Chemistry X Lab Review Problems
Candle Lab
1) For each of the following, identify if the statement is an observation or an interpretation and whether it is qualitative or
quantitative.
a. The candle is 5.51 ± 0.05 cm tall.
b. The candle is cylindrical in shape.
c. The candle burns by reacting with oxygen.
d. The wax melts and drips down the side of the candle.
e. The flame produces light and heat.
Accuracy/Precision Lab
2) Read the following measurements and record the proper uncertainty.
Expt. #7 - Mass Relations
2) Given the following experimental data,
Mass of Pb(NO3)2 used
3.31 ± 0.01 g
Mass of K2CrO4 used
1.94 ± 0.01 g
Mass of 50 mL beaker
65.34 ± 0.01 g
Mass of 125 mL erlenmeyer flask
81.59 ± 0.01 g
Mass of filter paper
1.08 ± 0.01 g
Mass of erlenmeyer and solid
83.58 ± 0.01 g
Mass of beaker, filter paper, and precipitate
69.65 ± 0.01 g
a. Does this reaction support the law of conservation of mass (show a calculation to support your answer).
b. Use experimental data to balance this equation:
___ Pb(NO3) 2 + ___ K2CrO4  ____ KNO3 + ____ PbCrO4
c. What is the percent yield for the production of KNO3?
d. How would each of the following errors affect your yield of PbCrO 4 and KNO3?
i.
The beaker, filter paper and precipitate were not dried long enough.
ii.
The erlenmeyer was not heated long enough.
iii.
There was a small tear in the filter paper.
iv.
You used more Pb(NO3)2 than you were supposed to.
v.
Some of the filtrate was spilled.
vi.
Some of the original Pb(NO3)2 solution was spilled prior to mixing it with the K2CrO4 solution.
Expt. S-3 Silver Tree Lab
3) Given the following experimental data,
Initial mass of vial and solid AgNO3
4.39 ± 0.01 g
Final mass of vial and solid AgNO3
1.31 ± 0.01 g
Initial mass of copper wire
9.67 ± 0.01 g
Final mass of copper wire
9.09 ± 0.01 g
Mass of 50 mL beaker
62.89 ± 0.01 g
Mass of filter paper
1.17 ± 0.01 g
Mass of beaker, filter paper, and silver
66.08 ± 0.01 g
a. Use experimental data to balance this equation: (Assume a 1:1 ratio between Cu and Cu(NO 3)2)
___ AgNO3+ ___ Cu  ____ Cu(NO3)2 + ____ Ag
b. How would each of the following errors affect your yield of silver?
i. Some copper was mixed in with the silver.
ii.
Some silver was not scraped off the copper wire.
iii.
The copper wire was not dry when the final mass was measured.
iv.
The beaker, filter paper and silver were not dried long enough.
v.
The filter paper caught on fire while being dried.
Expt. #4 - "Behavior of Gases"
4) Use the following data/graphs to answer the questions below.
Volume (mL)
Pressure (Books)
35.0
1
25.1
2
19.5
3
16.0
4
13.5
5
a.
b.
How are pressure and volume of a gas related? (directly or inversely)
What is the value of atmospheric pressure in the unit "books?
Expt. #5 - "Equal Volumes of Gases"
5) Given the following experimental data,
Mass of an empty 0.902 L bag
3.17 ± 0.01 g
Mass of a 0.902 L bag filled with oxygen gas
3.29 ± 0.01 g
Mass of a 0.902 L bag filled with carbon dioxide gas
3.71 ± 0.01 g
Density of air at lab conditions
1.12 ± 0.01 g/L
Molar Mass of oxygen
32.00 ± 0.01 g
a. Using experimental data, determine the molar mass of carbon dioxide.
b. What is your percent error?
c. Why is Avogadro's Hypothesis important for this lab?
d. If the bag wasn't as full when the carbon dioxide was added, how would that affect its molar mass?
Expt. #3 - "Warming and Cooling Behavior"
6) Analyze the graph to answer the questions below.
45°C
T
e
m 35°C
p
D
C
B
20°C
15°C
A
Time (min)
E
a.
b.
c.
d.
At what temperature does the unknown melt?
Which lines represent potential energy changes?
Which lines represent kinetic energy changes?
If more of the unknown were used how would that affect
i.
