According to an accepted chemistry reference, the heat of vaporization of water is 540 calories per
gram. A student determined in the laboratory that
the heat of vaporization of water was 620 calories
per gram. The student's results had a percent error
of

14.8%

Step-by-step explanation:

Step 1: Given data

True value for the  heat of vaporization of water (ΔH°vap(T)): 540 cal/g

Experimental value for the  heat of vaporization of water (ΔH°vap(E)): 620 cal/g

Step 2: Calculate the experimental percent error

To determine the experimental percent error we will use the following expression.

%E = |ΔH°vap(T) - ΔH°vap(E)|/ΔH°vap(T) × 100%

%E = |540 cal/g - 620 cal/g|/540 cal/g × 100%

%E = 14.8%