What happens when you put dry baking powder in cold water and hot water?

When you put dry baking powder in cold water, it will dissolve slowly, releasing some carbon dioxide gas, but the reaction is minimal due to the lack of heat. In hot water, however, the chemical reaction occurs more rapidly, producing significant amounts of carbon dioxide gas and creating bubbles, which causes the mixture to fizz and rise. This difference in reaction rates is due to the increased energy in hot water, which accelerates the reaction between the baking powder's acid and base components. Overall, hot water enhances the leavening effect of baking powder.