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1 For more awesome GSE and level resources, visit us at Redox Question Paper Level Subject Exam oard Topic Sub-Topic Paper Type International Level hemistry IE Electrochemistry Redox Multiple hoice ooklet Question Paper Time llowed: Score: 5 minutes /4 Percentage: /00 Grade oundaries: * E U >85% 777.5% 70% 6.5% 57.5% 45% <45%

2 For more awesome GSE and level resources, visit us at Section For each question there are four possible answers,,,, and. hoose the one you consider to be correct. In oxygen difluoride, OF, fluorine has an oxidation number of. OF will react with sulfur dioxide according to the following equation. OF + SO SO + F What is oxidised and what is reduced in this reaction? hlorate(v) ions, l O, are produced in the redox reaction between chlorine and hot aqueous sodium hydroxide. Oxidation numbers can be used to help balance the equation for this reaction. What will be the values of coefficients v, x and y in the balanced equation? vl (g) + woh (aq) xl (aq) + yl O (aq) + zh O(l)

3 For more awesome GSE and level resources, visit us at In which reaction does an element have the largest change in oxidation number? + r O 7 + 6Fe + 4H + r + + 6Fe + + 7H O Ol l O + l + 5Fe + MnO 4 + 8H + 5Fe + + Mn + + 4H O + PbO + Sn + 4H + Sn 4+ + Pb + + H O 4 Redox reactions occur very frequently in the chemistry of Group VII. Which statement is correct? hlorine will oxidise bromide ions but not iodide ions. Fluorine is the weakest oxidising agent out of F, l, r and I. Iodide ions are the weakest reducing agent out of F, l, r and I. When chlorine reacts with water, chlorine is both oxidised and reduced. 5 In which reaction is the species in bold acting as an oxidising agent? a + O ao r O 7 + 8H + + SO r + + 4H O + SO 4 Mg + Fe + Mg + + Fe SO + H O + u + + l H SO 4 + H + + ul 6 When solid sodium iodide reacts with concentrated sulfuric acid, the products include NaHSO 4, H S, SO and S. In the formation of which product has the oxidation state of sulfur changed by a value of 8? H S NaHSO 4 S SO

4 For more awesome GSE and level resources, visit us at 7 In which reaction does hydrogen behave as an oxidising agent? H + l Hl H 4 + H H 6 N + H NH Na + H NaH 8 hlorine gas reacts with cold aqueous sodium hydroxide. It can also react with hot aqueous sodium hydroxide. What are the oxidation numbers of chlorine in the products of these reactions? 9 luminium carbide, l 4, reacts readily with aqueous sodium hydroxide. The two products of the reaction are Nal O and a hydrocarbon. Water molecules are also involved as reactants. What is the formula of the hydrocarbon? H 4 H 6 H 8 6 H 0 What is the ionic equation for the reaction between aqueous sodium carbonate and dilute nitric acid? HNO (aq) + O (aq) H O(l) + O (g) + NO (aq) H + (aq) + O (aq) O (g) + H O(l) HNO (aq) + Na O (aq) NaNO (aq) + O (g) + H O(l) HNO (aq) + O (aq) H O(l) + O (g) + NO (aq)

5 For more awesome GSE and level resources, visit us at Solutions containing chlorate(i) ions are used as household bleaches and disinfectants. These solutions decompose on heating as shown. l O l O + l Which oxidation state is shown by chlorine in each of these three ions? What happens when iodine solution is added to a solution of sodium bromide? reaction occurs without changes in oxidation state. romide ions are oxidised, iodine atoms are reduced. romide ions are reduced, iodine atoms are oxidised. No reaction occurs. What happens when bromine solution is added to a solution of sodium iodide? reaction occurs without changes in oxidation state. romine atoms are oxidised, iodide ions are reduced. romine atoms are reduced, iodide ions are oxidised. No reaction occurs.

