Download Unit 6 Moles and Stoichiometry Short Answer Review

Unit 6 Moles and Stoichiometry Short Answer Review
Base your answers to questions 1 through 3 on the
information below.
Rust on an automobile door contains Fe 2O3(s). The
balanced equation representing one of the reactions
between iron in the door of the automobile and oxygen
in the atmosphere is given below.
4Fe(s) + 3O 2(g)
2Fe 2O3(s)
1. Write the IUPAC name for Fe 2O3.
2. Determine the gram-formula mass of the product of this
reaction.
3. Identify the type of chemical reaction represented by this
equation.
4. Determine the percent composition by mass of oxygen in the compound C6H12O6
5. A hydrated compound contains water molecules within
its crystal structure. The percent composition by mass of
water in the hydrated compound CaSO 4•2H 2O has an
accepted value of 20.9%. A student did an experiment
and determined that the percent composition by mass of
water in CaSO 4•2H 2O was 21.4%.
Calculate the percent error of the student's experimental
result. Your response must include both a correct
numerical setup and the calculated result.
8. Base your answer to the following question on the
information below.
A scientist in a chemistry laboratory determined the
molecular formulas for two compounds containing
nitrogen and oxygen to be NO2 and N2O5
In the space provided in your answer booklet, show a
correct numerical setup for calculating the percent
composition by mass of oxygen in NO 2.
_________________ %
6. Base your answer to the following question on the information below.
The decomposition of sodium azide, NaN 3(s), is used to inflate airbags. On impact, the NaN 3(s) is ignited
by an electrical spark, producing N2(g) and Na(s). The N2(g) inflates the airbag.
Balance the equation using the smallest whole-number coefficients.
7. Given the balanced equation:
4Al(s) + 3O 2(g)
2Al 2O3(s)
What is the total number of moles of O 2(g) that must
react completely with 8.0 moles of Al(s) in order to form
Al 2O3(s)?
9. Given the equation:
2 H2(g) + O 2(g)
2 H2O(g)
If 8.0 moles of O2 are completely consumed, what is the
total number of moles of H2O produced?
Unit 6 Moles and Stoichiometry Short Answer Review
Base your answers to questions 10 through 12 on the balanced chemical equation below.
2 H2O ® 2 H2 + O2
10. What is the total number of moles of O 2 produced when 8 moles of H 2O is completely consumed?
11. How does the balanced chemical equation show the Law of Conservation of Mass?
12. What type of reaction does this equation represent?
Answer Key
Unit 6 moles short answer Review
1.
iron(III) oxide
2.
160.g/mol.
3.
Examples: – synthesis
– redox – oxidation
4.
53.3%
5.
• Correct Numerical
Setup Examples:
––
×
100
––
× 100
• Calculated Result
Examples: –– 2% ; ––
2.4% ; –– 2.39%
6.
2 NaN 3(s)
2
Na(s) + 3 N2(g).
7.
6
8.
× 100
9.
16 or 16.0
10.
4
11.
Acceptable responses:
4 H and 2 O on both
sides; 4 H = 4 H and 2
O = 2 O; same
number of each
element on both sides.
12.
Acceptable responses:
decomposition;
analysis; redox;
endothermic;
electrolysis.