`A_(2)B` is an ideal gas , which decompase according f to the equation : `A_(2) B to A_(2) + (1)/(2)B_(2)` . At start , the initial pressure is 100 mm Hg and after 5 minutes , the pressure is 120 mm Hg. What is the average rate of decomposition of `A_(2)B` ? Assume T and V are constant .

Explanation

The decomposition reaction of gaseous `A_(2)B` is given as `A_(2)B to A_(2)+(1)/(2)B_(2)`
`100 0 0` at start of the reaction
`100-2x 2x x` after the reaction
`100-2x+2x+x=100+x=120"mm"`
`x=20mm "or" 2x=40mm`
The decrease in pressure of reactant substance, `A_(2)B` in `5` min is `40` mm.
The rate of decomposition of `A_(2)B=(40)/(5)`
`8 "mm min"^(-1)=0.133"mm" s^(-1)`