1. What is the sum of all coefficients when the following equation is balanced using the smallest possible whole numbers? D.

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Madeleine Chapman
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1 1. What is the sum of all coefficients when the following equation is balanced using the smallest possible whole numbers? A. 5 B. 7 C. 11 C 2 H 2 + O 2 CO 2 + H 2 O D g of NaNO 3 (M r = 85) is dissolved in water to prepare 0.20 dm 3 of solution. What is the concentration of the resulting solution in mol dm 3? A B. 0.1 C. 0.2 D How many molecules are present in a drop of ethanol, C 2 H 5 OH, of mass g? (L = mol 1 ) A B C D

2 4. Which sample has the greatest mass? A. 1 mol of SO 2 B. 2 mol of N 2 O C. 2 mol of Ar D. 4 mol of NH 3 5. The relative molecular mass of a gas is 56 and its empirical formula is CH 2. What is the molecular formula of the gas? A. CH 2 B. C 2 H 4 C. C 3 H 6 D. C 4 H 8 6. Ethanol is used as a component in fuel for some vehicles. One fuel mixture contains 10 % by mass of ethanol in unleaded petrol (gasoline). This mixture is often referred to as Gasohol E10. (a) Assume that the other 90 % by mass of Gasohol E10 is octane kg of this fuel mixture was burned. CH 3 CH 2 OH(l) + 3O 2 (g) 2CO 2 (g) + 3H 2 O(l) H O = 1367 kj mol 1 1 C 8 H 18 (l) + 12 O 2 (g) 8CO 2 (g) + 9H 2 O(l) 2 H O = 5470 kj mol 1 (i) Calculate the mass, in g, of ethanol and octane in 1.00 kg of the fuel mixture.

3 (ii) Calculate the amount, in mol, of ethanol and octane in 1.00 kg of the fuel mixture. (iii) Calculate the total amount of energy, in kj, released when 1.00 kg of the fuel mixture is completely burned. (3) (b) If the fuel blend was vaporized before combustion, predict whether the amount of energy released would be greater, less or the same. Explain your answer. (Total 7 marks)

4 7. What mass, in g, of hydrogen is formed when 3 mol of aluminium react with excess hydrochloric acid according to the following equation? A. 3.0 B. 4.5 C Al(s) + 6HCl(aq) 2AlCl 3 (aq) + 3H 2 (g) D What is the total number of hydrogen atoms in 1.0 mol of benzamide, C 6 H 5 CONH 2? A. 7 B C D What is the sum of the coefficients for the equation when balanced using the smallest possible whole numbers? A. 5 B. 6 C. 7 N 2 H 4 (g) + O 2 (g) NO 2 (g) + H 2 O(g) D. 8

5 10. Chloroethene, C 2 H 3 Cl, reacts with oxygen according to the equation below. 2C 2 H 3 Cl(g) + 5O 2 (g) 4CO 2 (g) + 2H 2 O(g) + 2HCl(g) What is the amount, in mol, of H 2 O produced when 10.0 mol of C 2 H 3 Cl and 10.0 mol of O 2 are mixed together, and the above reaction goes to completion? A B C D A fixed mass of gas has a certain volume at a temperature of 50 C. What temperature is required to double its volume while keeping the pressure constant? A. 100 K B. 323 K C. 373 K D. 646 K 12. What is the concentration of NaCl, in mol dm 3, when 10.0 cm 3 of mol dm 3 NaCl solution is added to 30.0 cm 3 of mol dm 3 NaCl solution? A B C D

6 13. Which amount of the following compounds contains the least number of ions? A. 2 mol of NaOH B. 1 mol of NH 4 Cl C. 2 mol of CaCl 2 D. 1 mol of Al 2 O What is the approximate molar mass, in g mol 1, of MgSO 4 7H 2 O? A. 120 B. 130 C. 138 D Which is both an empirical and a molecular formula? A. C 5 H 12 B. C 5 H 10 C. C 4 H 8 D. C 4 H 10

16. 12 molecules of hydrogen gas, H 2 (g), and 5 molecules of oxygen gas, O 2 (g), were mixed

7 molecules of hydrogen gas, H 2 (g), and 5 molecules of oxygen gas, O 2 (g), were mixed together under conditions which allowed the reaction to go to completion, according to the following equation. 2H 2 (g) + O 2 (g) 2H 2 O(g) The following diagram represents the mixture of reactants. Which diagram represents the reaction mixture when the reaction was complete? A. B. C.

