Chemistry
CA#3 Study Guide
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14.
What is the mass in grams of 6.52 moles of C8H16?
20
How many moles of copper are in 6.25 x 10 atoms of copper?
How many moles are in 625 g of magnesium hydroxide?
24
3.25 x 10 atoms of carbon would be how many moles of carbon?
How many molecules are in 12.0 grams of ethane?
Calculate the number of atoms in 28.0 grams of silver.
What is the molar mass of barium nitrate?
A molecule has an empirical formula of PH3. Which of the following would be a possible molecular
formula? A) PH4 B) P2H3
C) P2H5 D) P2H6
What is the percent chromium in magnesium chromate?
A compound’s empirical formula is C2H5 and the molar mass of the compound is 87.21 g/mole. Determine
the molecular formula of the compound.
A compound contains 18.11 g carbon and 481.9 g bromine. What is the empirical formula of the
compound?
Calculate the percent composition of copper (II) sulfate.
A compound contains 54.5 % carbon, 13.6 % hydrogen, and 31.8 % nitrogen. Calculate the empirical
formula.
Which of the following compounds have the same empirical formula?
A) CO2 and SO2
C) C8H20 and C30H12
B) N2O5 and N3O7
D) C7H14 and C12H24
15. Using the reaction below, calculate the grams of PH3 are produced when 4.6 g of hydrogen reacts?
1 P4 + 6 H2  4 PH3
16. Using the reaction below, calculate the number of moles of iron that would be produced when 0.50
moles of aluminum react.
2 Al + 3 FeO  3 Fe + 1 Al2O3
17. Using the reaction in #16, calculate the number of moles of aluminum oxide produced when 52.0 g of
FeO react.
18. Using the reaction below, calculate the grams of phosphoric acid produced when 12.0 moles of water
react.
1 P4O10 + 6 H2O  4 H3PO4
19. Using the reaction below, calculate the grams of water needed to produce 15.5 moles of hydrogen.
1 Be + 2 H2O  1 Be(OH)2 + 1 H2
20. What solid forms, if any, when KNO3 (aq) is added to Mg(NO3)2 (aq) ?
KNO3 (aq) + MgCl2 (aq)  KCl + Mg(NO3)2
A) KNO3
C) KCl
B) Mg(NO3)2
D) No solid forms
21. What solid forms, if any, when K2CO3 (aq) is added to MgBr2 (aq) ?
K2CO3 (aq) + MgBr2 (aq)  ??
22. An example of dissociation is when an ______________ compound is added to water and breaks apart
into __________.
23. The limiting reactant determines when a reaction will ______________ and how much
____________________ can theoretically be produced.
24. An example of dispersion is when a __________________ compound is added to water and separates into
individual _____________________, but the chemical formula does not change.
25. A solute is _________________________________.
26. A solvent is ________________________________.
27. Dilution occurs when water is added to a ___________________ solution. The volume
_________________ and the __________________ of solute stay the same.
28. What is the molarity of a solution that contains 175 g of NaCl in 4.00 L of solution?
29. A student takes 275 mL of a 0.75 M solution of KI and increases the volume to 1000.0 mL (by adding
water) to make a more dilute solution. What is the molarity of the new solution?
30. A 2.55 L solution of NaOH has a concentration of 0.575 M. How many moles of NaOH are in the solution?
31. If 32 grams of NaOH are dissolved into 125 g of water, what is the percent by mass of the sodium
hydroxide solution?
Use the graph to the left to answer the following
questions:
32. Identify the following solutions as
saturated, unsaturated, or supersaturated:
A) 80 grams of potassium nitrate in 100 mL
of water at 50 °C.
B) 130 grams of sodium nitrate in 100 mL of
water at 40 °C.
C) 10 grams of potassium chlorate in 100 g
water at 30 °C.
D) 50 grams of ammonium chloride in 100 g
water at 80 °C.
Use the graph above to answer the following questions:
33. What mass of ammonium chloride is needed to make a saturated solution at 70 °C in 100 mL of water?
34. What temperature is required to completely dissolve 80 grams of potassium nitrate in 100 g of water?
Honors Only (#35 -#47)
35. Write the net ionic reaction for aqueous potassium phosphate added to aqueous zinc nitrate. Include
phase notations.
