A 0.4kg water at 10 degrees is poured into a beaker of 0.5kg of water at 90 degrees. What is the final temperature of the 0.9kg of water?

Answer 1

0.4 kg = 400 g

0.5 kg = 500 g

heat lost by warm water = heat gained by cold water

q = mCΔT where q=heat, m=mass; ΔT= change in temp

-(500g)(4.184 J/g/deg)(Tf-90) = (400g)(4.184 J/deg)(Tf-10)

4.184 is common so ignore it

-500Tf + 45,000 = 400Tf - 4000

900Tf = 49,400

Tf = 54.4 degrees