Question

Thermochemistry?

Answer 1

Heat to evaporate 10 grams HOH = 5400 calories = 22,600 joules

Explanation:

The phase change energy of water can be calculated using
`Q = m DeltaH_(transition)` where `m` is mass and `DeltaH_(transition)` is the transition constant per unit mass of water. For evaporation or condensation the constant is Heat of Vaporization `DeltaH_(v) = 540 ("calories")/(gram)` and for freezing or melting the constant is Heat of Fusion `DeltaH_f = 80 "calories"/"gram".` To convert to Joules, use the relationship 4.184 joules = 1 calorie.