Name_________________________________________
Date______________
Period_________
Ch 1 & 2
These 3 questions refer to Substance Q, for which the solubility of Q is 99.2 g/100 g water at 50.0°C.
1. How many grams of water are needed to dissolve 43.7 g of Q at this temperature? [ANS = 44.1 g]
2. The solution in (3), above, is cooled to 20.0°C, where the solubility of Q is 75.5 g Q/100 g water.
How much Q crystallizes out of solution? [ANS = 10.4 g crystallizes since 33.3 g can dissolve @ 20°C]
3. A homogenous solution of substance Q is made from 29.0 g of Q and 35.0 g water at 50°C. The
solution is (unsaturated, saturated, supersaturated)? [ANS = unsaturated since 34.7 g Q could dissolve
in 35.0 g H2O at 50°C]
When the temperature drops 12.2 degrees Centigrade (Celsius) what is the final temperature (in
degrees Fahrenheit) if the starting temperature was 14.3 degrees Fahrenheit? [ANS = -7.65°F, go into
°C then subtract 12.2°C then go back to °F]
The circumference of the earth is about 2.50 x 104 miles. What is the approximate radius of the earth in
kilometers based on the information provided? (1 mile = 1.609 km) [4.02 x 104 km]
A student was asked to find the density of an unknown liquid. The following measurements were made
in a laboratory at 20oC. The student saw 71.000g on the balance when weighing the flask and stopper
empty, but wrote down 71 g rather than recording all of the zeroes.
Mass of empty flask plus stopper:
Mass of stoppered flask plus liquid:
Volume of “calibrated” flask:
71 g
128.125 g
63.021 mL
Be sure to use the correct number of “significant figures” according to the student’s results.
1. Calculate the density of the liquid using the data in the box above. [ANS = 0.91 g/ml]
2. What is the density of the unknown liquid when using the more precise value of 71.000 g
for the first measurement? [ANS = 0.90644 g/ml]
Suppose a student has copper (II) nitrate and Fe(NO 3)3 in her unknown sample in the Paper
Chromatography lab in this course. She identifies them using her known solutions, and calculates
the Rf values for each metal ion. The solvent moves 7.2 cm during the experiment. The R f value
for the copper (II) nitrate is 0.46.
1. What is the formula for copper (II) nitrate?
2. What is the name for Fe(NO3)3 ?
3. The Fe ion traveled 5.3 cm up the paper during the experiment. What was its Rf value?
4. How far did the copper ion travel up the paper during the experiment?
5. If the experiment had been carried out twice as long, with taller filter paper, which of the
following would be true?
(a) Both Rf values would increase and the ions would be further apart at the end.
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(b) Both Rf values would decrease and the ions would be closer together at the end.
(c) The ions would be further separated because the larger Rf value would get bigger and
the smaller Rf value would get smaller.
(d) The Rf values would remain constant and the ions would be further apart.
(e) The Rf values would remain constant and the ions would be closer together.
[ANS = Cu(NO3)2, iron(III) nitrate, 0.74, 3.3 cm, d]
The solubility of Li2SO4 is 31 g/100 g H2O at 80ºC and 35 g/100 g at 20ºC. The
solubility of KCl is 67 g/100 g H2O at 80ºC and 32 g/100 g at 20ºC. Water at 80ºC is
saturated with both at 80ºC and then cooled to 20ºC. Which precipitates? [ANS = KCl]
Consider the following lab data used to find the density of an unknown solid sample
Density Methanol = 0.791 g/ml
Mass Flask + Stopper = 107.25 g
Mass Flask + Stopper + Methanol = 154.47 g
Mass Flask + Stopper + Solid = 132.42 g
Mass Flask + Stopper + Solid+ Methanol = 176.12 g
a) What is the volume of the flask?
