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

2 hgcl2(aq) + c2o42-(aq) 2 cl -(aq) + 2 co2(g) + hg2cl2(s)

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-.
experiment [hgcl2] (m) [c2o42-] (m) rate (m/s)
1 0.164 0.15 3.2x10^-5
2 0.164 0.45 2.9x10^-4
3 0.082 0.45 1.4x10^-4
4 0.246 0.15 4.8x10^-5

what is the rate law for this reaction?
(a) -k[hgcl2][c2o4-2]2-
(b) -k[hgcl2]2[c2o4-2]
(c) -k[hgcl2]2[c2o4-2]1/2

The rate law of the reaction is

Explanation:

Rate law is defined as the expression which expresses the rate of the reaction in terms of molar concentration of the reactants with each term raised to the power their stoichiometric coefficient of that reactant in the balanced chemical equation.

For the given chemical equation:

Rate law expression for the reaction:

where,

a = order with respect to

b = order with respect to

Expression for rate law for first observation:

 ....(1)

Expression for rate law for second observation:

 ....(2)

Expression for rate law for third observation:

 ....(3)

Expression for rate law for fourth observation:

 ....(4)  

Dividing 2 from 1, we get:

Dividing 2 from 3, we get:

Thus, the rate law becomes: