Question

Zoe has 25 grams of water (c = 4.186 ) at 10°C, which she mixes with 12 grams of water at 30°C. Assume that no heat is lost to the surroundings. What is the final temperature of the two liquids? The answer is expressed to the nearest whole number.

Answer 1

T = 16.49 degrees Celsius

Answer 2

Since heat here is conserved that means that the heat out is equal to the heat in. We use the expression Q = mC(T2-T1). We caclulate as follows:

Q absorbed = Q released
m1 C (T-T1) = -m2 C (T-T1)

C can be cancelled since they are the same substance.

m1 (T-T1) = -m2 (T-T1)
25 (T-10) = -12 (T-30)
T = 16.49 degrees Celsius