SECTION A. 1 In which order do the electrons fill the orbitals of an atom? 1s 2s 2p 3s 3p 4s 4p 3d. 1s 2s 2p 3s 3d 3p 4s 4p. 1s 2s 2p 3s 3p 3d 4s 4p

Transcription

1 S hemistry Unit 1 SETION nswer LL the questions in this section. You should aim to spend no more than 20 minutes on this section. For each question, select one answer from to D and put a cross in the box. If you change your mind, put a line through the box and then mark your new answer with a cross. 1 In which order do the electrons fill the orbitals of an atom? 1s 2s 2p 3s 3p 4s 4p 3d 1s 2s 2p 3s 3d 3p 4s 4p 1s 2s 2p 3s 3p 3d 4s 4p D 1s 2s 2p 3s 3p 4s 3d 4p (Total for Question 1 = 1 mark) 2 Ions are separated in the mass spectrometer by D a vacuum pump. a magnetic field. an ionization chamber. electron bombardment. (Total for Question 2 = 1 mark) 3 Which of the following contains one mole of neutrons? 1 g of 1 1H 1 g of g of 24 12Mg D 2 g of 22 10Ne (Total for Question 3 = 1 mark) Page 1 of 23

2 S hemistry Unit 1 4 Solutions of barium chloride and silver nitrate are mixed together. The reaction that takes place is an example of D displacement. neutralization. oxidation. precipitation. (Total for Question 4 = 1 mark) 5 The vogadro constant is numerically equal to the number of ions in 1 mol of sodium chloride, Nal atoms in 1 mol of hydrogen gas, H 2 electrons in 1 mol of helium gas, He D molecules in 1 mol of oxygen gas, O 2 (Total for Question 5 = 1 mark) 6 10 g of magnesium is added to 1 dm 3 of 1 mol dm 3 copper(ii) sulfate solution and the mixture is stirred until no further reaction occurs. Which of the following is a result of this reaction? D The resulting solution is colourless. 10 g of copper is displaced g of copper is displaced. ll the magnesium reacts. (Total for Question 6 = 1 mark) Page 2 of 23

3 S hemistry Unit 1 7 Which of the following gas samples has the same volume as 7.0 g of carbon monoxide? ll volumes are measured at the same temperature and pressure. 1.0 g of hydrogen D 3.5 g of nitrogen 10.0 g of argon 35.5 g of chlorine (Total for Question 7 = 1 mark) 8 Which of the following aqueous solutions contains the greatest number of negative ions? D 500 cm 3 of 0.10 mol dm 3 Na 2 SO 4 (aq) 250 cm 3 of 0.12 mol dm 3 al 2 (aq) 250 cm 3 of 0.15 mol dm 3 KI(aq) 500 cm 3 of 0.10 mol dm 3 Zn(NO 3 ) 2 (aq) (Total for Question 8 = 1 mark) 9 In an experiment carried out at 200 o and 1 atm pressure, 20 cm 3 of ammonia gas reacted with an excess of heated copper(ii) oxide. 3uO(s) + 2NH 3 (g) 3u(s) + 3H 2 O(g) + N 2 (g) If all measurements were made at 200 o and 1 atm pressure, what would be the total volume, in cm 3, of gaseous products? D 40 (Total for Question 9 = 1 mark) Page 3 of 23

4 S hemistry Unit 1 10 mmonia is manufactured from hydrogen and nitrogen in the Haber process. 3H 2 (g) + N 2 (g) 2NH 3 (g) If 60 tonnes of hydrogen produces 80 tonnes of ammonia, what is the percentage yield in the reaction? % % % D % (Total for Question 10 = 1 mark) 11 Which of the following compounds has the greatest ionic character? aesium fluoride aesium iodide Potassium fluoride D Potassium iodide (Total for Question 11 = 1 mark) 12 Which species has a dative covalent bond? H 3 O + H 2 O OH D O 2 (Total for Question 12 = 1 mark) Page 4 of 23

