`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)BtoA_(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=120mm`
`x=20` mm or `2x=40` mm
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)`.