Chemistry II Test 2 Study Guide
Short Answer
1. How many representative particles are in 1.45 g of a molecular compound with a molar mass of 237 g?
2. Find the mass in grams of 3.10
10
molecules of F .
3. Find the number of moles of argon in 607 g of argon.
4. Find the mass, in grams, of 1.40
10
molecules of N .
5. What is the percent composition of NiO, if a sample of NiO with a mass of 41.9 g contains 33.1 g Ni and 8.8
g O?
6. What is the percent by mass of hydrogen in aspirin, C H O ?
7. Calculate the molecular formulas of the compounds having the following empirical formulas and molar
masses: C H , 58 g/mol; CH, 78 g/mol; and HgCl, 236.1 g/mol.
8. Complete and balance the following equation.
Al Cl
9. Complete and balance the following equation.
CH
O
CO
10. Complete and balance the following equation.
Fe (SO )
Ba(OH)
11. Balance the following equation. Indicate whether combustion is complete or incomplete.
C H
O
CO H O
12. Write a balanced net ionic equation for the following reaction.
H PO (aq) Ca(OH) (aq)
Ca (PO ) (aq) H O(l)
13. Complete and balance the following equation:
K PO
BaCl
14. If a total of 13.5 mol of NaHCO and 4.5 mol of C H O react, how many moles of CO and Na C H O
will be produced?
15. If 8.00 mol of NH reacted with 14.0 mol of O , how many moles of H O will be produced?
16. If 8.6 L of H reacted with 4.3 L of O at STP, what is the volume of the gaseous water collected (assuming
that none of it condenses)?
17. Assuming STP and a stoichiometric amount of NH and NO in an expandable container originally at 15 L,
what is the final volume if the reaction goes to completion?
NH (g) + NO(g)
N (g) + H O(g)
18. How many grams of CO are needed to react with an excess of Fe O to produce 209.7 g Fe?
Fe O (s) + CO(g) CO (g) + Fe(s)
19. How many liters of O are needed to react completely with 45.0 L of H S at STP?
2H S(g) + 3O (g)
2SO (g) + 2H O(g)
20. For the reaction 2Na(s) + Cl (g)
Na and 13.0 L of Cl (at STP)?
2NaCl(s), how many grams of NaCl could be produced from 103.0 g of
21. Solid sodium reacts violently with water, producing heat, hydrogen gas, and sodium hydroxide. How many
molecules of hydrogen gas are formed when 48.7 g of sodium are added to water?
Na + H O
NaOH + H
22. Consider the description: copper(II) oxide reacts with sulfuric acid to produce copper(II) sulfate and water.
List the steps required to write its balanced chemical equation. State how to determine which of the five
general types of reaction this represents.
23. Sulfur in gasoline can produce sulfuric acid, H2SO4, according to the two-step process shown below. For each
125 g of sulfur in gasoline, how many moles of H2SO4 will be produced?
24. Given the reaction represented by the equation Mg + 2HCl
H2 + MgCl2, determine to two decimal places
the molar masses of all substances involved. Then write the molar masses as conversion factors.
25. What mass is grams of potassium chloride is produced if 100. g of potassium chlorate decompose according
to the following equation?
26. What mass in grams of sodium hydroxide is produced if 20.0 g of sodium metal react with excess water
according to the chemical equation Na(s) + H2O(l)  NaOH(aq) + H2(g)?
27. The reaction of 100. g of salicylic acid, C7H6O3, with excess acetic anhydride produces 50.0 g of aspirin,
C9H8O4, according to the equation below. What is the percentage yield for this reaction?
28. In the decomposition of hydrogen peroxide, the percentage yield of oxygen is 93.0%. What is the actual yield
in grams of oxygen if you start with 100. g of H2O2? The reaction proceeds according to the equation
.
29. Find the number of each kind of atom in each of the following: (a) 3 molecules of carbon dioxide
(CO2); (b) 2 molecules of silicon tetrafluoride (SiF4);(c) 5 molecules of nitric acid (HNO3).
30. (a) A sample of ammonia (NH3) contains 7.22 moles of ammonia. How many molecules of ammonia
are in the sample? (b) A second sample of ammonia contains 3.87  1021 molecules of ammonia.
How many moles of ammonia are in the sample?
31. Find the molar masses of the following substances: (a) sodium sulfate (Na2SO4); (b) dinitrogen
tetroxide (N2O4).
32. Calculate the number of moles of sulfur dioxide (SO2) in 76.1 g SO2.
33. Suppose that a sample of the molecular substance carbon tetrabromide (CBr4) has a mass of 7.57
grams. Calculate (a) the number of moles and (b) the number of molecules.
34. A student is given 9.15  1021 formula units of ammonium sulfate, (NH4)2SO4, and is asked to
determine its mass. What should the student find the mass of the sample to be?
35. Determine the percentage composition of magnesium carbonate (MgCO3).
36. A sample of a molecular compound was analyzed and found to contain 9.09 grams carbon (C), 1.52
grams of hydrogen (H), and 14.40 grams of fluorine (F). Determine the empirical formula of the
compound. Given the added information that the molar mass of the compound is 66.0 g/mol,
determine the molecular formula of the compound.
37. When potassium chlorate, KClO3, is heated, it decomposes to produce potassium chloride and
oxygen gas. How many grams of oxygen gas will be produced when 2.50 moles of potassium
chlorate is decomposed? (atomic masses: O = 16.0; Cl = 35.5; K = 39.1)
38. Iodine reacts with concentrated nitric acid according to the following equation.
10 HNO3 + I2  2 HIO3 + 10 NO2 + 4 H2O
What mass of HIO3 is produced when 15.0 grams of iodine reacts with nitric acid? (atomic masses:
H = 1.0; N = 14.0; O = 16.0; I = 126.9)
39. When propane, C3H8, reacts completely with oxygen, carbon dioxide and water are produced. How
many milliliters of carbon dioxide will be produced if 200mL of oxygen reacts with propane? The
volumes of both gases are at STP.
40. When Pb(NO3)2 (aq) is mixed with NaCl (aq), a precipitate of PbCl2 (s) is formed. A solution
containing 8.00 grams of Pb(NO3)2 is mixed with a solution containing 2.25 grams of NaCl. What is
the maximum amount of PbCl2 (s) that will form from this reaction?
41. At STP, a sample of 35 mL of oxygen is mixed with 20 mL of hydrogen and the mixture ignited.
What is the volume, at STP, of any unreacted gas that remains?
42. Methane burns in oxygen according to the following equation.
CH4 (g) + 2 O2 (g)  CO2 (g)
+ 2 H2O (g)
A mixture containing 24.0 g CH4 and 128 g O2 is ignited. How much CO2 is produced?