Download Chemistry Workbook 4

Chem 1A
Dr. White
Updated 10/23/13
Chemistry Workbook 4: Problems For Exam 4
4-1 Reactions
1. Calculate the oxidation number of sulfur in sodium metabisulfite, Na2S2O5.
2. Sodium tripolyphosphate is used in detergents to make them effective in hard water. Calculate the
oxidation number of phosphorus in Na5P3O10.
3. Identify the oxidizing agent in the following redox reaction.
2+
2+
Hg (aq) + Cu(s) → Cu (aq) + Hg(l)
4. For each of the following reactions, determine what the products of each reaction will be. When you
have predicted the products, balance the equation and write the net ionic equation.
____ Ca(OH)2 (s) + ____ HCl (aq) 
____ Pb(NO3)2 (aq) + ____ K2CrO4 (aq) 
____ AgNO3 (aq) + ____ Na2CO3 (aq) 
____ Zn (s) + ____ HCl (aq) 
_____HF (aq) + KOH (aq) 
5. Predict the products of the following reactions and list the type of reaction (single displacement,
precipitate, acid-base, combustion, combination, or decomposition). If no reaction occurs, write “NR”.
__ Ag (s) + __CuSO4 (aq) 
__ HI (aq) + __ Na2CO3 (aq)
__ O2 (g) + __ H2 (g) 
__ H2O (l) + __ Ag (s) 
__ LiNO3 (aq) + __Ag (s) 
__ N2 (g) + __ O2 (g) 
(Nitrogen has a +4 oxidation state in the product)
__ H2SO4 (aq) + __ NaOH (aq) 
__ C4H8 (g) + __ O2 (g) 
__ Zn (s) + __ AgNO3 (aq)
__ KOH (aq) + __ H2SO4 (aq) 
__ Na2O (s) + heat 
___ NaCl (aq) + KOH (aq) →
___ Sr (s) + H2O (l) →
___ Mg(ClO4)2 (s) + heat →
potassium metal + oxygen →
aqueous potassium iodide +aqueous bromine →
calcium metal+ hydrochloric acid →
aqueous iron(II) sulfate + aqueous ammonium sulfide →
sodium bromide (aq) + chlorine (aq) →
6. Balance the following redox reactions.
4+
3+
2+
Cr (s) + Sn (aq) → Cr (aq) + Sn (aq)
(neutral)
22Br2 (l) + SO3 (aq) → Br (aq) + SO4 (aq)
(acidic)
2+
CuS (s) + NO3 (aq) → Cu (aq) + NO2 (g) + S (s) (acidic)
-
-
-
Cl2 (aq) + I (aq) → Cl (aq) + IO3 (aq)
(basic)
7. Return to the previous problem and for each reaction, label the oxidizing agent (OA) and the reducing agent
(RA)
1 Chem 1A
Dr. White
Updated 10/23/13
2 8. In each case below use solubility rules or the activity series to predict if a reaction will occur or not. (see notes
for activity series; activity series will be given on quiz and exam)
a. NaCl (aq) +AgNO3 (aq) →?
b. K2SO4 (aq) +NH4Cl (aq)→?
c. Cu (s) +AgNO3 (aq) →?
d. Zn (s) +MgSO4 (aq) →?
e. Ag (s) +SnCl2 (aq)→?
9. Predict the products of the following reactions. Then, balance each chemical equation. If it is a redox
reaction, indicate what has been oxidized and reduced.
a.
b.
c.
d.
e.
f.
g.
Ni (s) + AgNO3 (aq)  (nickel becomes Ni
Al (s) + CuSO4 (aq) 
K (s) + H2O (l) 
Zn (s) + HCl (aq) 
NaOH (aq) + Fe2(SO4)3 (aq) 
Na2SO4 (aq) + Ba(NO3)2 (aq) 
MgCO3 (aq) + HCl (aq) 
2+
- it’s most common ox. State)
10. Translate the following sentences into balanced, chemical equations. Please include states and classify
each type of reaction (as redox, acid-base, or ppt). Also, write the net ionic equation.
a. Solutions of sodium chloride and silver (I) nitrate react to form silver chloride and sodium nitrate.
b. solutions of sulfuric acid (H2SO4) and barium hydroxide react to form barium sulfate and one other
product.
c. sodium metal reacts violently with water to form sodium hydroxide and one other product (a gas).
d. Liquid acetaldehyde (CH3CHO) is combusted.
e. when sulfuric acid (H2SO4) reacts with sodium hydrogen carbonate, three products form.
h. Potassium hydroxide reacts with nitrous acid
i. Acetic acid reacts with sodium hydroxide.
