Question

The heat required to rise the temperature of $54 \,g$ of aluminium from $40^{\circ} C$ to $60^{\circ} C$ in $J$ is (molar heat capacity of aluminium in this temperature range is $24\, J\, mol ^{-1} K ^{-1}$; atomic weight of $Al$ is $27$ )

• A. 480
• B. 800
• C. 960
• D. 1280

Answer 1

Answer: (C)

Given,

Weight of aluminium $(w)=54 \,g$

Temperature difference $(\Delta T)=60^{\circ}-40^{\circ}=20^{\circ} C$

Molar heat capacity of aluminium

$\left(C_{s}\right)=24 \,J \,mol ^{-1} K ^{-1}$

Atomic mass of $( Al )$, i.e. $(M)=27$

$\therefore $ Moles of $( Al )$, i.e. $n=\frac{w}{M}$

$=\frac{54}{27}=2 \,mol$

Heat required $(Q)=n C_{s} \Delta T$

$=2 \times 24 \times 20=960 \,J$