Question

12. In a calorimeter, 10 g of ice absorbs heat with an enthalpy of fusion of 334 J/g. What is the heat absorbed?
q = mCHf

I am having a lot of trouble on this type of problem in chem. Help and an explanation would be greatly appreciated. Thank you.

Answer 1

When you are moving within a phase (for example, liquid water at one T to liquid water at another T OR ice at one T to ice at another T OR steam at one T to steam at another T), the equation to use is
q = mass x specific heat of the substance in that phase x (Tfinal-Tintial).

When you are at the phase change point (ice or liquid water at zero C) the formula is
q = mass x heat fusion. + if ice to liquid or - if liquid to solid.

When you are at the phase change point at the other end (liquid water or steam at 100 C) the formula is
q = mass x heat vaporization. + if liquid to steam or - if steam to liquid.

In the problem above it is
q = mass x heat fusion
q = 10 g x 334 J/g = 3340 J. Since the ice is absorbing heat it is + 334 J.

Answer 2

Thanks so much DrBob222. This helped a bunch!