Question

From the rate equation for the reaction given below, determine the order with respect to the overall reaction:

$\left(i\right)2HCr{O}_4^{-}+6I^{-}+14H^{+}\to 2C{r}^{3+}+3I_2+8H_{2}O$

$Rate\propto \left[HCr{O}_4^{-}\right]{\left[I^{-}\right]}^2{\left[H^{+}\right]}^2$

• A. 5
• B. 22
• C. 4
• D. 9

Answer 1

The correct option is A 5

Order of a reaction:
For a given reaction:
$aA+bB+cC\to \text{Products}$
If,
$\text{Rate}\propto \left[A{]}^p\right[B{]}^q[C{]}^r$
Overall order of the reaction is :
$(p+q+r)$

So, for
$2HCr{O}_4^{-}+6I^{-}+14H^{+}\to 2C{r}^{3+}+3I_2+8H_{2}O$

Given,
$\text{Rate}\propto \left[HCr{O}_4^{-}\right]{\left[I^{-}\right]}^2{\left[H^{+}\right]}^2$

$\text{Overall order}=1+2+2=5$