Science heat question

Question

 A 1.9 kg piece of copper metal at 70.0°C is placed in water at 25.0°C. The final temperature of the water and copper was 26.8°C. How much water was there? (kg)

[ c_copper = 385 J/(kg°C), c_water = 4184 J/(kg°C) ]

Answer 1

The absolute value of the heat lost by the copper equals the absolute value of the heat gained by the water.

That is, |Heat Lost By Copper| = |Heat Gained By Water|.

With values given, construct:

(1.9 kg Cu)(385 J/kg • °C)(70 −26.8)°C = (w kg H₂O)(4184 J/kg • °C)(26.8 − 25)°C.

Simplify this last by multiplication on both sides to obtain 31600.8 J = 7531.2w J, which

gives w equal to 4.195984704 (kilograms of water) or roughly 4.2 kg H₂O.