Question

. A small puddle is frozen and its temperature is 0 oC. How much solar energy is needed to melt 10 kg of ice? Now assume that the ice is originally at -20 oC, then how much energy is needed this time?

Answer 1

Answer:

3758 kJ

Explanation:

Given:

Mass of the ice = 10 kg = 10 × 1000 = 10,000 g

Initial temperature of the ice = -20° C

Now,

The ice will start to melt when it will reach a temperature of 0° C

and, specific heat of ice, C = 2090 J/kg

Therefore,

Heat required to heat the ice from -20° C to 0° C

Q₁ = mCΔT

or

Q₁ = 10 × 2090 × (0 - (-20 ))

or

Q₁ = 418000 J

also,

Heat of fusion required to change the ice into liquid without any change in temperature.

For ice the heat of fusion = 334 J/g

Hence,

Energy needed by ice to melt, Q₂ = 334 × 10,000 J = 3,340,000 J

Hence, the total heat required = Q₁ + Q₂

= 418000 J + 3,340,000 J

= 3758000 J

= 3758 kJ