If you were given the choice of using substance A or B in this experiment, which
ID: 2104877 • Letter: I
Question
If you were given the choice of using substance A or B in this experiment, which would you choose? Why?
Given that:
If a substance (substance A) has a latent heat of vaporization of 250 J/g, how
much energy (heat) is required to evaporate 5 grams?
L is latent heat (J/g) and g is grams of substance.
Lg = (J/g) x g = Energy (J)
E = 250 J/g x 5 g = 1,250 J is required
If heat is being provided only by a resistor with a power output of 50 Watts, how long will it take to evaporate the 5 grams? (show all your work for both parts)
50 W = 50 J/s. 1,250 J of energy is required to evaporate 5 grams, which takes, t = J/(J/s) = 1,250 J/50 J/s = 25 s
Repeat the calculations for question (2), but with a substance (substance B)
with latent heat of vaporization of 2500 J/g.
E = Lg = 2,500 J/g x 5 g = 12,500 J is required
t = J/W = J/(J/s) = 12,500/50 = 250 s
Explanation / Answer
substance A
there are two reasons
1. it requires less amount of energy to evaporate
2. it takes less time to evaporate