First, no phase change, so we just have to calculate

the amount of heat involved by the heat equation.

Q = mC_{p}ΔT -------------------------------------------------------------where ΔT = T_{f} - T_{i}

Water is the substance used to define heat capacity which was set to 1 cal/g/°C.

Putting everything into the equation, we get:

Q = 3.0 Kg x 1000 g/Kg x 1 cal/g/°C x (80.0 - 10.0) °C --------units and significant figures are important here.

= 3.0 ~~Kg~~ x 1000 ~~g~~/~~Kg~~ x 1 cal/~~g~~/~~°C~~ x (80.0 - 10.0) ~~°C~~ -----------only cal left.

= 210,000 cal

= 210 kcal 2 s.f.

Now convert to kJ

1 cal = 4.184 J

Q = 210 ~~kcal~~ x 4.184 kJ/~~kcal~~

= 878.64 kJ

= 880 kJ // answer --------------------------------------------------------2 s.f.

Dr. Jonathan Y.

Let's me know if you need further help.05/22/20