Question

Molar heat capacity of aluminium is $ 25\text{ }J{{K}^{-1}} $ $ mo{{l}^{-1}} $ . The heat necessary to raise the temperature of $54 \,g$ of aluminium (atomic mass $ 27\text{ }g\text{ }mo{{l}^{-1}}. $ from $ 30{}^\circ C $ to $ 50{}^\circ C $ is

• A. $1.5\, kJ$
• B. $0.5\, kJ$
• C. $1.0\, kJ$
• D. $2.5\, kJ$
• E. $2.0\, kJ$

Answer 1

Answer: (C)

The heat required to raise the temperature of 54 g of aluminium from
$ 30{}^\circ $ to $ 50{}^\circ C $ $ q=nC({{T}_{2}}-{{T}_{1}}) $ where n = moles of substance C = molar heat capacity
$ =\frac{Mass\text{ }of\text{ }aluminium\text{ }(g)}{Molar\text{ }mass\text{ }of\text{ }aluminium}\times C\times \Delta T $
$ =\frac{54}{27}\times 25\times 20\,J $
$ (\Delta T=50-30=20{}^\circ C) $
$ =1000\text{ }J=1.0\text{ }kJ $