2. Which is NOT a chemical change?
a. a piece of wood is burned b. an egg is cooked
c. a bar of iron rusts d. ingredients for a cake are stirred together

3. Samples of gases containing nitrogen and oxygen were decomposed by electricity and the volume of each gas
produced was measured. Based on these results, what is the correct chemical formula for Sample 4?
Sample
Volume of Nitrogen (L)
Volume of Oxygen (L) 1
2.00
3.02 2
1.01
1.99 3
1.98
4.99 4
1.02

4. The law of ____ states that a compound is always composed of the same elements in the same proportion by
mass.

5. Which of the following substances is a mixture?
a. Baking soda b. Gasoline
c. Salt d. Sugar

6. Matter that has a uniform and unchanging composition is known as a(n) ____.

7. What is the state of matter that has a definite shape and definite volume?

8. Which is an intensive physical property?
a. color b. mass
c. length d. volume

9. Which is a compound?
a. sodium b. sea water
c. carbon dioxide d. brass

10. How many individual atoms make up one unit of aluminum chloride, AlCl3?

11. A chemical composition of two or more different elements joined together in fixed proportions is known as a(n)
____.

12. What is the separation technique that identifies parts of a mixture based on how fast different compounds
move across a material?

13. Which of the following formations is a physical property of copper?
a. A deep blue solution when in contact with ammonia.
b. A new substance when combined with nitric acid.
c. A green copper carbonate compound when in contact with moist air.
d. A formation of a drill gauge and wire.

14. What is the state of matter that has an indefinite shape and indefinite volume?

15. Identify both a physical change and a chemical change that could be done to a piece of fruit.

16. If 26 grams of potassium are burned in air to produce 12
If 26 grams of potassium are burned in air to produce 12.2 grams of potassium oxide, what is the mass of oxygen
from the air that is needed?

17. Is a solution a homogeneous or heterogeneous mixture?

18. A 20-g sample of magnesium reacts with bromine to form 32 g of magnesium chloride. How many grams of chlorine
are used in the reaction?

19. What is the percentage by mass of oxygen if 6
What is the percentage by mass of oxygen if 6.23 g of it reacts with g of nitrogen to form a compound of mass g? Also, calculate the percentage by mass of nitrogen in the compound.

20. Copper sulfide is formed when copper and sulfur are heated together
Copper sulfide is formed when copper and sulfur are heated together. In this reaction, 152 g of copper reacts
with 55 g of sulfur. After the reaction is completed, 8 g of sulfur remains unreacted. What is the mass of
copper sulfide formed?

21. A 25. 3 g sample of an unknown compound contains 0. 8 g of oxygen
A 25.3 g sample of an unknown compound contains 0.8 g of oxygen. What is the percent by mass of oxygen in the compound?