5 S hemistry Unit 1 13 The atomic radius of potassium is larger than that of sodium because potassium has D a larger nuclear charge. a larger nucleus. more occupied electron shells. a smaller first ionization energy. (Total for Question 13 = 1 mark) 14 onsider the following data. S(s) + H 2 (g) H 2 S(g) H = a H 2 (g) + ½O 2 (g) H 2 O(l) H = b S(s) + O 2 (g) SO 2 (g) H = c H 2 S(g) + 1½O 2 (g) H 2 O(l) + SO 2 (g) H = d What is the relationship between a, b, c and d? a = b + c d a = d b c a = b c d D a = d + c b (Total for Question 14 = 1 mark) Page 5 of 23

6 S hemistry Unit 1 15 In which of the following does X represent the mean bond enthalpy for the O H bond in water? H 2 O(g) O(g) + H 2 (g) H = 2X H 2 O(g) O(g) + 2H(g) H = 2X H 2 O(g) O(g) + H 2 (g) H = X D H 2 O(g) O(g) + 2H(g) H = X (Total for Question 15 = 1 mark) 16 Which of the following is a step in the propagation stage of the chlorination of methane? l 2 l. + l. H 3. + l. H 3 l H 3. + l 2 H 3 l + l. D H 4 + l. H 3 l + H. (Total for Question 16 = 1 mark) 17 molecule of Z has the following structure: H H H H N H Molecule of Z What are the total numbers of -bonds and -bonds in a molecule of Z? Number of -bonds Number of -bonds D 14 6 (Total for Question 17 = 1 mark) Page 6 of 23

7 S hemistry Unit 1 18 Which is the structure of Z-1,2-dibromoprop-1-ene? D r H H r H r r H H 3 r H 2 r H H 3 r H 2 r H (Total for Question 18 = 1 mark) Page 7 of 23

8 S hemistry Unit 1 19 The skeletal formula of 3-methylcyclobut-1-ene is shown below. What is the skeletal formula of 1-ethyl-3-methylcyclopent-1-ene? D (Total for Question 19 = 1 mark) Page 8 of 23

9 S hemistry Unit 1 20 Which of the following fuels, when burned, would make no significant contribution to climate change? Hydrogen D Methane Petrol oal (Total for Question 20 = 1 mark) TOTL FOR SETION = 20 MRKS Page 9 of 23

10 S hemistry Unit 1 SETION nswer LL the questions. Write your answers in the spaces provided. 21 (a) n impure sample of sodium hydrogencarbonate, NaHO 3, of mass g, was reacted with an excess of hydrochloric acid. The volume of carbon dioxide evolved was measured at room temperature and pressure and found to be 58.4 cm 3. NaHO 3 + Hl Nal + H 2 O + O 2 The molar volume of any gas at the temperature and pressure of the experiment is 24 dm 3 mol 1. The molar mass of sodium hydrogencarbonate is 84 g mol 1. (i) alculate the number of moles of carbon dioxide given off. (ii) alculate the mass of sodium hydrogencarbonate present in the impure sample. (iii) alculate the percentage purity of the sodium hydrogencarbonate. Give your answer to two significant figures. Page 10 of 23

11 S hemistry Unit 1 (b) (i) The total error in reading the gas syringe is ±0.4 cm 3. alculate the percentage error in measuring the gas volume of 58.4 cm 3. (ii) Suggest why the carbon dioxide should not be collected over water in this experiment. (Total for Question 21 = 7 marks) Page 11 of 23

12 S hemistry Unit 1 22 (a) On strong heating, calcium carbonate decomposes to calcium oxide and carbon dioxide: ao 3 (s) ao(s) + O 2 (g) Owing to the conditions under which the reaction occurs, it is not possible to measure the enthalpy change directly. n indirect method employs the enthalpy changes when calcium carbonate and calcium oxide are neutralized with hydrochloric acid. (i) Write the equation for the reaction of calcium carbonate with hydrochloric acid. State symbols are not required. [ H 1 is the enthalpy change for this reaction]... H 1 (ii) The reaction of calcium oxide with hydrochloric acid is ao(s) + 2Hl(aq) al 2 (aq) + H 2 O(l) H 2 Use the equations in parts (i) and (ii) to complete the Hess s Law cycle below to show how you could calculate the enthalpy change for the decomposition of H reaction. Label the arrows in your cycle. (3) ao 3 (s) H reaction ao(s) + O 2 (g) Page 12 of 23

