Chapter 3: review problems and questions
1.
A 3.5 kg iron shovel is left outside through the winter. The shovel, now orange with rust, is
rediscovered in the spring. Its mass is 3.7 kg. How much oxygen combined with the iron?
0.2kg
2. When 5.0g of tin reacts with hydrochloric acid, the mass of the products, tin chloride and
hydrogen, totals 8.1g. How many grams of hydrochloric acid were used?
3.1g
3. A compound is analyzed and found to be 50.0% sulfur and 50.0 % oxygen. If the total amount of
the sulfur oxide compound is 12.5g, how many grams of sulfur are there?
6.25g
4. Two unknown compounds are analyzed. Compound I contains 5.63g of tin and 3.37g of
chlorine, while compound II contains 2.5g of tin and 2.98g of chlorine. Are the compounds the
same?
No
Compound I: tin = 62.5%, Cl = 37.4%
Compound II: tin = 45.6%, Cl = 54.4%
5. Classify each as a chemical or physical change:
a. Crushing an aluminum can ____physical__________________
b. Recycling used aluminum cans to make new ones ________physical______________
c. Aluminum combining with oxygen to form aluminum oxide ______chemical_____________
6. What is the percent by mass of 20.00g of granulated sugar containing 8.44g carbon, 1.30g
hydrogen and 10.26 g oxygen?
C = 42.2%, H = 6.5%, O = 51.3%
7. Carbon reacts with oxygen to form two different compounds. Compound I contains 4.82 g of
carbon for every 6.44g of oxygen. Compound II contains 20.13g of carbon for every 53.7g of
oxygen. What is the ratio of carbon to a fixed mass of oxygen for the two compounds?
2:1
8. Classify each as homogeneous or heterogeneous:
a. Brass _______homogeneous_________________
b. A salad ________heterogeneous____________
c. Blood ________heterogeneous_____________
d. Iced tea _______homogeneous___________
9. Describe a method to separate the following mixtures.
a. Muddy water _________filter (particle sizes)________________
b. Leaf pigments ______chromatography (solubility)___________________
c. A mixture of ethanol, boiling point = 78oC, and water, boiling point = 100oC
_________distillation (boiling points)_____________