2008 Rate Question #2

(a) order with respect to A = zero

(b) order with respect to B = 2

(c) rate = k [A]0 [B] 2 or  rate = k [B]2

(d) k = 0.577 L/mol s  (or comparable units)

(e) rate for experiment #4 is 0.0313 M/sec

(f) (i) The two steps add together to give the overall reaction.  (ii) The rate of the slow step is the same as the rate of the overall reaction.

You could also say (iii) Substance A is not involved in the slow step of the reaction, which is consistent with a rate law that is zero order in A.

(g) Species E is an intermediate, because it is formed in step 1 and consumed in a later step.

2009 Rate Question #2

(a) the concentration of thiosulfate

(b) The reaction is FIRST ORDER .  You could prove by dividing one experiment by another to find the exponent, or by noting that the graph of rate vs concentration is a straight line.

(c) k = 0.40 s-1

(d) 4.0 seconds

(e) Sketch a straight line that starts lower on the y axis and has a less steep slope.