It takes 80 cal/g to change solid water at 0°C to liquid water. How many calories will it take to change 3 g of water at 0 °C to liquid water?
The idea here is that the problem is providing you with a measure of how much heat is needed per gram of solid water, i.e. of ice, in order for a solid
Simply put, you are given a measure of how much heat is required to melt
So, you can say that
This means that
#3 color(red)(cancel(color(black)("g"))) * "80 cal"/(1color(red)(cancel(color(black)("g")))) = color(darkgreen)(ul(color(black)("240 cal")))#
I'll leave the answer rounded to two sig figs, but don't forget that you only have one significant figure for the mass of ice.
So remember this notation
#color(blue)("80 cal")color(red)("/g") " "=" " color(blue)("80 cal")color(white)(.)color(red)("g"^(-1))#
means that every