What mass (in grams) of hot water was added?

Question

Suppose you have 20.92 g of water, initially at 25.00 oC, in a perfectly insulated container. You then add water which is at 75.65 oC to the container until the combined sample of water has a temperature of 50.65 oC. What mass (in grams) of hot water was added? Do not include units (g) in your answer. The specific heat capacity of water is 4.184 J g-1 oC-1.

Answer 1

You let mh = mass of water at higher temp

Heat Loss = Heat Gain

mhC ( change in T ) = mlC ( change in T )

mh ( 4.184) ( 75.65 - 50.65 ) = ( 20.92 ) ( 4.184 ) ( 50.65 - 25 )

mh ( 104.6 ) = 2245

mh = 2245 / 104.6 =  21.46   ans.