An unknown volume of water at 18.2°C is added to 24.4 mL of water at 35.0°C. If final T is 23.5°C, what was the unknown volume

An unknown volume of water at 18.2°C is added to 24.4 mL of water at 35.0°C. If the final temperature is 23.5°C, what was the unknown volume? (Assume that no heat is lost to the surroundings; d of water = 1.00 g/mL.)

also why did the problem give me the density? i have seen in alot of other problems like specific heat and others that give me the density. What should I be doing with that number? thanks. I know d=Molarmass x Pressure /RT or m/V

This a calorimetry problem, the energy released by the 24.4 mL (or g) of water going from 35.0oC to 23.5oC equals the energy absorbed by the unknown mass of water going from 18.2oC to 23.5oC, but opposite in sign.

E = C m ?T

Ereleased = 4.18 J/oC g * 24.4 g * (23.5oC - 35.0oC)

Eabsorbed = 4.18 J/oC g * unk g * (23.5oC - 18.2oC)   

Solve for the unk mass of water, volume in mL.

I think(?)

Otis