1. A large slab of concrete, 5 × 8 × 0.3 m, is used as a thermal storage mass in a solar-heated house. If the slab cools overnight from 23?C to 18?C in an 18?C house, what is the net entropy change associated with this process?
2. A foundry form box with 25 kg of 200?C hot sand is dumped into a bucket with 50 L water at 15?C. Assuming no heat transfer with the surroundings and no boiling away of liquid water, calculate the net entropy change for the mass.