D. 17. Brass is a copper containing alloy with many uses. An analysis is carried out to determine the percentage of copper present in three identical samples of brass.

8 D. 17. Brass is a copper containing alloy with many uses. An analysis is carried out to determine the percentage of copper present in three identical samples of brass. The reactions involved in this analysis are shown below. Step 1: Cu(s) + 2HNO 3 (aq) + 2H + (aq) Cu 2+ (aq) + 2NO 2 (g) + 2H 2 O(l) Step 2: 4I (aq) + 2Cu 2+ (aq) 2CuI(s) + I 2 (aq) Step 3: I 2 (aq) + 2S 2 O 3 2 (aq) 2I (aq) + S 4 O 6 2 (aq) (a) (i) Deduce the change in the oxidation numbers of copper and nitrogen in step 1. Copper: Nitrogen: (ii) Identify the oxidizing agent in step 1.

9 (b) A student carried out this experiment three times, with three identical small brass nails, and obtained the following results. Mass of brass = g ± g Titre Initial volume of mol dm 3 S 2 O 2 3 (± 0.05 cm 3 ) Final volume of mol dm 3 S 2 O 2 3 (± 0.05 cm 3 ) Volume added of mol dm 3 S 2 O 2 3 (± 0.10 cm 3 ) Average volume added of mol dm 3 S 2 O 3 2 (± 0.10 cm 3 ) (i) Calculate the average amount, in mol, of S 2 O 2 3 added in step 3. (ii) Calculate the amount, in mol, of copper present in the brass. (iii) Calculate the mass of copper in the brass. (iv) Calculate the percentage by mass of copper in the brass.

10 (v) The manufacturers claim that the sample of brass contains 44.2 % copper by mass. Determine the percentage error in the result. (c) With reference to its metallic structure, describe how brass conducts electricity. (Total 10 marks) 18. What is the coefficient of Fe 3 O 4 when the following equation is balanced using the lowest whole numbers? A. 2 B. 3 C. 4 Al(s) + Fe 3 O 4 (s) Al 2 O 3 (s) + Fe(s) D What is the mass, in g, of one molecule of ethane, C 2 H 6? A B C. 30 D

11 20. Which molecular formula is also an empirical formula? A. PCl 3 B. C 2 H 4 C. H 2 O 2 D. C 6 H 12 O Which of the following is consistent with Avogadro s law? P A. = constant (V, n constant) T V B. = constant (P, n constant) T C. Vn = constant (P, T constant) V D. = constant (P, T constant) n 22. The percentage by mass of calcium carbonate in eggshell was determined by adding excess hydrochloric acid to ensure that all the calcium carbonate had reacted. The excess acid left was then titrated with aqueous sodium hydroxide. (a) A student added cm 3 of mol dm 3 HCl to g of eggshell. Calculate the amount, in mol, of HCl added.

12 (b) The excess acid requires cm 3 of mol dm 3 NaOH for neutralization. Calculate the amount, in mol, of acid that is in excess. (c) Determine the amount, in mol, of HCl that reacted with the calcium carbonate in the eggshell. (d) State the equation for the reaction of HCl with the calcium carbonate in the eggshell. (e) Determine the amount, in mol, of calcium carbonate in the sample of the eggshell.

13 (f) Calculate the mass and the percentage by mass of calcium carbonate in the eggshell sample. (3) (g) Deduce one assumption made in arriving at the percentage of calcium carbonate in the eggshell sample. (Total 11 marks) mol of aluminium reacts with oxygen to form aluminium oxide. What is the amount of oxygen, in mol, needed for complete reaction? A. 1.5 B. 3.0 C Al(s) + 3O 2 (g) 2Al 2 O 3 (s) D. 6.0

14 24. What is the total number of nitrogen atoms in two mol of NH 4 NO 3? A. 4 B C D On analysis, a compound with molar mass 60 g mol 1 was found to contain 12 g of carbon, 2 g of hydrogen and 16 g of oxygen. What is the molecular formula of the compound? A. CH 2 O B. CH 4 O C. C 2 H 4 O D. C 2 H 4 O Equal masses of the metals Na, Mg, Ca and Ag are added to separate samples of excess HCl(aq). Which metal produces the greatest total volume of H 2 (g)? A. Na B. Mg C. Ca D. Ag