6 For more awesome GSE and level resources, visit us at 4 In the redox reaction shown, how do the oxidation states of vanadium and sulfur change? VO + + SO V + + SO 4 5 The following half reactions occur when potassium iodate(v), KIO, in hydrochloric acid solution oxidises iodine to Il. IO + l + 6H + + 4e Il + H O I + 4l Il + e What is the ratio of IO to I in the balanced chemical equation for the overall reaction? : : : 4 : 6 In which reaction does a single nitrogen atom have the greatest change in oxidation number? 4NH + 5O 4NO + 6H O NO + H O HNO + NO NO + O NO 4NH + 6NO 5N + 6H O

7 For more awesome GSE and level resources, visit us at 7 Solid potassium halides react with concentrated sulfuric acid, according to the following equations. reaction reaction reaction Kl + H SO 4 K SO 4 + Hl Kr + H SO 4 K SO 4 + SO + r + H O 8KI + 5H SO 4 4K SO 4 + H S + 4I + 4H O What is the largest change in the oxidation number of sulfur in each of these reactions? 8 mmonium nitrate, NH 4 NO, can decompose explosively when heated. NH 4 NO N O + H O What are the changes in the oxidation numbers of the two nitrogen atoms in NH 4 NO when this reaction proceeds?, 4 +, +6 +4, 6 +4, cm sample of 0.0 mol dm Tl + NO required 0 cm of 0.0 mol dm acidified NH 4 VO to oxidise it to Tl + in solution. Vanadium is the only element reduced in this reaction. What is the oxidation number of the vanadium in the reduced form?

8 For more awesome GSE and level resources, visit us at 0 The oxide of titanium, TiO, is used as a whitener in toothpaste. It is obtained from the ore iron(ii) titanate, FeTiO. What is the change, if any, in the oxidation number (oxidation state) of titanium in the reaction FeTiO TiO? It is oxidised from + to +4. It is reduced from + to +. It is reduced from +6 to +4. There is no change in the oxidation number. In the treatment of domestic water supplies, chlorine is added to the water to form Hl O. The Hl O reacts further to give l O ions. l (aq) + H O(I) H + (aq) + l (aq) + Hl O(aq) Hl O(aq) + H O(I) H O + (aq) + l O (aq) oth Hl O and l O kill bacteria by oxidation. What is the overall change in oxidation number of chlorine when forming the l O ion from the aqueous chlorine? In which substance does nitrogen exhibit the highest oxidation state? NO N O N O 4 NaNO hlorine shows oxidation states ranging from to +7 in its compounds. What are the reagent(s) and conditions necessary for the oxidation of elemental chlorine into a compound containing chlorine in the +5 oxidation state? gno (aq) followed by NH (aq) at room temperature concentrated H SO 4 at room temperature cold dilute NaOH(aq) hot concentrated NaOH(aq)

9 For more awesome GSE and level resources, visit us at 4 In which reaction does an element undergo the largest change in oxidation state? l + OH Ol + l + H O l + 6OH l O + 5l + H O + r O 7 + 6Fe + 4H + r + + 6Fe + + 7H O MnO 4 + 4H + MnO + MnO 4 + H O 5 The reaction between KI and concentrated H SO 4 is a redox reaction. 5H SO 4 + 8KI 4K SO 4 + 4I + H S + 4H O What is the change in oxidation state of the element that is reduced? In flooded soils, like those used for rice cultivation, the oxygen content is low. In such soils, anaerobic bacteria cause the loss of nitrogen from the soil as shown in the following sequence. In which step is the change in oxidation number (oxidation state) of nitrogen different to the changes in the other steps? NO (aq) NO (aq) NO(g) N O(g) N (g) 7 Which compound contains two different elements with identical oxidation states? Hl O Mg(OH) Na SO 4 NH 4 l

10 For more awesome GSE and level resources, visit us at 8 student observed the reactions when sodium chloride and sodium iodide were each reacted separately with concentrated sulfuric acid and with concentrated phosphoric acid. The observations are recorded in the table. conc. H SO 4 conc. H PO 4 sodium chloride colourless acidic gas formed colourless acidic gas formed sodium iodide purple vapour formed colourless acidic gas formed Which deduction can be made from these observations? oncentrated phosphoric acid is a stronger oxidising agent than concentrated sulfuric acid. oncentrated phosphoric acid is a stronger oxidising agent than iodine. oncentrated sulfuric acid is a stronger oxidising agent than chlorine. oncentrated sulfuric acid is a stronger oxidising agent than iodine. 9 When chlorine and aqueous sodium hydroxide are heated together the following overall reaction occurs. l (aq) + 6NaOH(aq) 5Nal (aq) + Nal O (aq) + H O(l) What are the oxidation numbers for chlorine in each of the following species? 0 The following equations the letters W, X, Y and Z all represent whole numbers. When correctly balanced, which equation requires one of letters W, X, Y or Z to be 5? W H 7 OOH + XO YO + ZH O W 4 H 8 + XO YO + ZH O WH PO 4 + XNaOH YNa HPO 4 + ZH O WNH + XO YN + ZH O

