Test 4 first letter of last name Chemistry 10 Dr Kline February 10 2010 Name This test consists of a combination of multiple choice and other questions There should be a total of 16 questions on four pages please check to make sure that they are all here Do not use your own tables scratch paper or other information Please turn off all cell phones pagers and other communication devices they will be confiscated if they make noise No food No water No gum No bathroom breaks A regular calculator is OK but you may not use graphing or programmable calculators and they will be confiscated if they are discovered during the test The test will end 90 minutes after it starts The last page is an info sheet that you may separate from the rest of the test please check out the information on said sheet before asking questions about missing information in the body of the test Multiple Choice Questions These eleven questions are worth four points each for a total of 44 points Unless it is stated otherwise in a given problem there is only one correct answer for each question giving 1 answer for those questions will give you zero points Answer each question by circling all letter s corresponding to the correct choice s If more than one answer is correct you should circle all of the correct ones It is not necessary to show work for these questions however you may write on the exam 1 Which of the following aqueous solutions is are acidic at 25 C More than one answer may be correct a 0 10 M HF b 0 10 M F c one with H 2 2 10 8 M d one with HO 1 3 10 6 M e none of them 2 Which of the following has the higher boiling point H a H H C C H H H O H H b C H H O C H H c it is impossible to tell 3 Which of the following molecules has the greatest vapor pressure at 35 C a CH2Br2 b CH2Cl2 c CH2I2 d it is impossible to tell 4 Which of the following processes is are endothermic More than one may be a melting b sublimation c freezing d condensation e none of them 5 Which of the following aqueous solutions at 25 C has the highest pH a 0 10 M HCl b 0 10 M HClO c 0 10 M LiOH d 0 10 M ClO with neutral cation Page 1 of 5 Test 4A Chem 10 Winter 2010 6 Which of the following 500 mL aqueous solutions has the greatest molar concentration M a one that contains 25 g KCl b one that contains 25 g NaCl c one that contains 50 g KCl d one that contains 50 g NaCl 7 Suppose that 250 mL of aqueous 1 2 M HNO3 solution is diluted to a total volume of 400 mL What is the pH of the resulting solution a 0 12 b 0 20 c 0 28 d 0 79 e it is impossible to tell 8 A homogeneous gas phase reaction has the equilibrium expression below Which of the following is the corresponding reaction equation K N2 Br2 3 NBr3 2 a N2 g 3Br2 g 2NBr3 g b 2NBr3 g N2 g 3Br2 g c N2 g 3Br2 l 2NBr3 g d 2NBr3 g N2 g 3Br2 l e none of these 9 Which of the following is are true for the reaction Cr s NiCl2 aq CrCl3 aq Ni s More than one answer may be correct a NiCl2 is the oxidizing agent b Cr metal is reduced c Three electrons are transferred in the balanced equation d Electrons are transferred from Cr metal to Ni2 ion e None of the above because this is not an oxidation reduction reaction 10 Consider the endothermic reaction C s CO2 g 2CO g Which of the following changes made to the reaction at equilibrium will cause it to shift to the left More than one answer may be correct a increase the temperature b add a small amount of C s c decrease the volume of the reaction container d remove some CO2 g e none will 11 Consider a sample of Xe gas that occupies 235 mL at 57 C and 757 mm Hg Which of the following changes would cause the pressure of xenon inside the container to increase More than one answer may be correct a Increase the volume of the container to 277 mL temperature remaining constant b Increase the temperature of the container to 67 C volume remaining constant c Add some He gas to the container without letting any of the Xe escape temperature and volume remaining constant d Increase the temperature to 62 C and decrease the volume to 205 mL e None would Page 2 of 5 Test 4A Chem 10 Winter 2010 Other Questions Each of the following questions is worth the indicated number of points for a total of 56 points Please be sure to provide all of the information requested for each question Show work with units for all problems 12 10 points Suppose that a balloon is inflated to a volume of 6510 mL using 0 296 moles of helium gas Sadly the balloon develops a leak whereupon it deflates to a volume of 5550 mL before the leak is plugged How many moles of gas escaped Assume that the temperature and pressure remain constant 13 12 points Carbon dioxide gas is generated by the reaction between potassium carbonate and HCl Suppose that 125 mL of 2 5 M HCl is reacted with excess K2CO3 What volume of CO2 gas collected at 27 C and 753 torr would result The formula weight of K2CO3 is 138 21 g K2CO3 aq 2HCl aq 2KCl aq CO2 g H2O l Page 3 of 5 Test 4A Chem 10 Winter 2010 14 12 points Calcium hydroxide dissolves to some extent in water At 25 C a saturated solution of calcium hydroxide has Ca OH 2 1 11 10 2 M and a density of 1 00 g mL The formula weight of Ca OH 2 is 74 09 g a Calculate the pH of the solution b Calculate the percent by mass concentration of Ca OH2 in the solution 15 12 points The reaction 2CH4 g C2H2 g 3H2 g has K 0 154 at 1700 C If CH4 0 0200 M and H2 0 112 M at equilibrium what is C2H2 at equilibrium 16 10 points Balance the reaction below which occurs in aqueous acid solution by the half reaction method Show work Fe2 aq IO3 aq Fe3 aq I2 s Page 4 of 5 Test 4A Chem 10 Winter 2010