Question

Molar heat capacity of aluminium is $25J{K}^{-1}mo{l}^{-1}$. The heat necessary to raise temperature of $54g$ of aluminium (Atomic mass $27gmo{l}^{-1}$) from ${30}^{o}C$ to ${50}^{o}C$ is:

• A. $1.5kJ$
• B. $0.5kJ$
• C. $1.0kJ$
• D. $2.5kJ$

Answer 1

The correct option is C $1.0kJ$

Solution:- (C) $1.0kJ$

Mass of $Al=54g$

Molar mass of $Al=27g/mol$

$\therefore$ No. of moles $\left(n\right)=\frac{54}{27}=2\text{mole}$

$\Delta T=50-30=20$

Molar heat capacity $\left(C\right)=25J/mol-K$

$\therefore$ Total heat required $=nC\Delta T$

$\Rightarrow$ Total heat required $=2\times 25\times 20=1000J/mol-K=1kJ/mol-K$

The heat necessary to raise the temperature is $1.0kJ$.