Calculate the quantity of heat needed to change the temperature of 60g of ice at...
PHYSICS
WAEC 2019
Calculate the quantity of heat needed to change the temperature of 60g of ice at 0 °C to 80 °C. [specific latent heat of fusion of ice= 3.36 x 10\(^5\) Jkg\(^{-1}\) specific heat capacity of water 4.2 x 10\(^3\) J kg\(^{-1}\) K\(^{-1}\)]
- A. 4.80 kJ
- B. 20.16 kJ
- C. 40.32 kJ
- D. 22.17 kJ
Correct Answer: C. 40.32 kJ
Explanation
Heat needed to change 60g (0.06kg) of ice at 0\(^o\)C to water at 0\(^o\)
= 0.06 x 3.36 x 10\(^5\)J
= 0.2016 x 10\(^5\) J
Heat required to raise the temp. of 60g (0.06kg) of water from 0\(^o\)C to 80\(^o\)C
= 0.06 x 4.2 x 10\(^3\) x (80.0)J
= 0.06 x 4.2 x 10\(^3\) x 80
= 20.16 x 10\(^3\)
= 0.2016 x 10\(^5\)
Total heat needed = (0.2016 + 0.2016) 10\(^5\)J
= 0.4032 x 10\(^5\) J
= 40.32KJ
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