For the reaction of one mole of zinc dust with one mole of 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
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what should be the answer of this question according to you and why please explain in detail.

Correct Answer: A

Solution :

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. ∆U < 0, w = 0

ΔU=q+w
In a bomb calorimeter,ΔV=0,
∴w=−PΔV=0
Also,q=(−) as process is exothermic
∴ΔU<0