The lines that represent kinetic energy changes?
ii.
The lines that represent potential energy changes?
Expt. #12 - "Heat of Solidification of para-dichlorobenzene"
7) Given the following experimental data,
Mass of an empty test tube
30.56 ± 0.01 g
Mass of test tube filled with C6H4Cl2
59.29 ± 0.01 g
Volume of water in styrofoam cup
150 ± 1 mL
Initial Temperature
21.5 ± 0.2 °C
Final Temperature
27.2 ± 0.2 °C
a. What is the molar heat of solidification of para-dichlorobenzene?
b. Write the thermochemical equation that represents the solidification of para-dichlorobenzene.
Expt. #9 - "Heat of Combustion of a Candle"
8) Given the following experimental data,
Mass of a candle
23.26 ± 0.01 g
Mass of candle after burned
20.78 ± 0.01 g
Volume of water heated
100 ± 1 mL
Initial Temperature
15.3 ± 0.2 °C
Final Temperature
37.2 ± 0.2 °C
a. What is the heat of combustion per gram of candle burned?
b. If some heat were lost to the surroundings, how would this affect your answer to "a"?
Heat of Fusion of Ice
10) In one experiment you calculated the molar heat of fusion of ice, which the amount of energy needed to melt one mole of
ice in kJ/mol. Using the experimental data listed below, calculate the molar heat of fusion of ice.
Data
Mass of empty, dry Styrofoam cup
4.25 ± 0.01g.
Mass of cup plus warm water
100.40 ± 0.01g.
Initial water temperature
25.0 ± 0.2 oC
Mass of cup after ice melted
112.40 ± 0.01g.
Temp of water after ice melted
0.0 ± 0.2 oC
i. Calculate the mass of the warm water in the Styrofoam cup.
ii. Calculate the temperature change that the warm water underwent as it melted the ice.
iii. Calculate the amount of heat lost, in Joules, by the warm water as it melted the ice.
iv. Calculate the mass of the ice that melted.
v. What amount of heat, in Joules, melted the ice.
vi. Calculate the heat of fusion for water in Joules per gram.
vii. Calculate the molar heat of fusion for water in kilojoules per mole.
viii. Calculate the percent error for the value in 7, just above. The true value is 6.02 kJ/mol.
Expt. #19 – Heat of Reaction –
11.) When solid sodium hydroxide is added to a solution of hydrochloric acid, heat is given off. From the following lab
data, determine the experimental molar heat of reaction, in kJ/mol.
mass solid NaOH plus weighing paper:
6.37 ± 0.01 g
mass of weighing paper:
1.00 ± 0.01 g
volume of 0.50 M HCl solution used:
200 ± 1 mL
initial temperature of HCl solution:
22.2 ± 0.2 oC
final temperature reached:
29.4 ± 0.2 oC
i. Calculate the number of moles of solid NaOH used:
ii. Calculate the amount of heat absorbed by the water:
iii. Calculate the molar heat of reaction in kJ/mol:
iv. Write the thermochemical equation for this reaction.
Expt. #21 – “LeChatelier’s Principle”
12) Predict what effect, if any, the following changes would have on the color of the equilibrium mixture.
a.
b.
c.
d.
e.
Heat + Fe3+ (aq) + SCN- (aq) <==> FeSCN2+ (aq)
(dk. Red/brown)
Increasing the temperature of the surroundings.
Increasing the pressure of the surroundings.
Adding drops of 0.10 M Fe(NO3)3 to the mixture.
Adding drops of 0.10 M Na2HPO4 to the mixture. (HPO4- ions react with Fe3+ ions to form a white precipitate.)
Adding drops of 0.10 M KNO3 to the mixture.
Expt. #13 - "Formula of a Precipitate"
13) Aqueous solutions of calcium chloride and sodium oleate react in a double replacement
reaction to form a
precipitate, solid calcium oleate and aqueous sodium chloride. Eight test
tubes were set up with different
combinations of the two reactants. Each test tube was
filled with a total volume of nine milliliters of solution. For
example, in test tube one, one milliliter of 0.1 M calcium chloride solution is added to nine milliliters of 0.1 M sodium
oleate
solution.
It is the amount of precipitate formed in each test tube that is of interest in this experiment.
each of the eight precipitate samples were filtered, dried and massed.
