Question

How much energy (in KJ) is needed to melt 15g of ice at -4oC and raise it to a temperature of 115oC? Round the closest number, and include units

Answer 1

Answer:

The energy needed is 45.7659 kJ

Explanation:

The given mass of the ice, m = 15 g

The initial temperature of the ice, T₁ = -4°C

The temperature

The final temperature, T₂ = 115°C

The specific heat capacity of ice, c₁ = 2.09 J/(g·°C)

The latent heat of ice, l₁ = 334 J/g

The heat capacity of water, c₂ = 4.184 J/(g·°C)

The latent heat of vaporization, l₂ = 2260 J/g

The specific heat of steam, c₃ = 2.02 J/g

Therefore, we get the energy needed, ΔQ, as follows;

ΔQ = m·c₁·(T₂ - Tₐ) + m·l₁ + m·c₂(Tₓ - Tₐ) + m·l₂ + m·c₃·(T₂ - Tₓ)

Where;

Tₐ = The melting point temperature of water = 0°C

Tₓ = The boiling point temperature of water = 100°C

∴ ΔQ = 15×2.09×(0 - (-4)) + 15 × 334 + 15×4.184×(100 - 0) + 15×2260 + 15×2.02×(115 - 100) = 45,765.9

The energy needed, ΔQ = 45,765.9 J = 45.7659 kJ.