What is the change in internal energy and work to be done in the following case:
1. A gas expands when 849 J of energy is added to it by heat. The expanding gas does 702 J of work on its surroundings. What is the overall change in the internal energy of the gas in Joules?
2. If the work done by the gas is 890.6 J, how much energy in Joules must have been added as heat in order to keep the internal energy at the end of the process equal to the initial internal energy?