Test tube #
mL 0.1M Ca+2 ion soln
mL 0.1 M oleate ion soln
mole ratio(mol Ca+2: mol oleate ion)
mass of precipitate (g)
1
1
8
1:8
0.63
2
2
7
2:7
0.80
3
3
6
1:2
1.00
4
4
5
4:5
0.84
5
5
4
5:4
0.67
6
6
3
2:1
0.50
7
7
2
7:2
0.33
Once formed,
8
8
1
8:1
0.18
a) From the lab data shown above, determine the correct experimental chemical formula of the precipitate. C18H33O2 is the
chemical formula for the oleate ion. Please note - the charge of the oleate ion has been left off on purpose.
i.
Ca2(C18H33O2)7
ii.
Ca(C18H33O2)2
iii.
Ca4(C18H33O2)5
iv.
Ca5(C18H33O2)4
v.
Ca2 C18H33O2
b. Briefly explain how you could you have determined the correct chemical formula of the precipitate had it not been one of
the above options?
c. What mass of solid calcium chloride would be needed to make 250.0mL of a 0.100 M CaCl2 solution?
Expt. #14 – “Precipiate Reactions”
14) a. Given the following data, what is the formula for the precipitate formed?
Solutions
Ba(NO3)2
NaCl
AgNO3
NR
PPT
(box A)
(box B)
NaCl
NR
X
(box C)
b. Using experimental data why did you identify that as the precipitate?
e. Write the molecular, total ionic, and net ionic equations for the reaction of calcium hydroxide and sulfuric acid.
Conductivity Demos
15) a. Write a dissociation equation for calcium hydroxide.
b. Show how sulfuric acid ionizes.
c. Write the net ionic equation for the reaction of rubidium hydroxide and sulfurous aicd.
d. Give 3 different examples of solutions that would conduct electricity poorly.
e. Classify the following compounds as either ionic or covalently bonded: C 6H12O6, NaCl, Al(OH)3, candle wax
(C30H62), H2SO4, and HC2H3O2
i. Which of the solid substances from this list would ionize when dissolved in water?
ii. Which of the substances would act most similar to H3PO4 when dissolved in water?
iii. Which of the substances would not dissociate or ionize at all in water? Why?
iv. Which solutions would conduct electricity? Why?
v. Explain what effect, if any, ionic concentration would have on a salt solution’s electrical conductivity.
f. For each of the following, pick the solution that would conduct electricity the best.
i. 0.100M NaCl and 0.100M BaCl2
ii. 0.100M NaCl and 0.150M NaCl
iii. 0.100M HCl and 0.100M HNO2
iv. 0.100M HSO3 and 0.100M HC2H3O2
v. 0.100M KOH and 0.100M C6H6
Expt. #25 – “Acid/Base Titration”
16) a. Data was collected from an acid – base titration. Calculate the concentration of the
following lab data.
final volume of acid:
initial volume of acid:
final volume of base:
initial volume of base:
Volumes (+/- 0.05 mL)
14.88 mL
0.50 mL
46.12 mL
0.00 mL
Concentration of acid:
Amount of indicator:
Unknown base is NaOH
unknown base from the
0.350 M HCl
4 drops
b. If 0. 65 grams of a solid monoprotic acid was neutralized by 14.29 mL of 0.250 M NaOH, what is the molar mass of
the solid acid?
Expt. #26 – “Acid-Base Indicators”
17) a. How would you prepate 10 mL of 0.010 M HCl from a 0.10 M solution of HCl?
b. How would you make 500.0 mL of a 0.0500M HCl solution from a 1.00M HCl stock solution.
c. Given the data table below, determine the pH of a 0.1 M solution of acetic acid if adding methyl orange turns the
acetic acid solution red and adding orange IV turns the acetic acid solution light yellow.
Solution
Orange IV
Methyl Orange
0.1 M HCl
Pink
Red
0.01 M HCl
Light pink
Red
0.001 M HCl
Light yellow
Red
0.0001 M HCl
Light yellow
Orange
d. If the [H=} of a 0.200 M solution of a weak acid is 1.85, what’s the Ka of the acid?
e. If the Ka of a weak acid is 2.7 x 10 -6, what’s the pH of a 0.100 M solution of this acid?
f. What is the Ka of Methyl orange (given the data above)?