If you combine 300.0 mL of water at 25.00 ∘C and 140.0 mL of water at 95.00 ∘C, what is the final temperature of the mixture? Use 1.00 g/mL as the density of water.

Explanation:

Hello!

In this case, since we have hot and cold water, we infer that as hot water cools down, cool water heats up based on the first law of thermodynamics; thus, we can write:

In such a way, we can write the expression in terms of mass, specific heat and temperature change:

However, since they both have the same specific heat and the same mL are in g due to the 1.00-g/mL density, we obtain:

Now, we plug in to obtain:

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