A 115-g sample of steam at 100 °C is emitted from a volcano. It condenses, cools, and falls as snow at 0.0 °C. How many kilojoules were released? (3.6, 3.7)

Answer 1

step 1: find heat released going from steam @100º to liquid @100º (phase change)

step 2: find heat released going from 100º to 0º

step 3: find heat released from from liquid @ 0º to solid @0º (phase change)

step 1: q = m∆Hvap = (115 g)(2260 J/g) = 259,900 J

step 2: q = mC∆T = (115 g)(4.184 J/gº)(100º) = 48,116 J

step 3: q = m∆Hfus =(115 g)(334 J/g) = 38,410 J

Total = 259,900 J + 48,116 J + 38,410 J = 346,426 J x 1 kJ/1000 J = 346 kJ