Year 10 Chemistry Practice questions Topics 1 Group 1 2 Group 7 3 Reactivity series 4 Air and Water 5 Rates of reaction 6 Electrolysis 7 Acids, Alkali and Salts
Objective: Evaluate group 1 & 7 reactivity using experimental techniques MA Questions Q1 Lithium, potassium and caesium are three metals in Group 1 of the Periodic Table (a) A small piece of each metal is placed on water in separate large troughs Complete the table by giving the correct metal, lithium, potassium or caesium, for each description (b) (i) Give the name and formula of the gas formed when potassium reacts with water name formula (ii) Give the name and formula of the compound formed when lithium reacts with water name formula (iii) Describe how you could show that an alkaline solution is formed when caesium reacts with water (Total for question = 8 marks)
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Objective: Explain results using scientific knowledge and understanding HA Questions Q1 This question is about elements in Group 7 of the Periodic Table (a) Complete the table to show the physical state at room temperature of fluorine and astatine, and the colour of liquid bromine (b) Chlorine reacts with hydrogen to form hydrogen chloride A piece of magnesium ribbon is added to hydrogen chloride in three separate experiments under different conditions The table below shows the observations made under these different conditions
(i) Write the formulae of two ions formed in the solution produced in experiment 2 Positive ion Negative ion (ii) Identify the gas formed in experiment 2 and give a test for it gas test (iii) Silver nitrate solution and dilute nitric acid are added to the solution produced in experiment 2 State what is observed and name the substance responsible for this observation Explain why dilute nitric acid is added (3) observation substance responsible explanation (iv) Explain why there is no reaction in experiment 3 (1) (Total for question = 10 marks)
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Objective: Identify rust conditions and explain methods of rust prevention HA Questions Q1 This question is about ways of preventing iron nails from rusting (a) This experiment is set up with three iron nails (i) What is the name of the main compound in rust? (1) (ii) Why does the nail in tube 1 not rust? (1) (iii) What is the purpose of the layer of oil in tube 2? (1) (b) Zinc can be used to coat iron nails to prevent them from rusting (i) What is the name of this process? (1)
(ii) If the layer of zinc on the nail is scratched, sacrificial protection prevents the iron from rusting Explain, with the help of two ionic half-equations, how this type of sacrificial protection works Use symbols from the box in your equations You may use each symbol once, more than once or not at all (4) (c) Electroplating is another method of rust prevention This apparatus can be used to electroplate an iron nail (i) Equation 1 shows the reaction at the copper rod Equation 1 Cu Cu 2+ + 2e Name this type of reaction, giving a reason for your answer type of reaction reason
(ii) Equation 2 shows the reaction at the iron nail Equation 2 Cu 2+ + 2e Cu Use equations 1 and 2 to explain why the colour of the copper(ii) sulfate solution does not change during the experiment (Total for question = 12 marks)
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Air and Water (Notes) 1 a) State why carbon monoxide is poisonous LA (1) MS Carbon monoxide is a poisonous gas that prevents hemoglobin in the blood from absorbing oxygen b) Describe a simple chemical test, and its result, for carbon dioxide LA Test Result Anions and Cations 1 Ammonium chloride contains oppositely charged ions (a) State the formula of each ion Positive ion Negative ion (b) (i) Describe a chemical test to show that a substance contains ammonium ions (3)
(ii) Describe a chemical test to show that a substance contains chloride ions HA (3)
Questi o n numbe r Answer Notes Marks a M1 NH 4 + Award 1 if wrong way around 1 b M2 Cl - Penalise missing charges both times 1 i M1 (add) sodium hydroxide/naoh (solution) (and warm) M2 test (gas / ammonia) with (damp red) litmus (paper) OR test with hydrogen chloride / conc HCl M3 (litmus paper) turns blue OR white smoke/solid/powder Accept any identified Group 1 or Group 2 hydroxide If no reagent added, max 1 mark for correct test AND result even if dipped into solution If just hydroxide or OH - ions, do not award M1 but continue marking If any other incorrect reagent added, then 0/3 Accept use of universal indicator Accept holding litmus above tube etc Reject blue litmus for M2 and M3 Do not penalise ammonium instead of ammonia in M2 Do not allow (dilute) hydrochloric acid Do not award M3 if litmus dipped into solution (even if only implied) 1 1 1 (add) silver nitrate/agno 3 (solution) If missing or incorrect reagent, 0/3 1 ii M1 M2 (dilute) nitric acid M3 white precipitate / solid / suspension Do not accept any other acid or just acidified If acid missing or wrong, M3 can still be awarded If bleaching litmus paper mentioned, only M1 can be awarded 1 1
Objective: Analyse the effects of temperature and catalysts on the rate of reaction based on collision theory Analyse plotted curves Questions Q1 A student measured the temperature change when 05 g of magnesium powder was added to 50 cm 3 of copper(ii) sulfate solution She repeated the experiment using 10 g, 15 g and 20 g of magnesium powder The diagrams of the thermometer show the highest temperature, in C, reached in each of the experiments (a) Use the thermometer readings to complete the table of results
(b) A second student carried out the experiment The table shows his results (i) Plot the points on the grid Draw a straight line through the first three points and another straight line through the last two points Make sure that the two lines cross (3)
(ii) Use your graph to find the mass of magnesium required to produce a temperature rise of 3 C (1) (c) Suggest why the last three temperature rises were the same (1) (d) State and explain the effect on the temperature rises if the student were to repeat the experiment using the same masses of zinc powder instead of magnesium powder Do not refer to the difference in reactivity of the two metals [relative atomic masses: Mg = 24; Zn = 65] (Total for Question = 9 marks)
