Question

Total order of reaction $X+Y\to XY$ is 3.
The order of reaction with respect to X is 2.
State the differential rate equation for the reaction.

• A. $-\frac{d\left[X\right]}{dt}=k\left[X{]}^o\right[Y{]}^3$
• B. $-\frac{d\left[X\right]}{dt}=k\left[X{]}^3\right[Y{]}^0$
• C. $-\frac{d\left[X\right]}{dt}=k\left[X{]}^2\right[Y]$
• D. $-\frac{d\left[X\right]}{dt}=k\left[X\right][Y{]}^2$

Answer 1

The correct option is C $-\frac{d\left[X\right]}{dt}=k\left[X{]}^2\right[Y]$

The sum of powers of the concentrations of the reactants in the rate law expression is called the order of that chemical reaction
$X+Y\to XY$
The order of reaction with respect to $X$ is $2.$
$\therefore -\frac{d\left[X\right]}{dt}=k\left[X{]}^2\right[Y]$
Total order of reaction $=2+1=3$