3+
2-
11. Balance the following redox reaction: Cr (aq) + H2O2(aq) → CrO4 (aq) (basic) [Hint: For step 1: one of
+
your half reactions will just be H2O2 → nothing; you will balance the H’s and O’s with water and H ]
4-2 Stoichiometry
1. Nitroglycerin (C3H5N3O9) is a powerful explosive. How many grams of CO2 are produced from 10.0 g of
nitroglycerin?
C3H5N3O9 (g)→ N2 (g) + CO2 (g) + H2O (g) + O2 (g) (unbalanced!)
2. When chlorine and fluorine gas are mixed and chlorine trifluoride gas is produced. If 0.750 moles of
chlorine gas and 3.00 moles of fluorine gas are mixed, how many moles of each substance is present at
the end of the reaction?
3. How many grams of solid aluminum sulfide can be prepared by the reaction of 10.0 g aluminum with
15.0 g sulfur. What mass of the excess reactant is present at the end of the reaction?
4. Hydrofluoric acid is produced by reacting aqueous calcium fluoride with sulfuric acid. How many grams
of HF can be made by the reaction of 12.8 g of CaF2 and 13.2 g of H2SO4? What mass of excess
reactant is left at the end of the reaction? The other product for the reaction is a precipitate.
5. When 18.5 g of methane (CH4) and 43.0 g of chlorine gas undergo a reaction that has an 80.0% yield,
what is the actual (experimental) mass of chloromethane (CH3Cl) that forms? Hydrogen chloride gas is
the other product.
Chem 1A
Dr. White
Updated 10/23/13
3 6. 10.0mL of 0.500M silver nitrate and 25.0 mL of 0.725M aluminum chloride are mixed together. How
many grams of precipitate are produced? Also, what are the concentrations of all the ions after the
reaction is complete (assume the volumes are additive)?
7. 1.00 L of 0.500 M magnesium nitrate is added to 1.00 L of 0.500 M potassium hydroxide. What mass of
precipitate is formed and what are the concentrations of all the ions is solution after the reaction is
complete? The volumes are additive.
8. A person’s blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with a
3+
potassium dichromate solution. The redox reaction takes placed in acid and the products are Cr and a
gas that turns limewater cloudy. If 35.46 mL of 0.05961 M potassium dichromate is required to titrate
28.00 g of plasma, what is the mass percent of alcohol in the blood? (HINT: start with a net ionic redox
reaction and then balance it).
9. In mammals, lactose is broken down to glucose (C6H12O6), the key nutrient for generating chemical
potential energy.
a. What is the mass percent of each element in glucose?
b. How many grams of Carbon are in 16.55 g glucose?
10. A dry cleaning solvent (molar mass = 146.99 g/mol) that contains C, H, and Cl is suspected to be a
cancer causing agent. When a 0.250-g sample was studied by combustion analysis, 0.451 g of CO2
and 0.0617 g of H2O formed. Find the molecular formula.
11. Calculate the volume of 0.100 M sulfuric acid required to reach the endpoint in a titration with 25.0 mL of
0.0821 M KOH.
12. A 0.1873 g sample of pure solid acid, H2X was dissolved in water and titrated with 0.1052 M NaOH
solution. If 41.89 mL of the NaOH solution is needed to reach the equivalence point, calculate the molar
mass of the acid.
4-3 Gas Laws and Gas Stoichiometry
1. "The volume of an ideal gas is directly proportional to the number of moles of the gas at constant
temperature and pressure" is a statement of _____________ Law.
2. Which of the lines on the figure below is the best representation of the relationship between the volume
of a gas and its pressure, other factors remaining constant?
3. A sample of an ideal gas has its volume doubled while its temperature remains constant. If the original
pressure was 100 torr, what is the new pressure?
4. A sample of nitrogen gas at 298 K and 745 torr has a volume of 37.42 L. What volume will it occupy if
the pressure is increased to 894 torr at constant temperature?
5. State Charles's Law and illustrate it with a graph, using standard x-y coordinate axes. Be sure to label
the axes unambiguously with the correct gas variables.
6. Briefly state the conditions corresponding to STP (standard temperature and pressure).
Chem 1A
Dr. White
Updated 10/23/13
4 7. A 255-mL gas sample weighing 0.292 g is at 52810 Pa and 127°C.
a. How many moles of gas are present?
b. What is the molar mass of the gas?
8. On a cold day an individual takes in a breath of 375 mL at 745 mm Hg and -10°C. What is the volume
(mL) of air in the lungs at 749 mm Hg and 37°C?
