Self Assessment A


1	For the overall hypothetical reaction A + 5B ----> 4C the rate of appearance of C, given by D[C]/Dt, may also be expressed as:
		A)
		B)
		C)
		D)


2	A certain first order reaction, A ----> B, when performed at 25 ^oC, is 46% complete after 68 min. What is the rate constant of this reaction?
		A)	9.06 x 10^-3 min^-1
		B)	1.14 x 10^-2 min^-1
		C)	31 min^-1
		D)	-1.14 x 10^-2 min^-1
		E)	51 min^-1


3	Determine the rate constant for a first order reaction that has a half-life of 26.7 min.
		A)	18.5 min^-1
		B)	38.5 min^-1
		C)	9.25 min^-1
		D)	19.3 min^-1
		E)	0.026 min^-1


4	A second order reaction has a rate constant of 1.0 x 10^-3 Lmol^-1s^-1. If the initial reactant concentration is 0.200 M, how long will it take for the concentration to become 0.0250 M?
		A)	4.0 x 10⁴ s
		B)	3.5 x 10⁴ min
		C)	3.5 x 10⁴ s
		D)	8000 s
		E)	3.5 x 10^-2 s


5	Determine the half-life of a second order reaction with k = 1.0 x 10^-3 Lmol^-1s^-1 if the initial reactant concentration is 0.200 M.
		A)	200 s
		B)	5000 s
		C)	0.005 s
		D)	2 x 10^-4 s
		E)	None of the above.


6	If the rate of the reaction PCl₅ ----> PCl₃ + Cl₂ is increased by a factor of four when the PCl₅ concentration doubles, the rate law for this reaction must be
		A)	dependent on the PCl₃ and Cl₂ concentrations
		B)	first order with respect to PCl₅
		C)	second order with respect to PCl₅
		D)	fourth order with respect to PCl₅


7	If a reaction has a rate constant of 3.7 x 10^-3 s^-1 at 25 ^oC, and an activation energy of 43.6 kJ/mol, what will be the rate constant for this reaction at 75 ^oC?
		A)	A one-step mechanism involving a transition state that contains two hydroxide ions "attached" to the carbon atom of CH₃Cl
		B)	A one-step mechanism involving a transition state that has a carbon partially bonded to both chlorine and oxygen
		C)	A two-step mechanism in which the chlorine leaves CH₃Cl in a slow step, followed by rapid attack of the intermediate by the hydroxide ion
		D)	A two-step mechanism in which the chlorine leaves CH₃Cl in a rapid step, followed by the slow attack of the intermediate by the hydroxide ion


8	A catalyst increases the rate of a reaction by
		A)	increasing the enthalpy of the reaction
		B)	lowering the activation energy of the reaction
		C)	increasing the activation energy of the reaction
		D)	decreasing the enthalpy of the reaction


9	The reaction H₂(g) + I₂(g) ----> 2 HI(g) is exothermic and has the following rate law at 298K: rate = [H₂][I₂]. Addition of a catalyst would
		A)	increase the rate of the forward reaction
		B)	increase the rate of both the forward and reverse reactions
		C)	increase the rate of the reverse reaction
		D)	cause no increase or decrease in the rate of the reaction
		E)	None of the above


10	Which of the following is a likely mechanism for the reaction CH₃Cl + OH^- ----> CH₃OH + Cl^-, which is first order with respect to each of the reactants.
		A)	A one-step mechanism involving a transition state that contains two hydroxide ions "attached" to the carbon atom of CH₃Cl
		B)	A one-step mechanism involving a transition state that has a carbon partially bonded to both chlorine and oxygen
		C)	A two-step mechanism in which the chlorine leaves CH₃Cl in a slow step, followed by rapid attack of the intermediate by the hydroxide ion
		D)	A two-step mechanism in which the chlorine leaves CH₃Cl in a rapid step, followed by the slow attack of the intermediate by the hydroxide ion

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