11 For more awesome GSE and level resources, visit us at The amount of titanium dioxide in an ore can be determined by using the following reaction. TiO + 4rF TiF 4 + r + O Which element increases in oxidation number in this reaction? bromine fluorine oxygen titanium Sodium iodide reacts with concentrated sulfuric acid. The equation which represents one of the reactions that takes place is shown. 8NaI + 9H SO 4 8NaHSO 4 + 4I + H S + 4H O Which species has been oxidised in this reaction? H + I Na + SO 4 mmonium nitrate, NH 4 NO, can decompose explosively when heated. NH 4 NO N O + H O What are the changes in the oxidation numbers of the two nitrogen atoms in NH 4 NO when this reaction proceeds?, 4 +, +6 +4, 6 +4, 4 4 How does concentrated sulfuric acid behave when it reacts with sodium chloride? as an acid only as an acid and oxidising agent as an oxidising agent only as a reducing agent only

12 For more awesome GSE and level resources, visit us at Section For each of the questions in this section, one or more of the three numbered statements to may be correct. ecide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that you consider to be correct). The responses to should be selected on the basis of, and are correct and only are correct and only are correct only is correct 5 Which of these reactions are redox reactions? 6NO(g) + 4NH (g) 5N (g) + 6H O(g) SO (g) + O (g) SO (g) SO (g) + H O(g) H SO 4 (g) 6 When dilute acid is added to an aqueous solution containing nitrite ions, NO, a mixture of gases is produced. H + (aq) + NO (aq) H O(l) + NO(g) + NO (g) Which statements correctly describe the process? Some nitrogen atoms are oxidised and some nitrogen atoms are reduced. The H + (aq) ion is oxidised by NO (aq). The H + (aq) ion acts as a catalyst.

13 For more awesome GSE and level resources, visit us at 7 Which pairs of reagents will react together in a redox reaction? H HO + Fehling s reagent H 4 + r (aq) H 4 + l (g) 8 Which pairs of reagents will take part in a redox reaction? H OH + Tollens reagent H H HO + Fehling s reagent H H=H + r 9 Which pairs of reagents will take part in a redox reaction under suitable conditions? H (H ) 4 HO + Tollens reagent H (H ) 4 H + r H O(H ) 4 H + Fehling s reagent 40 Many crude oils contain H S. uring refining, by the laus process, the H S is converted into solid sulfur, which is then removed. reaction I reaction II H S(g) + O (g) H O(l) + SO (g) H S(g) + SO (g) H O(l) + S(s) Which statements about the laus process are correct? HS is oxidised in reaction I. SO oxidises H S in reaction II. Hydrogen is oxidised in reaction II.

14 For more awesome GSE and level resources, visit us at 4 In a solution that contains both r and l, a process takes place that produces ro ions. The process is represented by the following equations. equation r + H O Hr + HrO equation HrO + l l + ro + r + H + Which statements about these reactions are correct? hlorine is reduced in equation. romine is oxidised in both equation and equation. romine is reduced in both equation and equation. 4 Which pairs of reagents will react together in a redox reaction? H HO + Fehling s reagent H 4 + l H OH + Tollens reagent

Redox. Question Paper. Cambridge International Examinations Chemical Reactions. Score: /43. Percentage: /100

Redox. Question Paper. Cambridge International Examinations Chemical Reactions. Score: /43. Percentage: /100 Redox Question Paper Level Subject Exam oard Topic Sub-Topic ooklet O Level hemistry ambridge International Examinations hemical Reactions Redox Question Paper Time llowed: 52 minutes Score: /43 Percentage: