“Hot ice” experiment
How to make hot ice at home
Have you ever seen how a salt heater works? You just press it - and the capsule with fluid heats up and turns solid! Strangely enough, this heater works by using ice - only hot ice.
- Be careful when working with heating devices.
- Observe safety rules when working with these substances: wear protective gloves, glasses and mask.
Warning! Only under adults supervision.
Reagents and equipment:
- baking soda (sodium bicarbonate, 77 g);
- 9% solution of acetic acid (662 ml);
- water (51 ml);
- hot plate;
- glass container;
Sprinkle baking soda into the saucepan and pour vinegar over it. Stir thoroughly. Put the resulting solution on the hot plate and evaporate until it turns dry, and try to break up the lumps of the resulting powder. Then put the powder in the glass container, add water and heat in a water bath until it dissolves completely. Move the resulting solution to the beaker and allow to cool. Touch with your finger. Observe the formation of crystals and the release of heat.
In the reaction of acetic acid and sodium bicarbonate, sodium acetate forms. It has a very interesting property–it dissolves in its own crystallized water when heated. A saturated solution forms, which when it cools is very unstable and crystallizes from any impact, for example the touch of a finger.
However, in our experiment we dried the sodium acetate out completely, so it was easier to calculate the amount of water needed. This is so crystal hydrate forms–a solid salt with water molecules in a crystal lattice. For every 100 g of sodium acetate, around 66 g of water is required.
NaHCO₃ + CH₃COOH = CH₃COONa + CO₂ + H₂O
CH₃COONa•3H₂O(solid) = CH₃COONa(solution)