Answer to Question #198711 in Classical Mechanics for Kate McClue

Question

1. How much energy is required to melt a 0.5kg block of ice?

1. Calculate the specific latent heat of fusion of naphthalene given that 6x10⁵J of heat are given out when 4.0kg of naphthalene at its melting point changes to a solid.

1. How much energy and time does a 2200w kettle require to evaporate 0.5kg of water at 100⁰C? (Specific latent heat of vaporization of water = 2.26x10⁶J/kg)

1. Calculate the amount of heat energy required to melt 0.3 kg of ice at 0 °C.

(Specific latent heat of fusion of ice = 3.34 x 10⁵ J/kg)

1. What is the difference between latent heat of fusion and latent heat of vaporisation of a substance?

Answer 1

1.

$Q=\lambda m=3.34\cdot 10^5\cdot 0.5=167~kJ.$

2.

$\lambda=\frac Qm=\frac{6\cdot 10^5}{4}=1.5\cdot 10^5~\frac {J}{kg}.$

3.

$P=\frac Qt\implies t=\frac QP=\frac{Lm}{P}=\frac{2.26\cdot 10^6\cdot 0.5}{2200}=8.5~min.$

4.

$Q=\lambda m=3.34\cdot 10^5\cdot 0.3=0.1~MJ.$

5.

The difference in the transition to the liquid and gaseous phase, respectively.