In a certain chemical process, a lab technician supplies 231 J of heat to a system. At the same time, 81.0 J of work is done on the system by its surroundings.

What is the increase in the internal energy of the system?

part b. You have 782 g of water at 13.0 C in a large insulated beaker.

How much-boiling water at 100 C must you add to this beaker so that the final temperature of the mixture will be 73 C? Express your answer in kilograms to three significant figures.