15 27. The graph below represents the relationship between two variables in a fixed amount of gas. Which variables could be represented by each axis? x-axis y-axis A. pressure temperature B. volume temperature C. pressure volume D. temperature volume g of NH 3 are dissolved in H 2 O to prepare a 500 cm 3 solution. Which statements are correct? I. NH 3 is the solute and H 2 O is the solution II. The concentration of the solution is 17 g dm 3 III. [NH 3 ] = 1.0 mol dm 3 A. I and II only B. I and III only C. II and III only D. I, II and III

16 29. Consider the following sequence of reactions. reaction 1 reaction 2 reaction 3 RCH 3 RCH 2 Br RCH 2 OH RCOOH RCH 3 is an unknown alkane in which R represents an alkyl group. (a) The alkane contains 81.7 % by mass of carbon. Determine its empirical formula, showing your working. (3) (b) Equal volumes of carbon dioxide and the unknown alkane are found to have the same mass, measured to an accuracy of two significant figures, at the same temperature and pressure. Deduce the molecular formula of the alkane. (c) (i) State the reagent and conditions needed for reaction 1. (ii) State the reagent(s) and conditions needed for reaction 3. (d) Reaction 1 involves a free-radical mechanism. Describe the stepwise mechanism, by giving equations to represent the initiation, propagation and termination steps. (4) (e) The mechanism in reaction 2 is described as S N 2. (i) State the meaning of each of the symbols in S N 2. (ii) Explain the mechanism of this reaction using curly arrows to show the movement of electron pairs, and draw the structure of the transition state. (3) (Total 16 marks)

17 cm 3 of water is added to a solution of 200 cm 3 of 0.5 mol dm 3 sodium chloride. What is the concentration of sodium chloride in the new solution? A mol dm 3 B. 0.1 mol dm 3 C. 0.2 mol dm 3 D. 0.3 mol dm The molar mass of a compound is approximately 56 g mol 1. Which formula is possible for this compound? A. NaNO 3 B. AgOH C. MgO D. KOH 32. Which compound has the empirical formula with the largest mass? A. C 2 H 6 B. C 2 H 4 C. C 2 H 2 D. C 3 H 6

18 33. What is the coefficient for O 2 (g) when the equation for the combustion of 1 mole of pentane is balanced? A. 5 B. 6 C. 8 C 5 H 12 (g) + _O 2 (g) _CO 2 (g) + _H 2 O(g) D What is the maximum mass, in g, of magnesium oxide that can be obtained from the reaction of oxygen with 2.4 g of magnesium? A. 2.4 B. 3.0 C. 4.0 D dm 3 of carbon monoxide, CO(g), and 2 dm 3 of oxygen, O 2 (g), at the same temperature and pressure are mixed together. Assuming complete reaction according to the equation given, what is the maximum volume of carbon dioxide, CO 2 (g), in dm 3, that can be formed? 2CO(g) + O 2 (g) 2CO 2 A. 3 B. 4 C. 5 D. 7

19 36. Which statement about solutions is correct? A. When vitamin D dissolves in fat, vitamin D is the solvent and fat is the solute. B. In a solution of NaCl in water, NaCl is the solute and water is the solvent. C. An aqueous solution consists of water dissolved in a solute. D. The concentration of a solution is the amount of solvent dissolved in 1 dm 3 of solution. 37. Biodiesel makes use of plants ability to fix atmospheric carbon by photosynthesis. Many companies and individuals are now using biodiesel as a fuel in order to reduce their carbon footprint. Biodiesel can be synthesized from vegetable oil according to the following reaction. (a) Identify the organic functional group present in both vegetable oil and biodiesel.

