickel catalyst. Explain why this is an example of an addition reaction.
Draw the displayed formula of the product of this reaction.
Petroleum is a mixture of hydrocarbons most of which are alkanes. Table 8.1 shows some of the unbranched alkanes present in petroleum and the number of carbon atoms in one molecule of the alkane. Table 8.1
| name | number of carbon atoms in one molecule of the alkane |
| decane | 10 |
| ethane | 2 |
| methane | 1 |
| pentane | 5 |
| tetradecane | 14 |
Deduce the molecular formula of tetradecane.
State the name of the alkane in Table 8.1 that has the highest viscosity.
Petroleum is separated into useful fractions by fractional distillation. Explain how petroleum is separated by fractional distillation.
Methane and ethane are both in the refinery gas fraction. State one use for the refinery gas fraction.
Decane is in the naphtha fraction. State one use for the naphtha fraction.
Anhydrous copper(II) sulfate is a white solid.
State the meaning of the term anhydrous.
Anhydrous copper(II) sulfate is added to water. State the colour of the solution formed.
Aqueous ammonia is added dropwise until in excess to a small volume of aqueous copper(II) sulfate. Describe the observations during this addition.
Describe the observations when aqueous barium nitrate is added to aqueous copper(II) sulfate.
Aqueous copper(II) sulfate is electrolysed separately with carbon electrodes and with copper electrodes. Complete Table 9.1. Table 9.1
Explain why aqueous copper(II) sulfate conducts electricity but solid copper(II) sulfate does not conduct electricity.
Air is a mixture of gases.
State the percentage by volume of oxygen in clean, dry air.
The percentage of carbon dioxide in air is increasing. State one adverse effect of this increasing percentage of carbon dioxide.
State one strategy to reduce this increase in the percentage of carbon dioxide.
Some air pollutants such as sulfur dioxide cause acid rain. Name one other air pollutant that causes acid rain.
The burning of fossil fuels containing sulfur in power stations produces sulfur dioxide emissions. Describe one way these sulfur dioxide emissions are reduced.