Gary Bower, age 12, of Williamsport, Penn
Why is fire hot?
We have all played the old guessing game called Animal, Mineral or Vegetable, You can put almost anything you choose in one of these three classes, But in which class would you put fire? We can see it, hear its feel it and it seems to be a thing. But it is not an animal not a mineral and certainly not a vegetable. Actually., we could call it an event, It belongs in the world of chemistry where it is called a chemical change.
The scientists tell us that everything around us is made of chemicals * even our own bodies. And chemicals are changeable. Two gases can be made to combine and become liquid water. This is a chemical change in which something new is built, We turn some of the chemicals in our food into energy. This is a chemical change in which something is broken down.
To make a cake# we mix ingredients and bake them, The mixture will not change into a cake without the heat of the oven. Heat is a form of energy and energy plays a part in every chemical change. A chemical change that builds something new usually uses up energy. A chemical change that breaks something apart usually gives off energy and very often this energy is in the form of heat,
Somewhere the green leaves are busy making plant sugar from sir and water. In this chemical change, they use the energy from sunlight. Some of the plant sugar is changed into wood and some of this wood finds its way to the fireplace, As it burns, certain chemicals in the wood are broken down.
Remembers the green leaves used water and gases from the d,r to make the chemicals which later became wood. When the wood burns.. it breaks down and becomes these very same chemicals again. But remember, the leaves also used the energy from sunlight. They used an oven to bake their chemical ingredients.
When the chemicals break apart in the fires this energy is set free, It becomes heat, In the hearth! a chemical change is taking plane, The complex chemicals in the wood are breaking apart into more simple chemicals, In the heat ih ich is set freei some of the gases blaze up in dancing flames,
The wood for the fireplace is fuel, Coal az d gas are also fuels axed so is the gasoline we put into a car, These fuels were made long ages ago but they too were made by green leaves from air, water and sunshine, Coal is the buried remains of ancient forests, Kitchen gas and gasoline is formed from the bodies of little sea dwellers who fed on scraps of ancient seaweeds, These fuels were put together by chemical changes and the energy used was stored within them through the ages, When they burn, they break apart and this chemical change releases their energy as heat,