20 (b) For part of her extended essay investigation into the efficiency of the process, a student reacted a pure sample of a vegetable oil (where R = C 17 H 33 ) with methanol. The raw data recorded for the reaction is below. Mass of oil = g Mass of methanol = g Mass of sodium hydroxide = 3.5 g Mass of biodiesel produced = g The relative molecular mass of the oil used by the student is Calculate the amount (in moles) of the oil and the methanol used, and hence the amount (in moles) of excess methanol. (3) (c) The reversible arrows in the equation indicate that the production of biodiesel is an equilibrium process. (i) State what is meant by the term dynamic equilibrium. (ii) Using the abbreviations [vegetable oil], [methanol], [glycerol] and [biodiesel] deduce the equilibrium constant expression (K c ) for this reaction. (iii) Suggest a reason why excess methanol is used in this process.

21 (iv) State and explain the effect that the addition of the sodium hydroxide catalyst will have on the position of equilibrium. (d) The reactants had to be stirred vigorously because they formed two distinct layers in the reaction vessel. Explain why they form two distinct layers and why stirring increases the rate of reaction. (e) Calculate the percentage yield of biodiesel obtained in this process. (f) When biodiesel is combusted it produces carbon dioxide. Explain why the use of biodiesel as a fuel does not significantly contribute to global warming. (Total 14 marks)

22 38. The percentage of iron(ii) ions, Fe 2+, in a vitamin tablet can be estimated by dissolving the tablet in dilute sulfuric acid and titrating with standard potassium manganate(vii) solution, KMnO 4 (aq). During the process iron(ii) is oxidized to iron(iii) and the manganate(vii) ion is reduced to the manganese(ii) ion, Mn 2+ (aq). It was found that one tablet with a mass of 1.43 g required 11.6 cm 3 of mol dm 3 KMnO 4 (aq) to reach the end-point. (a) (i) State the half-equation for the oxidation of the iron(ii) ions. (ii) State the half-equation for the reduction of the MnO 4 ions in acidic solution. (iii) Deduce the overall redox equation for the reaction. (b) (i) Calculate the amount, in moles, of MnO 4 ions present in 11.6 cm 3 of mol dm 3 KMnO 4 (aq). (ii) Calculate the amount, in moles, of Fe 2+ ions present in the vitamin tablet.

23 (iii) Determine the percentage by mass of Fe 2+ ions present in the vitamin tablet. (Total 7 marks) 39. What is the number of oxygen atoms in one mole of CuSO 4 5H 2 O? A. 5 B. 9 C D Which sample has the greatest mass? A molecules of hydrogen B. 5.0 mol of neon atoms C atoms of silver D g of iron

24 41. What volume of sulfur trioxide, in cm 3, can be prepared using 40 cm 3 sulfur dioxide and 20 cm 3 oxygen gas by the following reaction? Assume all volumes are measured at the same temperature and pressure. A. 20 B. 40 C. 60 2SO 2 (g) + O 2 (g) 2SO 3 (g) D Which sample of nitrogen gas, N 2, contains the greatest number of nitrogen molecules? A. 1.4 g N 2 B. 1.4 dm 3 of N 2 at Pa and 273 K C N 2 molecules D. 1.4 mol N Aspirin, one of the most widely used drugs in the world, can be prepared according to the equation given below.

25 (a) State the names of the three organic functional groups in aspirin. (3) (b) A student reacted some salicylic acid with excess ethanoic anhydride. Impure solid aspirin was obtained by filtering the reaction mixture. Pure aspirin was obtained by recrystallization. The following table shows the data recorded by the student. Mass of salicylic acid used Mass of pure aspirin obtained 3.15 ± 0.02 g 2.50 ± 0.02 g (i) Determine the amount, in mol, of salicylic acid, C 6 H 4 (OH)COOH, used. (ii) Calculate the theoretical yield, in g, of aspirin, C 6 H 4 (OCOCH 3 )COOH. (iii) Determine the percentage yield of pure aspirin.

