Principle

In this experiment, the pupils are to find out through their own measurements that the resulting mixture temperature is not only the result of the temperature of the two mixing partners, but also depends on the mixing ratio. When mixing hot and cold water, a mixing temperature is reached after a short time. This depends on the temperature of the mixing partners as well as on their ratio. The students investigate the following questions:

• What is the mixing temperature if the amounts of cold and hot water are equal? When equal amounts of hot and cold water are poured together, the mixing temperature is halfway between the two temperatures. The mixing temperature is the average of the temperature of the hot water and the temperature of the cold water.
• How does the mixture temperature change when there is more hot water than cold water in the beaker? When there is more hot water than cold water in the beaker, the mixture temperature is greater than the average.
• What is the temperature when the amounts of hot and cold water are exactly reversed? If there is more cold water than hot water in the beaker, then the mixing temperature is less than the mean. As the comparison of the 2nd and 4th experiment shows, the mixing temperatures deviate from the mean value by the same amount.