9. A 162 L drum used for crude oil is steam cleaned. Assuming ideal gas behavior, calculate the mass, g,
of water required to fill the barrel at 1.00 atm if the steam is at 110.°C.
o
10. What is the density in g/L of BrF3 at 425 torr and 77 C?
-3
11. At 1000°C and 10. torr, the density of a certain element in the gaseous state is 2.9 x 10 g/L. Determine
the identity of the element.
12. Aluminum metal shavings (10.0 g) are placed in 100. mL of 6.00 M hydrochloric acid. What is the
maximum volume of hydrogen, measured at STP, which can be produced?
13. Copper reacts with dilute nitric acid according to the equation:
3Cu(s) + 8HNO3(aq) → 3Cu(NO3)2(aq) + 2NO(g) + 4H2O(l)
A 200.0 mL sample of 2.00 mol/L nitric acid is added to 30.48 g of copper. Determine which reactant is
the limiting reagent. What volume of nitrogen monoxide, measured at 99.5 kPa and 20°C, would be
produced?
1.
2.
3.
4.
4-1: Reactions
+4
+5
2+
Hg
1 Ca(OH)2 (s) + 2 HCl (aq)  2 H2O (l) + CaCl2 (aq)
+
2+
Ca(OH)2 (s) + 2H (aq) → 2 H2O (l) + Ca (aq)
1 Pb(NO3)2 (aq) + 1 K2CrO4 (aq)  2 KNO3 (aq) + PbCrO4 (s)
2+
2Pb (aq) + CrO4 (aq) → PbCrO4 (s)
2 AgNO3 (aq) + 1 Na2CO3 (aq)  Ag2CO3 (s) + 2 NaNO3 (aq)
+
22Ag (aq) + CO3 (aq) → Ag2CO3 (s)
1 Zn (s) + 2 HCl (aq)  ZnCl2 (aq) + H2 (g)
+
2+
1 Zn (s) + 2H (aq) → Zn (aq) + H2 (g)
1HF (aq) + 1KOH (aq)  KF (aq) + H2O (l)
HF (aq) + OH (aq) → F (aq) + H2O (l)
5. 2 Ag (s) + 1 CuSO4 (aq)  NR
2 HI (aq) + 1 Na2CO3 (aq)  2 NaI (aq) + H2O (l) + CO2 (g)
1 O2 (g) + 2 H2 (g)  2 H2O (l)
1 H2O (l) + 1 Ag  NO RXN
1 LiNO3 (aq) + 1 Ag (s)  NR
1 N2 (g) + 2 O2 (g)  2 NO2 (g)
1 H2SO4 (aq) + 2 NaOH (aq)  2 H2O (l) + 1 Na2SO4(aq)
1 C4H8 (g)+ 6 O2 (g)  4 CO2 (g) + 4 H2O (l or g)
Zn + 2 AgNO3  1 Zn(NO3)2 (aq) + 2 Ag (s)
2 KOH (aq) + 1 H2SO4 (aq)  1 K2SO4 (aq) + 2 H2O (l)
2 Na2O (s)  4 Na (s) + 1 O2 (g)
NaCl (aq) + KOH (aq) → NO RXN
Sr (s) + 2H2O (l) → Sr(OH)2 (aq) + H2 (g)
Mg(ClO4)2 (s) → MgCl2 (s) + 4 O2 (g)
4K (s) +O2 (g) →2K2O (s)
2KI(aq)+Br2 (aq)→I2 (aq) +2KBr (aq)
Type: Acid-Base
Type: Combination
Type:
Type:
Type:
Type:
Type:
Type:
Combination
Acid-Base
Combustion
Single Displacement
Acid-Base
Decomposition
Type:
Type:
Type:
Type:
Single Displacement
Decomposition
Combination
Single Displacement
Chem 1A
Dr. White
Updated 10/23/13
Ca (s) +2HCl (aq)→CaCl2 (aq) +H2 (g)
FeSO4 (aq)+ (NH4)2S (aq)→ FeS (s)+ (NH4)2SO4 (aq)
2NaBr (aq) +Cl2 (aq) →2NaCl (aq) +Br2 (aq)
4+
3+
2+
6. 2Cr (s) +3Sn (aq) →2Cr (aq) +3Sn (aq)
2-
2-
-
Type: Single Displacement
Type: Precipitation
Type: Single Displacement
+
H2O (l)+Br2 (l) +SO3 (aq)→ SO4 (aq) +2Br (aq) +2H (aq)
+
2+
4H (aq) +CuS (s) +2NO3 (aq)→Cu (aq) +S (s) +2NO2 (g) +2H2O (l)
-
-
-
-
3Cl2 (g) +6OH (aq) +I (aq) →6Cl (aq) +IO3 (aq) +3H2O (l)
4+
7. 2Cr (s) +3Sn (aq) →2Cr
RA
3+
(aq) +3Sn
2+
(aq)
OA
2-
H2O (l)+Br2 (l) +SO3 (aq)→ SO4
2-
-
+
(aq) +2Br (aq) +2H (aq)
OA
RA
+
2+
4H (aq) +CuS (s) +2NO3 (aq)→Cu (aq) +S (s) +2NO2 (g) +2H2O (l)
RA
OA
-
-
-
-
3Cl2 (g) +6OH (aq) +I (aq) →6Cl (aq) +IO3 (aq) +3H2O (l)
OA
8.
RA
a. yes, a ppt forms
b. no (no ppt forms)
c. yes (Cu is more active than Ag – it’s higher up on the activity series)
d. no (Zn is less active than Mg - it’s lower on the activity series)
e. no (Ag is less active than Sn)
+
9.
a. Ni (s) + 2 AgNO3 (aq) Ni(NO3)2 (aq)+ 2Ag (s); Ni is oxidized; Ag in AgNO3 is reduced
2+
b. 2Al (s) + 3CuSO4 (aq) Al2(SO4)3 (aq) + 3Cu (s); Al is oxidized; Cu in CuSO4 is reduced
c. 2K (s) + 2H2O (l) 2KOH (aq) + H2 (g) ; K is oxidized; H in H2O is reduced
d. Zn (s) + 2 HCl (aq) 
ZnCl2 (aq) + H2 (g); Zn is oxidized; H in HCl is reduced
e. 6 NaOH (aq) + Fe2(SO4)3 (aq) 3Na2SO4 (aq) + 2Fe(OH)3 (s)
f. Na2SO4 (aq) + Ba(NO3)2 (aq) BaSO4 (s) + 2NaNO3 (aq)
g. MgCO3 (aq) + 2 HCl (aq)  MgCl2 (aq) + H2O (l) + CO2 (g)
10.
a. NaCl (aq) + AgNO3 (aq) → AgCl (s) + NaNO3 (aq)
precipitate
+
–
Ag (aq) + Cl (aq) → AgCl (s)
b. H2SO4 (aq) + Ba(OH)2 (aq) → BaSO4 (s) + 2H2O (l) acid base and ppt!
+
22+
2H (aq) + SO4 (aq) + Ba (aq) + 2OH (aq) →BaSO4(s) + 2H2O (l)
c. 2Na (s) + 2H2O (l) → 2NaOH (aq) + H2 (g)
redox
+
2Na (s) + 2H2O (l) → 2Na (aq) + 2OH (aq) + H2 (g)
d. 2CH3CHO (l) + 5O2 (g) → 4CO2 (g) + 4H2O (l or g)
redox
net ionic the same as above
e. H2SO4 (aq) + 2NaHCO3 (aq) → 2CO2 (g) + 2H2O (l) + Na2SO4 (aq) acid-base
+
2H (aq) + 2 HCO3 (aq) → 2CO2 (g) + 2H2O (l)
f. KOH (aq) + HNO2 (aq) → H2O (l) + KNO2 (aq) acid-base
5 Chem 1A
Dr. White
-
Updated 10/23/13
-
OH (aq) + HNO2 (aq) → H2O (l) + NO2 (aq)
g. HC2H3O2 (aq) + NaOH (aq) → H2O (l) + NaC2H3O2 (aq)
HC2H3O2 (aq) + OH (aq) → H2O (l) + C2H3O2 (aq)
3+
-
acid-base
2-
11. 2Cr (aq) + 3H2O2 (aq) + 10OH (aq) → 2CrO4 (aq) + 8H2O (l)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
4-2: Stoichiometry
5.81 g
0 mol Cl2, 0.75 mol F2, and 1.50 mol ClF3
23.4 g product; 1.6 g excess reactant
5.39 g HF; 2.3 g excess reactant
24.5 g
3+
0.717 g ppt 1.41 M Cl ; 0.143 M NO3 0.518 M Al
2+
+
0M OH-, 0.125 M Mg , 0.250 M K , 0.500 M NO3 , 14.6 g ppt
0.1739%
.
a. 40.00% C; 6.714% H; 53.29% O
b. ans: 6.620 g
C6H4Cl2
10.3 mL
85.00 g/mol
13. 4-3 Gas Laws and Gas Stoichiometry
Avagadro’s Law
E
50 torr
289 torr
At constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute
temperature. The plot should be V vs. T, showing a straight line of positive slope, passing through the
origin
At STP, the pressure is one atmosphere and the temperature is 0°C (273.15K)
-3
a. 4.05 × 10 mol
b. 72.1 g/mol
440. mL
92.9 g
2.67 g/L
Na
6.72 L
HNO3 is limiting, 2.45 L NO
6