kJ to grams? Thermodynamics?

Question

These are some pratice problems out of my book that are similiar to my homework problems online but they dont show work since they are even. Someone mind showing a example, really apperciate it.

How many grams of methane [CH4(g)] must be combusted to heat 1.20 kg of water from 23.0°C to 85.0°C, assuming 1.00E2% efficiency in heat transfer?

And

At one time, a common means of forming small quantities of oxygen gas in the laboratory was to heat KClO3:
2KClO3(s)--->2KCl(s)+3O2(g) H=-89.4kJ

For this reaction, calculate for the formation of the following:

a) 0.805 mol of O2
b)10.85g KCl

And


How many grams of methane [CH4(g)] must be combusted to heat 1.20 kg of water from 23.0°C to 85.0°C, assuming 1.00E2% efficiency in heat transfer?

Thanks Steve and on that first one. That is all the books gives me so your guess is as good as mine.

Answer 1

a) 0.805molO2 x -89.4kJ/3molO2 = -72.0kJ to three sig figs.

b) Atomic weights: K=39.1 Cl=35.5 KCl=74.6

10.85gKCl x 1molKCl/74.6gKCl x -89.4kJ/2molKCl = 13.0kJ

You don't give the heat of combustion of CH4, so I can't do that.