b) What is the density of the solid? [ANS = 59.7 ml, 5.6 g/ml]
How many grams of water are required to dissolve a mixture made from 18 g of A
(solubility = 14 g A/100 g water) and 23 g of B (solubility = 25 g B/100 g water),
assuming the solubilities are independent of each other? [ANS = 128.6 g water]
What is the density of a liquid which, when measured in a flask that holds 50.00 mL,
weighs 43.225 g? [ANS = 0.8645 g/ml]
Calculate the density (g/cm3) of a plastic cube that is 5.00 cm on a side and has a
mass of 203.75 g. [ANS = 1.63 g/cm3]
A saturated solution of compound Q is produced by dissolving 17.5 g of Q in 50.0 g of
water. What is the solubility of Q in grams Q per 100.0 g of water? [ANS = 35.0 g]
The density of a certain vegetable oil is 0.855 g/cm3. When placed in a beaker with
water, which (water or oil) will settle to the bottom of the beaker? [ANS = water]
What is the value of absolute zero (-273.15°C) in Fahrenheit? [ANS = -459.67°F]
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Calculate (2.36 – 0.899)*5.445 to the proper number of sig fig’s. [ANS = 7.96]
Compound A has a solubility of 22.0g/100g water at 27°C and 45.0g/100g at 75°C.
1. How much water is needed to dissolve 48.0 g of the compound at 27°C?
2. A 35.0 g sample of A is added to 85.0 g of water at 75°C. The solution is then
cooled to 27°C. How many grams of A will crystallize out?
[ANS = 218 g H2O, 16.3 g A]
The number of significant figures in the answer to (51.5 – 2.67) x (33.42 – 0.124) is
[ANS = 3 , 1.63 x 103]
Which of the following has the largest volume? 1 cup = 225 mL [ANS = D]
A) 2/3 cup
B) 150 mL
C) 3.78 x 10-2 cup
D) 0.75 cup
An infant ibuprofen suspension contains 100mg/5.0 mL suspension. The
recommended dose 10 mg/kg body weight. How many mL of this suspension should
be given to an infant weighing 18 lb? (Assume 2 significant figures). 1 lb = 453.6 g
[ANS = 4.1 ml]
A student made the measurements below in order to obtain the density of an unknown
solid. In the experiment, the volume of the flask was determined by finding the mass
of ethanol required to completely fill the empty flask.
Mass of flask + stopper = 29.245 g
Mass of flask + stopper + ethanol = 48.639 g
Density of ethanol = 0.789 g/mL
Mass of flask + stopper + solid = 54.623 g
Mass of flask + stopper + solid + ethanol = 71.776 g
1. What is the volume of the flask?
2. What is the mass of the unknown?
3. What is the volume of the unknown?
4. What is the density of the unknown?
[ANS = 24.6 ml, 25.378 g, 2.9 ml, 8.8 g/ml]
An empty flask weighs 65.228 g. The flask is completely filled with water, and the
mass of the flask and water is measured at 98.002 g. If the density of water is 0.9987
g/mL, calculate the volume of the flask. [ANS = 32.82 ml]
Solute A has a solubility of 22 g/100 g H2O. How many grams of A should be added to
78 g of water to make a saturated solution? [ANS = 17.2 g A]
How many 81 mg tablets can be made from 1.21 kg aspirin? [ANS = 14,938 tablets]
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A plastic block is 2.2 cm x 3.0 cm x 1.5 cm and has a mass of 12.4 grams. Will the
block float in water and why? (density of water = 1.00 g/mL) [ANS = c]
a) No, the density of block is 0.80 g/mL which is greater than the density of water.
b) Yes, the density of the block is 1.3 g/mL which less than the density of water.
c) No, the density of block is 1.3 g/mL which is greater than the density of water.
d) Yes, the density of the block is 0.80 g/mL which is less than the density of water.
e) none of the above
The solubility of sucrose at 20°C is 204 g/100 g of water and at 100°C is 487g/100 g.
A solution at 100°C is prepared by dissolving 245 g of sucrose in 77.0 g of water. The
solution is cooled to 20°C. How many grams of sugar crystallizes? [88 g]
A student made the measurements below in order to obtain the density of an unknown
solid. In the experiment, the volume of the flask is determined by finding the mass of
mercury (a dense liquid) required to completely fill the empty flask.
