|
|
|||||||||||||||||||||||||||
  |
|||||||||||||||||||||||||||
HEAT AND COLD
What are heat and cold? It's a pretty simple idea. You think of heat, you think of fire. You think of cold, you think of an ice cube. It all has to do with kinetic energy. Heat has a lot of kinetic energy and gives it away. The cold doesn't have much and absorbs energy from the area. Scientists measure heat in units called Joules.
THERMOCHEMISTRYThere are two kinds of heat in chemistry. The first is caused by physical activity. As you get more kinetic energy, there is more activity in the system. This extra activity makes more molecular collisions occur. The collisions create the heat (such as when you increase the pressure in a system). Chemical processes cause the second type of heat. Instead of exciting a system and feeling the heat, chemical bonds are made and broken, and the energy is then released. A release of energy charges up the system and the molecules bounce around faster, resulting in that physical activity we just explained. The opposite can also happen. Sometimes bonds are made and broken and energy is absorbed. The area then gets colder.
There is energy all around us. Just as matter is all around us, energy is always there. Usually you will feel this energy as heat. Let's say it's really hot out today. Why is it hot? One big reason is that there is a lot of heat/energy coming from the Sun. The sun is a big furnace and that furnace heats the Earth. When a lot of the sun's radiant energy makes it to Earth, it transmits energy to the atoms and molecules in the air and ground. Those molecules heat up. The Sun makes your molecules more excited because of the energy hitting you.
ENERGY IN CHEMICAL BONDSHow about when you burn a piece of wood? When you burn something, you release the energy from the chemical bonds in the wood. Where did the energy come from? The Sun. A plant needs the sun to grow. Light hits the plant and helps a process called photosynthesis. The plant captures the energy and stores it in the chemical bonds. When you burn a piece of wood, you are releasing all of the energy stored up, and that energy is heat.
|
Custom Search
* The custom search only looks at Rader's sites. 
|
||||||||||||||||||||||||||
 
Go for site help or a list of chemistry topics at the site map!©copyright 1997-2009 Andrew Rader Studios, All rights reserved. Current Page: Chem4Kids.com | Reactions | Thermodynamics |
|||||||||||||||||||||||||||
|
|
|||||||||||||||||||||||||||