Ch. 2 Chemical Reactions

3. The amount of one material in a certain volume of another material.
5. A system in which matter can enter from or escape to the surroundings.
9. A reaction that absorbs energy in the form of heat.
15. The minimum amount of energy needed to get a chemical reaction started.
16. A biological catalyst that lowers the activation energy of reactions in cells.
17. The study of the properties of matter and how matter changes.
18. A rapid reaction between oxygen and fuel that results in fire.
19. Anything that has mass and occupies space.
20. A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.
22. A chemical reaction that breaks down compounds into simpler products.

1. A reaction in which one element replaces another in a compound or when two elements in different compounds trade places.
2. A chemical reaction in which two or more simple substances combine to form a new, more complex substance.
3. A short, easy way to show a chemical reaction, using symbols.
4. A substance that enters into a chemical reaction.
6. A substance formed as a result of a chemical reaction.
7. A characteristic of a substance that can be observed without changing the substance into another substance.
8. A solid that forms from a solution during a chemical reaction.
9. A reaction that releases energy in the form of heat.
10. A characteristic of a substance that describes its ability to change into different substances.
11. The process in which substances undergo chemical changes that result in the formation of new substances.
12. A material that decreases the rate of a reaction.
13. A change that alters the form or appearance of a material but does not make the material into another substance.
14. A system in which no matter is allowed to enter or leave.
21. A material that releases energy when it burns.
23. A material that increases the rate of a reaction by lowering the activation energy.