8.19

[Maeve Gallagher 1J]

Calculate the heat that must be supplied to a 500.0-g copper kettle containing 400.0 g of water to raise its temperature from 22.0 'C to the boiling point of water, 100.0 'C.

Why does the solutions manual have you add the q of the copper and the q of the water instead of setting q copper = -q water as it does for other similar problems?

[Rana YT 2L]

the q values for the water and the copper are added in the solution manual because no heat is technically being lost. Instead, heat is simply being transferred into the kettle and then into the water. Because of this, there is no loss in heat in either kettle nor the copper, meaning that no negative is necessary

[Wenting Hu 2H]

For q(copper)= - q(water), does it matter where the negative sign is? I learned today in discussion that it did but then it doesn't make sense to me. Isn't the water gaining the heat that the copper lost? So shouldn't it be -q(copper)=q(water)?