Question

2HgCl2(aq) + C2O42–(aq) → 2Cl–(aq) +2CO2(g) + Hg2Cl2(s)

The above reaction was studied by the method of initial rates and the following results were obtained:

[HgCl2] (M)

[C2O42–] (M)

Initial Rate (M/min)

0.105

0.15

1.8x10–5

0.105

0.30

7.2x10–5

0.0525

0.30

3.6 x10–5

0.0525

0.15

9.0x10–6

How would you describe the kinetics of this reaction? What is the rate constant?

first-order wrt HgCl2, second-order wrt C2O42–, third-order overall

k = 7.6x10–3 M–2min–1

first-order with respect to (wrt) HgCl2, first-order wrt C2O42–, second-order overall

k = 1.1x10–3 M–1min–1

zero-order wrt HgCl2, second-order wrt C2O42–, second-order overall

k = 5.4x10–5 Mmin–1

first-order wrt HgCl2, second-order wrt C2O42–, second-order overall

k = 4.3x10–8 M–2min–1

Answer 1

Step-by-step explanation:

Expression for rate of the given reaction is as follows.

Rate = k[HgCl_{2}]x [C_{2}O^{2-}_{4}]y[/tex]

Therefore, the reaction equations by putting the given values will be as follows.

`1.8 * 10^(-5) = k[0.105]x [0.15]y` ............. (1)

`7.2 * 10^(-5) = k [0.105]x [0.30]y` ........... (2)

`3.6 * 10^(-5) = k [0.0525]x [0.30]y` ............ (3)

Now, solving equations (1) and (2) we get the value of y = 2. Therefore, by solving equation (2) and (3) we get the value of x = 1.

Therefore, expression for rate of the reaction is as follows.

Rate =
`k[HgCl_(2)]x [C_(2)O^(2-)_(4)]y`

Rate =
`k [HgCl2]1 [C_(2)O^(-2)_(4)]2`

Hence, total order = 1 + 2 = 3

According to equation (1),

`1.8 * 10^(-5) = k[0.105]x [0.15]y`

`1.8 * 10^(-5) = k [0.105]1 [0.15]2`

k =
`7.6 * 10^(-3) M^(-2) min^(-1)`

Thus, we can conclude that rate constant for the given reaction is
`7.6 * 10^(-3) M^(-2) min^(-1)`.