Question

What minimum heat is needed to bring 150 g of water at 50 ∘C to the boiling point and completely boil it away? The specific heat of water is 4190 J/(kg⋅K) and its heat of vaporization is 22.6×105 J/kg.

Answer 1

To calculate the minimum heat required to bring 150 g of water at 50 ∘C to the boiling point and completely boil it away, use the formulas for heating and vaporizing water. The total minimum heat required is the sum of the two calculations.

Step-by-step explanation:

To calculate the minimum heat required to bring 150 g of water at 50 ∘C to the boiling point and completely boil it away, we need to consider two processes: heating the water to its boiling point and then vaporizing it.

First, to heat the water from 50 ∘C to 100 ∘C, we can use the formula: Q = m * c * ΔT, where Q is the heat, m is the mass of water, c is the specific heat, and ΔT is the change in temperature. Substituting the given values, we get: Q1 = 150 g * 4190 J/(kg⋅K) * (100 ∘C - 50 ∘C).

Next, to vaporize the water, we use the formula: Q = m * Hv, where Q is the heat, m is the mass of water, and Hv is the heat of vaporization. Substituting the given values, we get: Q2 = 150 g * 22.6×105 J/kg.

The total minimum heat required is the sum of Q1 and Q2.