# chemistry

How do you calculate the energy change required to take 45g of water vapor at 126 degrees C to ice at -25degrees C?

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1. This is long but it is simple.
q1 = heat removed from vapor at 126 C to vapor at 100 C.
q1 = mass x specific heat steam x (126-100)

q2 = heat removed to condense steam at 100 to liquid water at 100 C.
q2 = mass x delta Hvap

q3 = heat removed to move T from 100 to 0.
q3 = mass x specific heat water x (100-0).

q4 = heat removed to freeze water.
q4 = mass x heat fusion.

q5 = heat removed to move T from 0 to -25 C.
q5 = mass x specific heat ice x 25

total Q = q1 + q2 + q3 + q4 + q5

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