What will be the final temperature if 500 cm

3 of water at 0 °C is added to 200cm

3 of water at 90 °C? [Density of water = 1gcm

-3]

**Answer**:

The density of water is 1g/cm3, which means the mass of 1 cm3 of water is equal to 1g.

Let the final temperature = θ

m1 = 500g = 0.5kg

c1 = c

θ1 = θ - 0 = θ

m2 = 200g = 0.2kg

c2 = c

θ2 = 90 - θ

m1c1θ1 = m2c2θ2

(0.5) c ( θ ) = (0.2) c ( 90 - θ )

0.5 θ = 18 - 0.2 θ

0.5 θ + 0.2 θ = 18

0.7 θ = 18

θ = 25.71 oC