Question #2a6cb

1 Answer
Apr 27, 2015

You have to do 5 different calculations for this, and you need to know 5 different thermodynamic constants.

1st - heat ice from #-5^@"C"# to #0^@"C"#
2nd - melt ice at #0^@"C"#
3rd - warm water from #0^@"C"# to #100^@"C"#
4th - vaporize water to steam at #100^@"C"#
5th - heat steam from #100^@"C"# to #115^@"C"#

1st.
#"heat" = "75 g" * 2.09J/("g" * ^@"C") * 5^@"C" = "0.784 kJ"#

2nd
#"heat" = "75 g"/(18"g"/"mol") * (6.01"kJ"/"mole") = "25.04 kJ"#

3rd
#"heat" = "75 g" * 4.184 "J"/("g" * ^@"C") * 100^@"C" = "31.38 kJ"#

4th
#"heat" = "75 g"/(18"g"/"mol") * 40.79 "kJ"/"mole" = "169.9 kJ"#

5th
#"heat" = "75 g" * 1.85 "J"/("g" * ^@"C") * 15^@"C" = "2.08 kJ"#

And to get the total heat, you add them all up.
About #"229.2 kJ"#.