36. Write the dissociation reaction when solid potassium chloride is added to water. Include phase
notations.
37.
Write the dissociation reaction when solid magnesium chloride is added to water. Include phase
notations.
38. For a reaction, the theoretical yield is calculated to be 65.0 g N 2. When a student carries out the
experiment, they collect 52.5 g N2. Determine the percent yield collected by the student.
39. How many mL of a 2.00 M KBr solution are needed to make 500.0 mL of 0.650 M KBr?
40. Use the solubility graph to determine if the following statements are true or false concerning a solution
that contains 5 grams of potassium chlorate in 100 mL of water at 40 °C.
A) The solution is saturated.
B) Some solid would be present at the bottom of the container.
C) You could dissolve 10 more grams in the solution.
41. Use the solubility graph to answer the following:
A) For sodium nitrate, as the temperature increases, _________ (more or less) solid is able to dissolve.
B) For sodium nitrate, as the temperature decreases, what would eventually happen to the solid
dissolved in the solution?
42. Ionization occurs when an ______________ is added to water and forms____________.
43. The solubility of NaCl at 20 °C is 36.0 g in 100 g of water. Identify the following solutions as saturated,
unsaturated, or supersaturated:
A) 25.0 g NaCl in 75 g of water at 20 °C.
B) 80.0 g NaCl in 200 g of water at 20 °C.
C) 18.0 g NaCl in 50 g of water at 20 °C.
44. When 10.5 grams of Pb(NO3)2 is heated in a decomposition reaction, the actual yield of PbO collected is
5.9 grams. What is the percent yield?
2 Pb(NO3)2  2 PbO + 4 NO2 + 1 O2
45. A) How many grams of copper can be obtained when 81 g of Al reacts with 479 g of CuSO 4?
B) What is the limiting reactant?
C) What is the excess reactant?
2 Al + 3 CuSO4  1 Al2(SO4)3 + 3 Cu
Do the following problems in class:
46. 2 Na + 1 FeSO4  1 Fe + 1 Na2SO4
If 25 mL of a 0.60 M FeSO4 solution is used, how many grams of iron can form?
47. 3 Ca + 2 Cu3PO4  6 Cu + 1 Ca3(PO4)2
What is the molarity of calcium phosphate solution that is produced when 35 grams of calcium reacts.
The total volume of the solution is 750.0 mL.
Answers
1. 732 g
2. 0.00104 moles
3. 10.7 moles
4. 5.40 moles
23
5. 2.40 x 10 molecules
23
6. 1.56 x 10 atoms
7. 261.36 g/mole
8. D
9. 37.06 %
10. C6H15
11. CBr4
12. 39.81 % Cu, 20.09 % S, 40.10 % O
13. C2H6N
14. D
15. 52 g
16. 0.75 moles
17. 24.6 g
18. 784 g
19. 559 g
20. D, No solid forms.
21. MgCO3 is the solid.
22. ionic, ions
23. stop, product
24. covalent, molecules
25. The substance(s) present in the smaller amount (usually what is dissolved)
26. The substance present in the greater amount (for aqueous solutions, the solvent is water)
27. concentrated, increase, moles
28. 0.749 M
29. 0.21 M
30. 1.47 moles
31. 20. %
32. A) saturated B) supersaturated C) saturated D) unsaturated
33. 60 g
34. 50 °C
Honors Only
35. 2 PO4 -3 (aq) + 3 Zn +2 (aq)  1 Zn3(PO4)2 (s)
H2O
36.
1 K +1 (aq) + 1 Cl -1 (aq)
1 KCl (s)
H2O
37. 1 MgCl2 (s)
1 Mg +2 (aq) + 2 Cl -1 (aq)
38. 80.8 %
39. 163 mL
40. A) false B) false C) true
41. A) more B) some solid would precipitate (form) out of solution and settle to the bottle of the
container.
42. acid, ions
43. A) unsaturated B) supersaturated C) saturated
44. 83 %
45. 191 g Cu, LR = CuSO4, XS reactant = Al
46. 0.84 g
47. 0.39 M