4C.13

[Nicole Ju 3H]

Is there a typo in the answer key for this problem?I keep getting 35 degrees celcius instead of 31.

Here is the equation I used:
q(gained) = -q(lost)
enthalpy of fusion (moles of H2O) = mc (delta T)
(6019 J/mol)(50.0g)(1 mol/18.02g) = -(400.0 g)(4.18 J/g C)(Tfinal -45)

[Kaitlin Eblen 1I]

Hi Nicole,
You're almost there! For the heat gained by the ice (the left side of your equation), you calculated the heat required for the ice cube's phase change from solid to liquid. However, you also need to account for the increase in temperature from 0 degrees Celsius to the final temp. The diagram should help explain why we need both. You can use q = mc*delta t in order to do this. Add that to the left side of your equation, solve for the final temp, and you should get 31!