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The molar heat capacity of water at constant pressure, $C_P$ is $75JK^{-1}mol^{-1}$. When 1.0 kJ of heat is supplied to 100 g of water which is free to expand, the increase in temperature of water is

(a) 6.6 K
(b) 1.2 K
(c) 2.4 K
(d) 4.8 K
Is' m' mass or no of moles, it is not clear?

1 Answer

Answer: 2.4 K
Given, Heat supplied to 100 gm of water, Q = 1 kJ = 1000J
mass of water, m =100 g = $\frac{100 g}{18 gmol^{-1}}$ = 5.55 mol
Heat supplied to m gm of water, $Q = mC\Delta t$
$\Delta t = \frac{Q}{mC} = \frac{1000J}{\text{5.55 mol} \times 75 JK^{-1}mol^{-1}}$ = 2.4 K
answered Feb 25, 2014 by mosymeow_1

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