Question

How many joules are released when 30.0 g of H2O(g) condenses at 100°C and cools to 10°C

Answer 1

Heat released : 79086 J

Further explanation

Condenses :

1. phase change (gas - liquid) : heat of vaporization (ΔH vap for water = 2260 J/g)

2. cools from 100 - 10 : (Q=m.cΔT)

1. Q=m.ΔH vap

`\tt Q=30* 2260=67800~J`

2. Q=mc.ΔT(c water = 4.18 J/g C)

`\tt Q=30* 4.18* (100-10)\\\\Q=11286~J`

Q tot = 67800 + 11286 = 79086 J