Question

For the reaction of one mole zinc dust with one mole sulphuric acid in a bomb calorimeter, $△U$ and w correspond to?

• A. $△U<0,w=0$
• B. $△U<0,w<0$
• C. $△U>0,w=0$
• D. $△U>0,w>0$

Answer 1

Answer: (A)

$△U<0,w=0$

$Zn\left(s\right)+H_{2}S{O}_4\left(g\right)\rightleftharpoons ZnS{O}_4\left(s\right)+H_2\left(g\right)$

${\Delta }_{n_{gas}}=0$

$\therefore w={\Delta }_{n_{gas}}RT=0$

$\Delta U=w+q$

Bomb calorimeter is commonly used to find the heat of combustion of organic substances which consists of a sealed combustion chamber, called a bomb. If a process is run in a sealed container then no expansion or compression is allowed, so w = 0 and ∆U = q.

$\therefore q<0$

$\therefore \Delta U<0$

Hence, the correct option is $\text{A}$