Question

A 102-g sample of an unknown liquid substance absorbed 59.5 kJ of heat to change to gas at its boiling point. What is the heat of vaporization of the unknown liquid?

Answer 1

Step 1

Latent heat is used to change a phase of a substance to another one.

Mathematically:

`Q\text{ = m x }\lambda`

Where,

Q = heat

m = mass of substance

λ = the heat of vaporization

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Step 2

Information provided:

Q = 59.5 J (a positive value because heat is absorbed)

m = 102 g

λ = unknown

Procedure:

Q = m x λ

Q/m = λ

59.5 J/102 g = 0.58 J/g

Answer: λ = 0.58 J/g