Consider the following reaction between mercury(II) chloride and oxalate ion. Th

Question

Consider the following reaction between mercury(II) chloride and oxalate ion.

The initial rate of this reaction was determined for several concentrations of HgCl2 and C2O42-, and the following rate data were obtained for the rate of disappearance of C2O42-.

A) What is the value of the rate constant? _________ M^(-2)s^(-1)

B)What is the reaction rate when the concentration of HgCl2 is 0.18 M and that of C2O42- is 0.11 M if the temperature is the same as that used to obtain the data shown above? __________ M/s

Experiment [HgCl2] (M) [C2O42-] (M) Rate (M/s) 1 0.164 0.15 3.2 10-5 2 0.164 0.45 2.9 10-4 3 0.082 0.45 1.4 10-4 4 0.246 0.15 4.8 10-5

Explanation / Answer

Let the rate be represented as

-r = K[ HgCl2]m [C2O4-]n

From experiment 1

K[ 0.164]m [0.15]n = 3.2*10-5   (1)

From experiment 2

K[ 0.164]m [0.45]n = 2.9*10-4   (2)

Eq.2/ Eq.1 give   [3]n= 29/3.2=9, n=2

From experiment 3

K[ 0.082]m [0.45]n = 1.4*10-4   (3)

From experiment 4

K[ 0.246]m [0.15]n = 4.8*10-5   (4)

Eq.4/Eq.1 = (0.246/0.164)m= (4.8/3.2)=1.5, m=1

So the rate becomes

-r = K[ HgCl2]1 [C2O4-]2

From Eq.1, 3.2*10-5= K [0.164 [0.15]2 =K*0.00369

K= 3.2*10-5/0.00369=0.008672/M2.S

b) for [HgCl2]= 0.18M and [C2O4-2]= 0.11 M -r = 0.008672*0.18*(0.11)2 =1.888*10-5M/S

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