UB CHE 102LEC - 2017Fall-CHE102-E1-Practice-Ans (8 pages)

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2017Fall-CHE102-E1-Practice-Ans



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2017Fall-CHE102-E1-Practice-Ans

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Exam w/ answers


Pages:
8
School:
University at Buffalo-SUNY
Course:
Che 102lec - General Chemistry Lecture
Unformatted text preview:

CHEM 102 112 Exam 1 March 3rd 2017 1 hr 30 min 1 Fill in this cover sheet 1 On the Answer Sheet under Exam Information Test Version bubble in your version which is located next to your signed name on this cover sheet if not filled in your paper will not be graded 2 On the Answer Sheet under Student Information STUDENT ID write your 8 digit UB person number vertically bubble in the numbers Integrity Certification Sign your name stating you will not cheat on this exam NAME print your first name last name and your UBIT name from your email 3 Check that you have a complete examination 10 pages including Formula Sheet and Periodic Table Print your name on the top of every page of the Examination and hand in ALL pages when you are done 4 To answer a question fill in the circle on the bubble sheet that corresponds to the BEST answer You may use a pencil or a pen blue or black ink only and no felt tips If you decide to change your answer write an X over the incorrect answer fill in the new correct answer and write the letter for the correct answer to the left of the question number Questions with more than one answer marked and not written as stated above will be graded as incorrect The only answers accepted are those which appear on the bubble sheet There are 25 questions 4 points each Total possible points 100 PLEASE READ AND SIGN THE ACADEMIC HONESTY STATEMENT BELOW I hereby certify that the answers given represent my own unaided work Signed Test Version A Printed Name Person Number Day Time of Recitation Name of TA Recitation Code Name 1 Consider the following pairs of liquids Which pairs are miscible I II III Benzene C6H6 and Hexane C6H14 Water and Methanol CH3OH Water and Hexane A I II only B II only C I only D III only E I II III 2 What are the ideal van t Hoff factors for the following compounds BaF2 C6H12O6 K3PO4 NH4 2SO4 A B C D E 1 1 1 1 3 1 4 1 3 1 4 3 2 3 5 5 None of the above 3 A solution made by dissolving 9 81 g of a nonvolatile nonelectrolyte in 90 0 g of water boiled at 100 37 C and 760 1 mmHg What is the approximate molecular weight in g mol of the nonelectrolyte substance Kb Normal Boiling Normal Freezing Substance A B C D E 240 150 79 61 34 Water Point C C m Point C Kf C m 100 00 0 51 0 00 1 86 4 At 20 C and 1 00 atm of partial pressure of O2 the solubility of O2 in water is 1 38x10 3 M At sea level however the partial pressure of O2 is 0 21 atm Calculate the concentration M of O2 in water at sea level A B C D E 1 4x10 3 6 6x10 3 2 9x10 4 0 21 None of these answers are correct 2 Name 5 Hw During the formation of a solution which step is always an exothermic process A B C D E Only the separation of solvent particles to accommodate solute particles Hsolvent The mixing of solute particles and solvent particles with one another Hmix The overall solution process HSoln Only the separation of solute particles from one another Hsolute The separation of solute and solvent particles from one another Hsolute and Hsolvent 6 A solution is prepared by dissolving 23 7 g of aspirin C9H8O4 in 375 g of water The density of the resulting solution is 1 05 g mL What is the molar concentration of aspirin A B C D E 0 347 0 35 54 7 878 0 063 7 Of the concentration units below only is temperature dependent A B C D E mass ppm mole fraction molarity molality 8 What is the osmotic pressure in atm of a solution formed by dissolving 25 0 mg of CaCl2 in 250 mL of water at 25 C A B C D E 7 34 9 01x10 4 0 0661 0 0220 2 25x10 4 3 Name 9 The combustion of ethane C2H6 is represented by the equation below in this reaction 2C2H6 g 7O2 g 4CO2 g 6H2O l A the rate of consumption of ethane is seven times faster than the rate of consumption of oxygen B the rate of formation of CO2 equals the rate of formation of water C water is formed at a rate equal to two thirds the rate of formation of CO2 D CO2 is formed twice as fast as ethane is consumed E the rate of consumption of oxygen equals the rate of consumption of water 10 The half life for a first order reaction is 32 sec What was the original concentration M if after 2 0 minutes the reactant concentration is 0 062 M A B C D E 0 84 0 069 0 091 0 075 0 13 11 Given that a forward reaction is endothermic with an activation energy of 50 kJ mol which of the following statements are correct I The reverse reaction has an activation energy equal to 50 kJ mol II The reverse reaction has an activation energy less than 50 kJ mol III The reverse reaction has an activation energy greater than 50 kJ mol IV The reverse reaction will be endothermic V The reverse reaction will be exothermic A I IV B II IV C III IV D II V E III V 12 Which items correctly complete the following statement A catalyst can act in a chemical reaction to I II III IV Increase the equilibrium constant Lower the activation energy Decrease H for the forward reaction Provide a new path for the reaction A I II B II III C III IV D I III E II IV 4 Name 13 What is the difference between average rate and instantaneous rate In a given reaction can these two rates ever have the same numeric value A An instantaneous rate is measured at a particular point in time of a reaction whereas the average rate is measured over a time period They can have the same numeric value B An instantaneous rate is measured at a particular point in time of a reaction whereas the average rate is measured over a time period They can t have the same numeric value C An instantaneous rate is measured over a short time period whereas the average rate is measured over a large time period They can have the same numeric value D An instantaneous rate is measured over a short time period whereas the average rate is measured over a large time period They can t have the same numeric value E An instantaneous rate is calculated from the slope of 2 points on the graph whereas the average rate is calculated from a tangent line They can have the same numeric value 14 Hw A second order reaction will yield a straight line when time is plotted …


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