Question

Three statements are given below:

i) The amount of heat evolved when 500 ml of 1 M $H_{2}S{O}_4$ is mixed with 250 ml of 1 M $NaOH$ solution is $-28.65$ kJ.

ii) The amount heat evolved when 1 litre of 1 M $C{H}_{3}COOH$ is neutralised with 1 litre of 1 M $NaOH$ solution is $-13$ kcal. The heat of dissociation of acetic acid is 0.4 kcal.

iii) The standard heat of combustion of graphite is equal to standard heat of formation of $C{O}_2$.

• A. All are correct
• B. i and ii are correct
• C. i, ii and iii are correct
• D. ii and iii are correct

Answer 1

The correct option is D ii and iii are correct

(i) $NaOH$ is limiting reagent. Thus heat evolved should be $-14.2$ kJ.
(ii) Heat of dissociation + Heat of neutralization of CH${}_3$COOH$=$ 13.7 kcal
$\therefore H_{diss}=13.7-13.3$
$\Delta H_{diss}=$ 0.4 kcal
(iii) $C+O_2\to C{O}_2$
The combustion of graphite is same as standard heat of formation of $C{O}_2$.