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Physical Change - wire inside the bulb The tungsten wire is...

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Physical Change Any change of matter that does not change the type of atoms and molecules within the  matter is called a physical change . Water boiling is an example of a  physical change . When  water boils it is changing from a liquid state to a gaseous state. Chemists would represent  this process as follows: H 2 O (l)    H 2 O (g) Here (l) stands for liquid and the (g) stands for gas. As this is a physical change, the H 2 molecule does not change. Chemical Change Molecules, on the other hand, can split or combine together to make other types of  molecules. The process where a molecule is transformed into a different molecule is called  chemical change . To help us understand the concept of chemical change let's examine why light bulbs are  made the way they are. A lightbulb works by passing electrical current through a tungsten 
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Unformatted text preview: wire inside the bulb. The tungsten wire is sealed inside a glass bulb since if you did this in air the light bulb would burn out very quickly. This is because the tungsten wire undergoes a chemical reaction with the O 2 gas in the air to form tungsten oxide. 2W + 3O 2 → 2WO 3 To prevent this reaction from happening, all oxygen is removed from the air sealed inside the bulb. If oxygen leaks into the bulb, then the tungsten wire reacts to become tungsten oxide and the oxidized wire will no longer pass electrical current readily. If you try to pass electrical current through the oxidized wire it will quickly heat up and break. That is, the lightbulb burns out ....
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