Savannah Mance 4G
Posts: 107
Joined: Fri Aug 30, 2019 12:17 am

In 4C.13 why do you add enthalpy to the heat supply of the ice??? I understand why the heat gained by the ice is equal to the heat lost by the water. But, I don't get why the change in enthalpy is being added to the head gained by the ice.

Sebastian Lee 1L
Posts: 157
Joined: Fri Aug 09, 2019 12:15 am
Been upvoted: 1 time

In this problem, you need to find equations for both the heat change of the ice and the water to find the final temperature. The heat change (q) of the ice involves both the enthalpy of fusion (what you're confused about) and the heat needed to increase the temperature of the melted ice. $\Delta H_{fus}$ is necessary because you need to account for the amount of heat required to melt the ice into liquid water. The heat absorbed by the water is equal to $\Delta H_{fus} + mc\Delta T$ because the heat first melts the ice and then warms up the water. Of course, you'll need to convert the enthalpy per mole to the correct amount for the problem.