Question

A hypothetical reaction $A\to 2B$, proceeds through following sequence of steps:
(i) $A\to C;\Delta H=q$
(ii) $C\to D;\Delta H=v$
(iii) $\frac{1}{2}D\to B;\Delta H=x$
Then the heat of reaction is:

• A. $q-v+2x$
• B. $q+v-2x$
• C. $q+v+2x$
• D. $q+2v-2x$

Answer 1

Answer: (C)

$q+v+2x$

$A\to C,\Delta H=q$ ...(1)

$C\to D,\Delta H=v$ ....(2)

$1/2D\to B,\Delta H=x$ ..(3)

From (3) ,$D\to 2B,\Delta H=2x$ ...(4)

Now adding equations (1)+(2)+(4) we get:

$A\to 2B,\Delta H=q+v+2x$