Question
Calculate the energy required to change the temperature of 256.7 mL of water at 22.0 degrees celsius to ice at a temperature of -25.5 degrees celsius.
It also tells me to look up the heat of fusion and specific heat. I don't know what I need the heat of fusion for exactly. Please help!
It also tells me to look up the heat of fusion and specific heat. I don't know what I need the heat of fusion for exactly. Please help!
Answers
The question is worded funny. You don't need energy "required" since moving T from 22 C to ice at minus whatever removes heat, not adds heat. Anyway,
q1 = heat removed to change T of liquid water @ 22 C to liquid water at zero C.
q1 = mass H2O x specific heat liquid water x (Tfinal-Tinitial)
q2 = heat removed to change liquid water at zero C to solid at zero C. This is why you need the heat of fusion.
q2 = mass H2O x heat fusion.
q3 = heat removed to change T of ice at zero C to -25.5 C.
q = mass ice x specific heat solid ice x (Tfinal-Tinitial)
Total energy removed is q1 + q2 + q3.
q1 = heat removed to change T of liquid water @ 22 C to liquid water at zero C.
q1 = mass H2O x specific heat liquid water x (Tfinal-Tinitial)
q2 = heat removed to change liquid water at zero C to solid at zero C. This is why you need the heat of fusion.
q2 = mass H2O x heat fusion.
q3 = heat removed to change T of ice at zero C to -25.5 C.
q = mass ice x specific heat solid ice x (Tfinal-Tinitial)
Total energy removed is q1 + q2 + q3.
The mass of the ice should be the same as the mass of the H2O right?
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