Properties Of Solids And Liquids Question 416
Question: A mass of 50g of water in a closed vessel, with surroundings at a constant temperature takes 2 minutes to cool from $ 30{}^\circ C $ to$ 25{}^\circ C $ . A mass of 100g of another liquid in an identical vessel with identical surroundings takes the same time to cool from $ 30{}^\circ C $ to $ 25{}^\circ C $ . The specific heat of the liquid is: (The water equivalent of the vessel is 30g.)
Options:
A) 2.0 kcal/kg
B) 7 kcal/kg
C) 3 kcal/kg
D) 0.5 kcal/kg
Show Answer
Answer:
Correct Answer: D
Solution:
[d] $ \frac{( m _{w}C _{m}+W )\Delta T}{t}=\frac{( {m _{\ell }}{C _{\ell }}+W )\Delta T}{t} $ (W=water equivalent of the vessel) or $ m _{w}C _{w}={m _{\ell }}{C _{\ell }} $
$ \therefore $ Specific heat of liquid, $ C=\frac{m _{w}C _{w}}{{m _{\ell }}} $
$ =\frac{50\times 1}{100}=0.5kcal/kg $
