If 5 L of water at 50°C is mixed with 4L of water at 30°C, what will be the final temperature of water? Take the specific heat capacity of water as 4184 J kg-1K-1.
We can use the equation
m1 = 5L = 5kg and m2= 4L = 4kg, s1 = s2 and T1=50°C =323K and T2 = 30°C=303 K.
Tf = 314.11 K-273K ≈ 41°C.
Suppose if we mix equal amount of water (m1 = m2) with 50°C and 30°C, then the final temperature is average of two temperatures.
Suppose if both the water are at 30°C then the final temperature will also 30°C. It implies that they are at equilibrium and no heat exchange takes place between each other.