If the heat of fusion for ethyl alcohol is 26 cal/g, how many grams must freeze to release 780 cal?
26 cal/g x ??g = 780 cal
30
To answer this question, we can use the formula:
Q = m * ΔH
where:
Q is the amount of heat released (in cal),
m is the mass of the substance that freezes (in g), and
ΔH is the heat of fusion (in cal/g).
We are given:
ΔH = 26 cal/g
Q = 780 cal
We need to find the mass, m.
Rearranging the formula gives us:
m = Q / ΔH
Substituting the given values:
m = 780 cal / 26 cal/g
Calculating the value:
m = 30 g
Therefore, 30 grams of ethyl alcohol must freeze to release 780 calories of heat.