26 (iv) State the number of significant figures associated with the mass of pure aspirin obtained, and calculate the percentage uncertainty associated with this mass. (v) Another student repeated the experiment and obtained an experimental yield of 150 %. The teacher checked the calculations and found no errors. Comment on the result. (Total 11 marks) 44. Smog is common in cities throughout the world. One component of smog is PAN (peroxyacylnitrate) which consists of 20.2 % C, 11.4 % N, 65.9 % O and 2.50 % H by mass. Determine the empirical formula of PAN, showing your working (Total 3 marks)

27 45. Which non-metal forms an oxide XO 2 with a relative molecular mass of 60? A. C B. N C. Si D. S 46. How many oxygen atoms are there in 0.20 mol of ethanoic acid, CH 3 COOH? A B C D mol of a hydrocarbon with an empirical formula of CH 2 has a mass of 280 g. What is the molecular formula of this compound? A. C 2 H 4 B. C 3 H 6 C. C 4 H 8 D. C 5 H 10

28 48. What will be the concentration of sulfate ions in mol dm 3 when 0.20 mol of KAl(SO 4 ) 2 is dissolved in water to give 100 cm 3 of aqueous solution? A. 0.2 B. 1.0 C. 2.0 D The volume of an ideal gas at 27.0 C is increased from 3.00 dm 3 to 6.00 dm 3. At what temperature, in C, will the gas have the original pressure? A B C. 327 D The data below is from an experiment used to determine the percentage of iron present in a sample of iron ore. This sample was dissolved in acid and all of the iron was converted to Fe 2+. The resulting solution was titrated with a standard solution of potassium manganate(vii), KMnO 4. This procedure was carried out three times. In acidic solution, MnO 4 reacts with Fe 2+ ions to form Mn 2+ and Fe 3+ and the end point is indicated by a slight pink colour. titre initial burette reading / cm Final burette reading / cm Mass of iron ore / g concentration of KMnO 4 solution / mol dm

29 (a) Deduce the balanced redox equation for this reaction in acidic solution. (b) Identify the reducing agent in the reaction. (c) Calculate the amount, in moles, of MnO 4 used in the titration. (d) Calculate the amount, in moles, of Fe present in the g sample of iron ore.

30 (e) Determine the percentage by mass of Fe present in the g sample of iron ore. (Total 9 marks) 51. Which coefficients would balance this equation? MnO 2 + HCl MnCl 2 + Cl 2 + H 2 O MnO 2 HCl MnCl 2 Cl 2 H 2 O A B C D What volume of carbon dioxide, in dm 3 under standard conditions, is formed when 7.00 g of ethene (C 2 H 4, M r = 28.1) undergoes complete combustion? A. B. C. D

31 53. How many hydrogen atoms are in one mole of ethanol, C 2 H 5 OH? A B C D What is the coefficient for H 2 SO 4 (aq) when the following equation is balanced, using the smallest possible integers? A. 1 B. 3 C. 4 Mg 3 N 2 (s) + H 2 SO 4 (aq) MgSO 4 (aq) + (NH 4 ) 2 SO 4 (aq) D Air bags in cars inflate when sodium azide decomposes to form sodium and nitrogen: 2NaN 3 (s) 2Na(s) + 3N 2 (g) Calculate the amount, in moles, of nitrogen gas produced by the decomposition of 2.52 mol of NaN 3 (s). A B C D. 7.56

32 56. What volume, in cm 3, of mol dm 3 HCl(aq) is required to neutralize 25.0 cm 3 of mol dm 3 Ba(OH) 2 (aq)? A B C D mol of aluminium hydroxide is mixed with mol of sulfuric acid, and the following reaction occurs: 2Al(OH) 3 (s) + 3H 2 SO 4 (aq) Al 2 (SO 4 ) 3 (aq) + 6H 2 O(l) (a) Determine the limiting reactant (b) Calculate the mass of Al 2 (SO 4 ) 3 produced

33 (c) Determine the amount (in mol) of excess reactant that remains (d) Define a Brønsted-Lowry acid and a Lewis base. Brønsted-Lowry acid... Lewis base... (e) H 2 SO 4 (aq) is a strong acid. State the name and the formula of any weak acid (Total 8 marks) 58. A toxic gas, A, consists of 53.8 % nitrogen and 46.2 % carbon by mass. At 273 K and Pa, g of A occupies 462 cm 3. Determine the empirical formula of A. Calculate the molar mass of the compound and determine its molecular structure. (Total 3 marks)

American International School of Johannesburg. Quantitative Revision Questions II

American International School of Johannesburg Quantitative Revision Questions II 1. A toxic gas, A, consists of 53.8 % nitrogen and 46.2 % carbon by mass. At 273 K and 1.01 10 5 Pa, 1.048 g of A occupies