Heat is added to 10^3 cubic cm of water at atmospheric pressure. The water's temperature increases by 50 degrees celsius. Find (a) the work done by the water as it expands (b) the increase in water's internal energy.

Asked by arjunsah797 | 1st Mar, 2022, 03:01: PM

Expert Answer:

Workdone = P ΔV 
 
where P = 1.01 × 105 Pa  is pressure that is kept constant during expansion and ΔV is change in volume
 
ΔV = Vi β ΔT  
 
where Vi = 103 × 10-6 m3  is initial volume , β = 210 × 10-6 /°C is volume expansion coefficient and ΔT = 50 °C is change in temperature .
 
ΔV = 103 × 10-6 × 210 × 10-6 × 50 = 1.05 × 10-5 m3 
 
Workdone = P ΔV = 1.01 × 105 × 1.05 × 10-5 = 1.060 J
 
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Chane in internal energy ΔU = m Cp ΔT
 
where m is mass of water , Cp is specific heat and ΔT is change in temperature
 
mass of water m = volume × density = 103 × 10-6 × 1000 = 1 kg
 
Chane in internal energy ΔU =1 × 4186 × 50 = 2.093 × 105 J  = 209.3 kJ

Answered by Thiyagarajan K | 1st Mar, 2022, 04:54: PM