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NCERT Class XI Chemistry Thermodynamics Solutions

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Question : 9 of 22
Marks: +1, -0
Calculate the number of kJ of heat necessary to raise the temperature of 60.0 g of aluminium from 35°C to 55°C. Molar heat capacity of Al is 24 J mol−1 K−1\mathrm{J}\,\mathrm{mol}^{-1}\,\mathrm{K}^{-1}.
Solution:  
Mass of Al = 60 g
Rise in temperature, ΔT = 55 – 35 = 20°C
Molar heat capacity of Al = 24 J mol−1 K−1\mathrm{J}\,\mathrm{mol}^{-1}\,\mathrm{K}^{-1}
Specific heat capacity of Al = 2427 J g−1 K−1\frac{24}{27}\,\mathrm{J}\,\mathrm{g}^{-1}\,\mathrm{K}^{-1}
∴ Energy required = m × c × ΔT = 60 × 2427\frac{24}{27} × 20 = 2880027\frac{28800}{27} = 1066.67 J
= 1.067 kJ or 1.07 kJ
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