# 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

Otis

Wed, 2008-10-29 01:39

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## Re: Volume, Temperature, Unknown volume

This a calorimetry problem, the energy released by the 24.4 mL (or g) of water going from 35.0

^{o}C to 23.5^{o}C equals the energy absorbed by the unknown mass of water going from 18.2^{o}C to 23.5^{o}C, but opposite in sign.E = C m ?T

E

_{released}= 4.18 J/^{o}C g * 24.4 g * (23.5^{o}C - 35.0^{o}C)E

_{absorbed}= 4.18 J/^{o}C g * unk g * (23.5^{o}C - 18.2^{o}C)Solve for the unk mass of water, volume in mL.

I think(?)

Otis