Classical experiment in chemistry – endothermic reactions.
Equipment
- Three cups, water, salt, baking soda, spoon.
Activities
Pour the water into three cups and point the thermal camera at them. Then sprinkle a spoonful of salt into the first, sprinkle a spoonful of baking soda into the second and observe temperature changes.
Questions for discussion
How will the cups change their temperatures? Why is it happening? Which substance needs more heat to dissolve?
Answer
The cups with salt and soda are cooled, because the dissolution of both substances requires energy, which is obtained by releasing heat from the water and this results in a drop in its temperature. Such events are called endothermic. Based on the measured temperatures, we find that soda consumed the most heat to dissolve it. The energy required to dissolve 1 gram of salt is 66 J, it takes approximately three times more energy to dissolve the same amount of baking soda, 222 J.