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Objective: Analyze the effects of concentration on rates of reaction etc HA Questions Q1 Some students investigated the rate of reaction between sodium thiosulfate solution and hydrochloric acid The equation for the reaction is Na 2S 2O 3(aq) + 2HCl(aq) 2NaCl(aq) + H 2O(l) + S(s) + SO 2(g) The precipitate of sulfur makes the reaction mixture go cloudy The students used this method Place a mixture of sodium thiosulfate solution and water in a conical flask Add some dilute hydrochloric acid, swirl the mixture and start a timer Place the flask over a black cross marked on a piece of paper Record the time taken for the cross to disappear when viewed from abovethe students used 10 cm 3 of dilute hydrochloric acid in each experiment They carried out all the experiments at the same temperature They used different volumes of sodium thiosulfate solution and water in each experiment They were told to keep the total volume of sodium thiosulfate solution and water constant The table shows their results (a) Explain why the results of student 7 should not be used (1)
(b) Plot the results of the six other students on the grid below Draw a curve of best fit through the points (3) (c) The students used this equation to calculate the rate of each reaction in their investigation Calculate the rate of reaction for student 1's experiment Give your answer to one decimal place Rate =
(d) Another group of students used the same method but with different solutions of sodium thiosulfate and hydrochloric acid They calculated the rate of reaction for each experiment they did Their results are shown on the following graph (i) Describe the relationship between rate and concentration as shown by the graph (ii) Explain why increasing the concentration has this effect on the rate (3) (Total for Question = 11 marks)
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Electrolysis of Lead Bromide An experiment was carried out by a student to investigate the effect of electricity on molten lead (II) iodide (PbI 2) Below is an extract from the student s notebook a Define electrolysis? L1 [1] b Write the half equation for the reaction at the positive electrode? Use your equation to explain the student s observation at the anode L2, L3 The half equation at the Anode: [1] Explanation: [1] c Write the half equation for the reaction at the Cathode? L2 [1] d What type of reaction takes place at the Cathode? L1 [1] Mark scheme:
a Electrolysis is breaking down a compound using electricity 1 mark response for writing these key words in the definition; (breaking) and (electricity) b The half equation at the anode: 2I - - 2e I 2 1 mark for the correct equation At the anode purple iodine vapour is formed at the anode When iodine reaches the top of the tube, it sublimes into black solid crystals 1 mark for explaining any of the observations mentioned in the extract c The half equation at the cathode: Pb 2+ + 2e Pb 1 mark for the correct chemical equation d Reduction reaction 1 mark response
Objective: Preparation of salts using word and symbol equation HA Questions Q1 Lead(II) sulfate, PbSO 4, is an insoluble salt It can be made as a precipitate from a solution of lead(ii) nitrate, Pb(NO 3) 2 (a) (i) Identify a substance that could be added to lead(ii) nitrate solution to form a precipitate of lead(ii) sulfate (1) (ii) Write a chemical equation for the reaction between lead(ii) nitrate and the substance you identified in (a)(i) (iii) Outline how you would produce a pure, dry sample of lead(ii) sulfate from the reaction mixture in (a)(ii) (3) (b) A solution of lead(ii) nitrate can be made by reacting solid lead(ii) carbonate with dilute nitric acid The equation for this reaction is: PbCO 3(s) + 2HNO 3(aq) Pb(NO 3) 2(aq) + CO 2(g) + H 2O(l) State two observations you would make when dilute nitric acid is added to solid lead(ii) carbonate (Total for Question = 8 marks)
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Objective: Apply the preparation of explained salts MA Questions Q1 Several methods are used to prepare salts The method chosen depends on whether the salt is soluble or insoluble in water (a) An insoluble salt is prepared by mixing solutions of silver nitrate and sodium chloride (i) State the name of the insoluble salt formed (1) (ii) Write a chemical equation for the reaction occurring (b) The chemical equation for the preparation of the insoluble salt lead(ii) sulfate is shown below Complete the equation by adding state symbols (1) (c) A soluble salt is prepared from solutions of an acid and an alkali (i) Identify the acid and the alkali used to prepare sodium nitrate Acid Alkali (ii) The diagrams show the readings on a burette before and after a student added an alkali to an acid during a titration
Use these diagrams to complete the table below, entering all values to the nearest 005 cm 3 (3) (d) A second student also did the titration and recorded these results: The volumes of alkali added during these titrations are not all the same The average (mean) volume of alkali should be calculated using only concordant results Concordant results are those volumes that differ from each other by 020 cm 3 or less (i) Identify the concordant results by placing ticks in the table as shown (ii) Use your ticked results to calculate the average (mean) volume of alkali added (1)
Average (mean) volume = cm 3 (e) A student mixed together the acid and alkali to form sodium nitrate solution She used the volumes needed for complete reaction found in the titration She heated this solution in an evaporating basin to remove some of the water After cooling the concentrated solution, crystals of sodium nitrate formed What steps should she now take to obtain dry crystals of sodium nitrate? (Total for question = 17 marks)
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