The final temperature when 150 mL of water at 90.0 °C is added to 100.0 mL of water at 30.0 °C is around ________.
A)90 °C
B)120 °C
C)30 °C
D)70 °C
E)25 °C

Question

Quizplus · Accepted Answer

The final temperature can be found using the formula: 
(mass of hot water x change in temperature of hot water) + (mass of cold water x change in temperature of cold water) = 0 
Plugging in the values: 
(150 g x (final temperature - 90.0)) + (100 g x (final temperature - 30.0)) = 0 
Solving for final temperature gives us 70.0 °C, which is choice D.

The Final Temperature When 150 ML of Water at 90