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Test Review
Classify the following as being a physical or chemical change.
1. __________Sodium hydroxide dissolves in water.
2. __________Hydrochloric acid reacts with potassium hydroxide to produce a salt,
water and heat.
3. __________A pellet of sodium is sliced in two.
4. __________Water is heated and changed to steam.
5. __________Potassium chlorate decomposes to potassium chloride and oxygen gas.
6. __________When placed in water, a sodium pellet catches on fire as hydrogen gas
is released and sodium hydroxide forms.
7. __________Evaporation
8. __________Ice melting
9. __________Milk sours
10. __________Sugar dissolves in water.
11. __________Wood rotting.
12. __________Grass growing in a lawn.
13. __________An Alka-Seltzer tablet releasing carbon dioxide gas when coming in
contact with your stomach acid.
14. __________Water is absorbed by a paper towel.
15. __________Food is digested in the stomach.
Identify the following as being true or false to the left of the sentence. If the
statement is false, explain why it is false.
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A change in size or shape is a physical change.
A chemical change means a new substance with new properties was formed.
An example of a chemical change is when water freezes.
When platinum is heated, then cooled to its original state, we say this is a
physical change.
20. When milk turns sour, this is a physical change because a change in odor
does not indicate a chemical change.
21. When citric acid and baking soda mix, carbon dioxide is produced and the
temperature decreases. This must be a chemical change.
22. Chemical bonds break during a physical change.
23. Chemistry is the study of matter and how matter changes.
24. After burning for three hours, a candle has lost half of its mass. Explain why this
example does not violate the law of conservation of mass.
25. Explain how ice melting can demonstrate the law of conservation of mass.
26. Explain the difference between an exothermic and an endothermic reaction. Give
examples in your answer.
27. Explain the difference between mass, weight, and matter.