# Question #fc739

##### 1 Answer

#### Explanation:

In order to be able to answer this question, you must know the value of the **enthalpy of fusion** of water

#DeltaH_"fus" = "333.55 J g"^(-1)#

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

Now, the enthalpy of fusion tells you the amount of heat needed in order to melt

In your case, you know that in order to convert

Since you know that

#"1 kJ" = 10^3color(white)(.)"J" " "# and#" " "1 kg" = 10^3color(white)(.)"g"#

you can convert the enthalpy of fusion from *joules per gram* to *kilojoules per kilogram*

#DeltaH_"vap" = (333.55 color(red)(cancel(color(black)("g"))))/(1color(red)(cancel(color(black)("J")))) * (color(blue)(cancel(color(black)(10^3))) color(red)(cancel(color(black)("J"))))/"1 kJ" * "1 kg"/(color(blue)(cancel(color(black)(10^3)))color(red)(cancel(color(black)("g")))) = "333.55 kJ kg"^(-1)#

So, you know that you need

This means that your sample will require

#6.00 color(red)(cancel(color(black)("kg"))) * "333.55 kJ"/(1color(red)(cancel(color(black)("kg")))) = color(darkgreen)(ul(color(black)(2.00 * 10^(3)color(white)(.)"kJ")))#

The answer is rounded to three **sig figs**, the number of sig figs you have for your sample.

You can thus say that the change in enthalpy that accompanies the conversion of

#DeltaH_ "fus for 6 kg ice" = +2.00 * 10^3color(white)(.)"kJ"#

The value must bepositivebecause the heat is beingabsorbedby the ice.