@crumlev,
crumlev wrote:
aren't we concerned with the partial pressure of the water vapor over the liquid? is, bp is reached when the pressure of the water is equal to the pressure of the water vapor above it? In that case the lid would affect the bp to the degree that it traps the water vapor inside.
Well, that's why a pressure cooker cooks things faster; it increases the pressure inside the vessel so that water boils at a higher temperature and the food cooks faster.
But unless the lid is pressure sealed, the effect is going to be minimal. How much does an aluminum lid weigh, over what area? It's not going to increase the pressure very much.
