How many joules of heat are absorbed when 70.0 g of water is completely vaporised at its boiling point ?

Question

How many joules of heat are absorbed when 70.0 g of water is completely vaporised at its boiling point ? (A) 23,352 (B) 7,000 (C) 15,813 (D) 158,130

Tardigrade Admin · Accepted Answer

Since the process involves phase change, heat absorbed, Q= mass × latent heat of vaporisation Given, mass =70.0 g =0.07 kg Lv=2260 kJ / kg ∴ Q=0.07 × 2260 kJ =158.2 kJ =158200 J .

Q. How many joules of heat are absorbed when $70.0 g$ of water is completely vaporised at its boiling point ?

23,352

7,000

15,813

158,130

Since the process involves phase change, heat absorbed,

$Q =$ mass $\times$ latent heat of vaporisation

Given, mass $= 70.0 g = 0.07 k g$

$L_{v} = 2260 k J / k g$

$∴ Q = 0.07 \times 2260 k J$

$= 158.2 k J$

$= 158200 J .$

Q. How many joules of heat are absorbed when 70.0g of water is completely vaporised at its boiling point ?