Chapter 7.2 Using energy transfers from reactions

Question 1

What is the reaction used to transfer energy to the food or drink?

Answer 1

Calcium oxide + Water ==> Calcium hydroxide

Question 2

Where are exothermic changes used in?

Answer 2

Exothermic changes are used in hand warmers and self-heating cans.

Question 3

What can endothermic processes be used for? and give an example

Answer 3

Endothermic processes can be used to cool things down. For example, chemical cold packs usually contain ammonium nitrate and water. When ammonium nitrate dissolves, it absorbs energy from its surroundings, making them colder.

Question 4

Where are endothermic changes used in?

Answer 4

Endothermic changes can be used in instant cold packs for sports injuries to minimise damage.

Question 5

How do reusable hand warmers work?

Answer 5

The other type of chemical hand warmer relies on crystallisation of a supersaturated solution. As the sodium acetate crystallises, heat is released (up to 130 degrees Fahrenheit). The product can be recharged by heating the pad in boiling water, which dissolves the crystals back into the small amount of water.