Question #5db77

1 Answer
Sep 13, 2017

Here's how you can do that.


The problem wants you to go from joules per gram to kilojoules per mole, so right from the start, you know that you're going to need two conversion factors.

The first one will take you from joules to kilojoules

#color(blue)(ul(color(black)("1 kJ" = 10^3color(white)(.)"J")))#

and the second one will take you from grams to moles

#color(blue)(ul(color(black)("1 mole H"_2"O" = "18.015 g")))" " -># the molar mass of water

Set up the calculation as

#3.34 * 10^2 color(red)(cancel(color(black)("J")))/(1color(red)(cancel(color(black)("g")))) * "1 kJ"/(10^3color(red)(cancel(color(black)("J")))) * (18.015color(red)(cancel(color(black)("g"))))/("1 mole H"_2"O") = color(darkgreen)(ul(color(black)("6.02 kJ mol"^(-1))))#

The answer is rounded to three sig figs.