1 g of water is evaporated at 1 atmospheric pressure. Its volume in liquid phase is 1 cm 3 which becomes 1671 cm 3 in the vapour phase. If the latent heat of water is 2256 J / g , then change in its internal energy is

Question

1 g of water is evaporated at 1 atmospheric pressure. Its volume in liquid phase is 1 cm 3 which becomes 1671 cm 3 in the vapour phase. If the latent heat of water is 2256 J / g , then change in its internal energy is (A) 816 J (B) 1587 J (C) 2087 J (D) 3102 J

Tardigrade Admin · Accepted Answer

Δ Q=Δ U+P Δ V For 1 g of water, Δ Q=2256 J Δ W=P Δ V=(1.013 × 105 Pa )[1670 × 10-6] m 3=169 J ⇒ Δ U=Δ Q-P Δ V=(2256-169) J =2087 J

Q. 1 g of water is evaporated at 1 atmospheric pressure. Its volume in liquid phase is $1 c m^{3}$ which becomes $1671 c m^{3}$ in the vapour phase. If the latent heat of water is $2256 J / g$ , then change in its internal energy is

816 J

1587 J

2087 J

3102 J

$Δ Q = Δ U + P Δ V$
For $1 g$ of water, $Δ Q = 2256 J$
$Δ W = P Δ V = (1.013 \times 1 0^{5} P a) [1670 \times 1 0^{- 6}] m^{3} = 169 J$
$\Rightarrow Δ U = Δ Q - P Δ V = (2256 - 169) J = 2087 J$

Q. 1 g of water is evaporated at 1 atmospheric pressure. Its volume in liquid phase is 1cm3 which becomes 1671cm3 in the vapour phase. If the latent heat of water is 2256J/g, then change in its internal energy is