Question

$100 g$ of water is heated from $30^{\circ} C$ to $50^{\circ} C$. Ignoring the slight expansion of the water, the change in its internal enetgy is (specific heat of water is $4184 J / kg / K )$

• A. $2.1 kJ$
• B. $4.2 kJ$
• C. $8.4 kJ$
• D. $84 kJ$

Answer 1

Answer: (C)

$Q=\Delta U+W$
As $W=0$
$ \Rightarrow \Delta U=Q$
$=4184 \times \frac{100}{1000} \times 20$
$=8368$
$=8.368 kJ$
$\approx 8.4 kJ$