AQA · GCSE · Chemistry

Energy changes

04.2 · 4 marks Explaining a zinc temperature graph Explain the results shown in Figure 3. Do not refer to anomalous points. Use data from Figure 3. 04.3 · 2 marks Thermal insulation in calorimetry Explain why using a polystyrene cup gives more accurate results than using a glass beaker. 04.6 · 1 mark Explaining random experimental errors The results show random errors. The student did not make any measuring errors. Suggest one reason for the random errors in this... 06.1 · 3 marks Ordering metals using cell voltages Write the symbols of the five metals in Table 3 in order of reactivity. Justify your answer. 06.2 · 6 marks Planning a chemical-cell concentration experiment The voltage produced by a chemical cell depends on the concentration of the electrolyte solution. Plan an experiment to... 08.2 · 1 mark Selecting an exothermic reaction profile Figure 8 shows four reaction profiles. Which is the correct reaction profile and labels for the reaction between propane and... 08.3 · 5 marks Calculating an unknown C—H bond energy Figure 9 shows the displayed formula equation for the reaction between propane and oxygen. The overall energy change of this...

AQA · GCSE · Chemistry

Chemical changes

04.4 · 2 marks Completing a zinc ionic equation Complete the ionic equation for the reaction between zinc and copper sulfate solution. Include state symbols. 05.2 · 1 mark Ion mobility in solid electrolytes Solid calcium chloride cannot be electrolysed. Give one reason why. 05.3 · 1 mark Negative-electrode product in aqueous electrolysis Name the product formed at the negative electrode when aqueous calcium chloride solution is electrolysed. 05.4 · 1 mark Positive-electrode half equation What is the half equation for the reaction at the positive electrode when aqueous calcium chloride solution is electrolysed?... 05.5 · 3 marks Explaining copper chromate ion migration Copper chromate solution contains the ions Cu²⁺ and CrO₄²⁻. Explain the results shown in Figure 5. 07.4 · 1 mark Ion ratio in magnetite The most common oxides of iron are Fe₂O₃ and Fe₃O₄. What is the ratio of the numbers of ions in Fe₃O₄? Tick one box. 09.1 · 2 marks Defining a weak acid Acids can be either weak or strong. What is meant by ‘a weak acid’? 09.2 · 2 marks Effect of dilution on acid pH Explain what happens to the pH of an acid as the acid is diluted with water. 09.3 · 3 marks Preparing an alkali for titration A student does a titration to find the volume of acid needed to neutralise an alkali. The student fills a burette with the acid....

AQA · GCSE · Chemistry

Quantitative chemistry

04.5 · 3 marks Calculating a mean with uncertainty Calculate the mean highest temperature reached. Include the uncertainty in your answer. 07.3 · 1 mark Balancing iron and chlorine stoichiometry When iron reacts with chlorine, 0.12 mol of iron reacts with 0.18 mol of chlorine (Cl₂). Which is the correct equation for the... 07.5 · 3 marks Percentage iron by mass in magnetite Calculate the percentage (%) by mass of iron in Fe₃O₄. Relative atomic masses (Aᵣ): O = 16, Fe = 56. 07.6 · 5 marks Calculating carbon dioxide gas volume Fe₂O₃ reacts with carbon to produce carbon dioxide. Calculate the volume of carbon dioxide gas at room temperature and pressure... 09.4 · 2 marks Calculating hydrochloric acid titration volume The student titrated a solution containing 0.0045 moles of sodium hydroxide with 0.15 mol/dm³ hydrochloric acid. The equation...

AQA · GCSE · Chemistry

Bonding, structure, and the properties of matter

05.1 · 4 marks Forming calcium chloride ions Calcium and chlorine react to produce calcium chloride. Describe what happens to calcium atoms and chlorine atoms when the ionic... 07.2 · 3 marks Atomic layers in iron alloys Pure iron is too soft for many uses. Explain why mixing iron with other metals makes alloys which are harder than pure iron. 09.5 · 3 marks Electron shielding and calcium reactivity A calcium atom is larger than a magnesium atom. Explain why calcium reacts more vigorously than magnesium with hydrochloric acid...