Question

Solve the following problem.

Specific latent heat of vaporization of water is 2.26 × 106 J/kg. Calculate the energy needed to change 5.0 g of water into steam at 100 ºC.

Answer 1

Given: L_vap = 2.26 × 10⁶ J/kg, m = 5g = 5 × 10^-3 kg
In this case, no temperature change takes place an only a change of state occurs.

To find: Heat required to convert water into steam.

Formula: Heat required = mL_vap 

Calculation: From formula,

Heat required = 5 × 10^-3 × 2.26 × 10⁶ 

= 11300 J

= 1.13 × 10⁴ J

Heat required to convert water into steam is 1.13 × 10⁴ J.