13 S hemistry Unit 1 H reaction in terms of H 1 and H 2. H reaction = (b) Suggest two reasons why the value obtained by carrying out these two experiments decomposition reaction of calcium carbonate (Total for Question 22 = 7 marks) Page 13 of 23

14 S hemistry Unit 1 23 (a) State how the following processes are achieved in a mass spectrometer. (i) Ionization of the sample. (ii) cceleration of the ions. (iii) Deflection of the ions. (b) State how you could find the molecular mass of a substance from its mass spectrum. In recent years a particular linen cloth was shown, using mass spectrometry, to have been made from flax grown in the early 14th century. Suggest how mass spectrometry can be used to estimate the age of the cloth. (Total for Question 23 = 6 marks) Page 14 of 23

15 S hemistry Unit 1 *24 The melting temperatures of the elements of Period 3 are given in the table below. Use these values to answer the questions that follow. Element Na Mg l Si Melting temperature / K P (white) S (monoclinic) l r (a) Explain why the melting temperature of sodium is very much less than that of magnesium. (3) (b) Explain why the melting temperature of silicon is very much greater than that of white phosphorus. (3) Page 15 of 23

16 S hemistry Unit 1 (c) Explain why the melting temperature of argon is the lowest of all the elements of Period 3. (d) Explain why magnesium is a good conductor of electricity whereas sulfur is a non-conductor. (Total for Question 24 = 9 marks) Page 16 of 23

17 S hemistry Unit 1 25 (a) riefly describe an experiment, with a diagram of the apparatus you would use, which shows that there are oppositely charged ions in copper(ii) chromate(vi), uro 4. Describe what you would expect to see. Formula of ion olour u 2+ (aq) blue Diagram ro 4 2 (aq) yellow (4) (b) The ions in an ionic lattice are held together by an overall force of attraction. (i) Describe the forces of attraction in an ionic lattice. (ii) Suggest two forces of repulsion which exist in an ionic lattice. Page 17 of 23

18 S hemistry Unit 1 (c) Part of the orn-haber cycle for magnesium oxide, MgO, is shown below. Mg 2+ (g) + O(g) E D Mg 2+ (g) + ½O 2 (g) Mg(g) + ½O 2 (g) F Mg(s) + ½O 2 (g) MgO(s) (i) omplete the empty box with the appropriate formulae and state symbols. (ii) Identify the enthalpy changes represented by the letters and (iii) Give the expression for the enthalpy change F in terms of the other enthalpy changes to E. F = Page 18 of 23

19 S hemistry Unit 1 (d) The lattice composed of the ions Mg 2+ and O 2 is stronger than a lattice composed of the ions Mg + and O. (i) Explain, in terms of the charges on the ions and the size of the cations, why this is so. (ii) Suggest how the lattice energy of Mg 2+ O 2 would differ from that of Mg + O. (Total for Question 25 = 15 marks) Page 19 of 23

20 S hemistry Unit 1 26 hloroethane can be made from ethane and chlorine in the gas phase in the presence of ultraviolet light. The equation for the reaction is H 3 H 3 + l 2 H 3 H 2 l + Hl (a) omplete the mechanism for the reaction. Two of the steps have been given for you. (4) Initiation: l 2 2l Propagation (two steps) (i) (ii) Termination (three steps) 2l l 2 (iii) (iv) (b) This reaction gives a poor yield of chloroethane. Give the structural formula and name of another organic product, not included in your mechanism for part (a), which could be produced in the reaction. Formula Name... Page 20 of 23

21 S hemistry Unit 1 (c) hlorine gas is extremely toxic and is therefore a significant hazard. The preparation (i) Explain the difference between hazard and risk. other than the use of a laboratory coat and safety goggles. (Total for Question 26 = 9 marks) Page 21 of 23

22 S hemistry Unit 1 27 n H 2n. However, a compound with this the following. (i) Hydrogen: (ii) Hydrogen bromide to form the major product: (c) Give the mechanism for the reaction of propene with hydrogen bromide, Hr, to form the major product. (3) (Total for Question 27 = 7 marks) TOTL FOR SETION = 60 MRKS TOTL FOR PPER = 80 MRKS Page 22 of 23

23 S hemistry Unit 1 Page 23 of 23