# Question 30924

Oct 29, 2016

Here's what I got.

#### Explanation:

In order to be able to answer this question, you need to know the enthalpy of fusion, $\Delta {H}_{\text{fus}}$, of water

$\Delta {H}_{\text{fus" = "333.55 J g}}^{- 1}$

https://en.wikipedia.org/wiki/Enthalpy_of_fusion

Now, the enthalpy of fusion is a measure of how much heat is needed to melt $\text{1 g}$ of ice at its melting point to liquid water at its melting point.

In other words, the enthalpy of fusion tells you how much heat is needed to make $\text{1 g}$ of ice undergo a solid $\to$ liquid phase change at ${0}^{\circ} \text{C}$.

In order to calculate the heat needed to melt $\text{51.0 g}$ of ice at its melting point, use the enthalpy of fusion as a conversion factor

51.0 color(red)(cancel(color(black)("g"))) * "333.55 J"/(1color(red)(cancel(color(black)("g")))) = "17011 J"#

Rounded to three sig figs and expressed in kilojoules, the answer will be

$\textcolor{g r e e n}{\overline{\underline{| \textcolor{w h i t e}{\frac{a}{a}} \textcolor{b l a c k}{\text{heat needed " = " 1.70 kJ}} \textcolor{w h i t e}{\frac{a}{a}} |}}}$