Question

What will be the final temperature of a system in which 150.0 g of water at 5.0°C are added to 1.00 L of water at 90.5°C?

Answer 1

Here's a problem with an identical mathematical method of solution:

150 people, each of whom have $5, get together with 1000 people, each of whom have $90.50. They decide to pool the money and give everyone an equal share. With how much money does each person end up?

If you can solve that problem, you can also solve yours. The essential concept is "share equally." In the money problem, each person shares in an equal amount of the money. In the heat problem, each gram of water shares equally in the thermal energy per gram, which here is well-represented by the temperature.

It's generally important to break down the wall between chemistry problems and the problems you already know how to solve in your daily life, because a great deal of what you need to solve the former is present in the latter -- meaning you already know it.