chemistry homework question

Question

If you combine 270.0mL of water at 25.00 C and 100mL  of water at 95.00 C what is the final temperature of the mixture? Use 1.00 g/mL as the density of water.

Answer 1

q = mC∆T where q = heat, m = mass, C = specific heat and ∆T = change in temperature

Heat gained by cooler water = heat lost by hotter water

(270.0 g)(4.184 J/gº)(Tf - 25º) = (100 g)(4.184 J/gº)(95º - Tf) where Tf = final temperature

Since C (specific heat for water) appears on both sides, we can eliminate it and have...

(270 g)(Tf - 25) = (100 g)(95 - Tf)

270Tf - 6750 = 9500 - 100Tf

370Tf = 16,250

Tf = 43.9º = final temperature