Determine the total amount of heat, in joules, required to completely vaporize a 50.0-gram sample of at its boiling point at standard pressure.

In order to calculate the amount of energy required, we must first check the latent heat of vaporization of water from literature. The latent heat of vaporization of any substance is the amount of energy required per unit mass to convert that substance from a solid to a liquid. For water this is 2,260 J/g. We now use the formula:
Energy = mass * latent heat
Q = 50 * 2,260
Q = 113,000 J

113,000 Joules of heat energy are required.

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