Question

***30 POINTS***

Which statement is correct regarding the reaction below?

3A + 2B yields C + 2D

A) The rate of formation of D is twice the rate of disappearance of A.
B) The rate of disappearance of A is one-third the rate of formation of C.
C) The rate of formation of C is twice the rate of appearance of D.
D) The rate of disappearance of B is twice the rate of appearance of C.1

Answer 1

It's not B so I'm thinking it is D.

Answer 2

Answer: D) The rate of disappearance of B is twice the rate of appearance of C.

Explanation: Rate of a reaction is defined as the rate of change of concentration per unit time.

Thus for reaction:
`3A+2B\rightarrow C+2D`

The rate in terms of reactants is given as negative as the concentration of reactants is decreasing with time whereas the rate in terms of products is given as positive as the concentration of products is increasing with time.

`Rate=-(1d[A])/(3dt)=-(1d[B])/(2dt)=+(d[C])/(dt)=+(1d[D])/(2dt)`

Thus : Rate of formation of D=
`(d[D])/(dt)]=-(2)/(3)* {\text {rate of disappearance of A}}`

Rate of disappearance of A=
`-(d[A])/(dt)=3* {\text {rate of appearance of C}}`

Rate of formation of C=
`+(d[C])/(dt)=+(1)/(2)* {\text {rate of appearance of D}}`

Rate of disappearance of B=
`-(d[B])/(dt)=2* {\text {rate of appearance of C}}`