How many joules of heat are required to melt a 55.0-g ice cube at 0°C?

1 Answer
Jul 15, 2016

Answer:

#"18,300 J"#

Explanation:

In order to be able to answer this question, you must know the value of water's enthalpy of fusion, #DeltaH_"fus"#, which is listed as

#DeltaH_"fus" = "33.55 J g"^(-1)#

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

Now, a substance's enthalpy of fusion tells you how much heat is needed in order to convert #"1 g"# of said substance from solid at its melting point to liquid at its melting point.

In water's case, an enthalpy of fusion equal to #"333.55 J g"^(-1)# tells you that #"1 g"# of ice at #0^@"C"# can be converted to #"1 g"# of liquid water at #0^@"C"# by supplying #"333.55 J"# of heat.

Your ice cube has a mass of #"55.0 g"#, which means that it will require

#55.0 color(red)(cancel(color(black)("g"))) * overbrace("333.55 J"/(1color(red)(cancel(color(black)("g")))))^(color(blue)( = DeltaH_"fus")) = "18,345.25 J"#

Rounded to three sig figs, the number of sig figs you have for the mass of the ice cube, the answer will be

#"heat needed" = color(green)(|bar(ul(color(white)(a/a)color(black)("18,300 J")color(white)(a/a)|)))#