Science Essay

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Physical and chemical changes are everywhere, but these processes sometimes are so simple and common, that we may not even notice them. For example, if we cut an apple into two sections and ten minutes later observe what happens to the inside color, we will notice that it has become darker.


This burning of the wick and gaseous wax is an example of a chemical change.
Thus, a chemical change (or chemical reaction) is a change in which one kind of matter is changed into a different type of matter. Some other examples of chemical changes include the rusting of your car, setting your shoe on fire or digesting food. All of these materials combine chemically with another material , and cannot be separated by any physical means.
A physical change is a change in the form of matter but not in its identity. The dissolving of one thing into another thing is an illustrative. For instance, dissolving sugar into water. The water and the sugar retain their chemical identities and can be separated by physical means. One more example - ice melting to water. Ice and water are both H20. The identity of the matter is not changed, just the state that it is in. Remember: a physical change is when no new chemical substance is formed.
As it has already been mentioned, a chemical reaction occurs when two or more chemical substances are mixed together and change into new substances. For this to happen, the bonds between atoms and molecules must break up and then re-form in different ways. Because the bonds can be strong, energy (usually in the form of heat), is often needed to start a reaction.
The new substances (products) have different properties from those of the original substances (reactants). ...
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