Answer:
Explanation:
Start with physical processes.
Phase: if a chemical changes phase (going from solid to liquid or liquid to gas) , the chemical properties remain in tact. They may be harder to get but they are still there.
Color: sometimes there is a change in color. Chemical properties are more likely to change color, but a phase change can bring about a color change (eg hydrogen). The chemical properties are still there although dormant.
There is a term for the way sugar dissolves in water. I cannot find it. But it is an example of a physical change were heat is produced (very small) when sugar is added to water. If you were to boil the water off, the remaining solid (sugar) would have all the properties it had before being put into the water. No bonds have been broken, So the heat comes from a different form of reaction. And no real chemical reaction has taken place.
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Chemical properties: the main one is the breaking of bonds. When that happens, sometimes the reaction is reversible, sometimes not. A well known chemical reaction taking place in the laboratory is
NO2 - Heat ===> N2O4
which takes place in a sealed tube or a sealed peace of glass tubing.
When heat is added (this may go beyond what you know so just read the results) the equation goes to the left. NO2 is brownish red in color (more brown than red).
If heat is removed and the tube is put in ice water, the equation shifts to the right. N2O4 is colorless.
Result: the reaction is chemical. Bonds have been broken or reformed. This result is reversible. You can add or take away heat all day long and the general make up of what is in the tube remains unchanged even though bonds have been broken.
A more common chemical reaction is one like this one.
CH4 + 202 ===> CO2 + 2H2O
Once the methane (CH4) has been burned, the reaction can no longer go back to what it was. Bonds are broken. They stay broken.
If heat is taken away, more N2O4 is produced
