Chemistry 1105 R11 Fall 2018 Test 3

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1 Chemistry 1105 R11 Fall 2018 Test 3 Friday, November 16, 2018 Name: Time: 1 hour 50 minutes Student #: This test consists of seven pages of questions, the periodic table, and a page containing useful constants and conversions. Please ensure that you have a complete paper and, if you do not, obtain one from me immediately. There are 35 marks available. Good luck! 1) [3 marks] A gas of formula SOn has a density of 2.00 g/l at C and 0.61 atm of pressure. What is the value of n? 2) [4 marks] A gas mixture contains seven times as many moles of Gas B as of Gas A. The total pressure inside the container holding the gases is 800 torr. a) What is the mole fraction of each gas? b) What is the partial pressure of each gas?

2 3) [3 marks] My watch may be submerged under 150 metres of water without being damaged. If the density of water is 1.00 g/cm 3, to how many bar of pressure does this depth of water correspond? 4) [3 marks] A 2.0-litre container had 1500 ml of water placed in it. After that, an unknown metal of mass grams was added to the container, and the container quickly sealed. The following reaction took place: 2M(s) + 2H2O(l) 2MOH(aq) + H2(g) The temperature and total pressure of the gas mixture were measured after the reaction. They were found to be 24.2 C and 1000 torr, respectively. If atmospheric pressure was torr, and the vapour pressure of water was 22.6 torr, what was the metal, M? (Assume the volume of water does not change because of the reaction.) 2

3 5) [4 marks] A piece of copper of mass grams (S = J/g C) at 90.0 C was placed in 150 grams of water (S = J/g C) at 25 C. The water was contained in a cup of unknown heat capacity. If the final temperature of the water was 48 C, what was the heat capacity of the cup? Be sure to include proper units in your answer. 6) [3 marks] In one experiment, 1.00 grams of NaOH (40.0 g/mol) was reacted with ml of M H2SO4 (S = J/g C, D = 1.00 g/mol) at C: 2NaOH(s) + H2SO4(aq) Na2SO4(aq) + 2H2O(l) The final temperature of the solution was C. Calculate ΔH for the reaction above. 3

4 7) [3 marks] Given the following: 8H2(g) + S8(s) + 16O2(g) 8H2SO4(aq) ΔH = kj 2Na(s) + O2(g) + H2(g) 2NaOH(s) ΔH = kj 2H2(g) + O2(g) 2H2O(l) ΔH = kj 16Na(s) + S8(s) + 16O2(g) 8Na2SO4(aq) ΔH = kj Calculate H for the reaction: 2NaOH(s) + H2SO4(aq) Na2SO4(aq) + 2H2O(l) 4

5 8) [4 marks] Given the thermochemical equation: C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) ΔH = kj How many kj of heat would you expect to be evolved when the valve on the following apparatus was opened: C3H8 O2 2 atm, 1 L 9 atm, 1 L C C 5

6 9) [2 marks] Given the following: Compound ΔH f (kj/mol) NaOH(s) H2SO4(aq) Na2SO4(aq) H2O(l) Calculate ΔH for the reaction 2NaOH(s) + H2SO4(aq) Na2SO4(aq) + 2H2O(l) 10) [4 marks] Given the following equilibrium: H2(g) + Cl2(g) 2HCl(l) ΔH < 0 Predict the effect that each of the changes given below would have on the value of Kc and on the moles of HCl present in a fresh system initially at equilibrium. Your choices are Increase from the starting value, Decrease from the starting value, or Not Change from the starting value. You may assume that, unless explicitly stated otherwise, the changes were carried out at constant temperature. Kc Effect on: HCl Removing some Cl2 I D NC I D NC Heating the reaction mixture I D NC I D NC Increasing the volume I D NC I D NC Adding some H2 I D NC I D NC 6

7 11) [2 marks] Given the following equilibrium: 4PH3(g) P4(s) + 6H2(g) Kc = 1.02 x10 3 Calculate Kc for: 1.5H2(g) P4(s) PH3(g) 7

Chemistry 1110 R10 Spring 2015 Test 1

Chemistry 1110 R10 Spring 2015 Test 1 Thursday, January 29, 2015 Time: 1 hour 50 minutes Name: Student Number: This test consists of nine pages of questions, a page of useful constants, and a periodic