Mass of flask + stopper = 49.5770 g
Mass of flask + stopper + mercury = 182.2263 g
Density of mercury = 13.5939 g/mL
Mass of flask + stopper + solid = 131.2896 g
Mass of flask + stopper + solid + mercury = 205.1045 g
1. What is the volume of the flask?
2. What is the mass of unknown solid?
3. What is the volume of the unknown solid?
4. What is the density of the unknown solid?
[ANS = 9.75800 ml, 81.7126 g, 4.32800 ml, 18.8800 g/ml]
A solution is 12.0% of sodium hydroxide by mass and has a density of 1.131 g/mL.
What volume of this solution (in mL) contains 3.50 g of sodium hydroxide?
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Ch 3
A solution is made of 0.50 mol table salt (NaCl) and 0.50 mol water. What is the mass
percent water in the solution? [ANS = 23.6%]
What is the mass percent oxygen in (NH4)2CO3 •10H2O? [ANS = 75.4%]
What is the simplest formula of a compound containing only hydrogen and nitrogen,
which is 12.6% hydrogen by mass? If the substance has a real molar mass of 32
g/mol, what is its molecular formula? [ANS = Simplest is NH2, molecular is N2H4]
For a given reaction, the actual yield is 63.0 g. If this represents 66.0% of the theoretical yield, what is
the theoretical yield? [ANS = 95.5 g]
Suppose that, instead of carbon-12, fluorine-19 had been chosen as the basis for atomic masses. If it
were assigned a mass of exactly 10.000, what would the atomic mass of iron be? [ANS = 29.4 g/mol]
If the molar mass of a compound is 180.16 g/mol, and its empirical formula is CH2O,
what is its molecular formula? [ANS = C6H12O6]
How many H atoms in a cup (8 fluid ounces at 28.4 mL/ounce) of CH3OH? Density = 0.7918 g/mL [ANS
= 1.35 x 1025]
What is the mass of 18.3 moles H2SO4? [ANS = 1,794.8 g]
The density of ethanol, C2H5OH, is 0.789 g/mL. 45.6 mL of ethanol are burned to produce CO 2 and
water. How many grams of water are produced? [ANS = 42.2 g]
C2H5OH(l) + 3O2(g)  2CO2(g) + 3H2O
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Tartaric acid is the white, powdery substance that coats sour candies such as Sour Patch Kids. It
contains the elements H, C, and O. Combustion analysis of a 12.01 g sample of tartaric acid produced
14.08 g CO2 and 4.32 H2O.
Calculate the number of mols and mass of H.
Calculate the number of mols and mass of C.
Calculate the number of mols and mass of O.
What is the simplest formula of "tartaric acid"?
[ANS = 0.48 g H, 0.48 mol H, 3.84 g C, 0.32 mol C, 7.69 g O, 0.48 mol O, C2H3O3]
Consider the following balanced equation. How many mols of SO2 needed to produce 165 grams of S?
2 H2S(g) + SO2(g)  3 S(s) + 2 H2O(g)
One of the major components of beeswax has the formula C 56H118O2 (MM = 824 g/mol). Suppose a 1
lb (435g) candle made of that compound is lit and burns producing carbon dioxide and water. It is
placed in a small, sealed room that contains 66 mols of oxygen in the air and left to burn. Does the
candle burn completely or is the oxygen in the room consumed first?
1. Write a balanced chemical equation for the burning of the wax.
2. How many mols wax are in the candle?
3. How many mols oxygen are required to completely burn the candle?
4. Is wax or oxygen left over and how many mols of it remain?
Consider the reaction between Si and nitrogen for the formation of Si3N4(s).
3Si(s) + 2N2(g)  Si3N4(s)
15 grams of Si and 25 grams of nitrogen are reacted to form Si3N4(s).
1. If 15 g of Si reacts with excess N2 , how many moles of Si3N4 are produced?
2. If 25 g of N2 reacts with excess Si, how many moles of Si3N4 are produced?
3. If 15 g of Si and 25 g of N2 are reacted, how many moles of Si3N4 can be formed if
the percentage yield is 85%? [ANS = 0.178 moles, 0.446 moles, 0.151 moles]
Consider potassium chlorate KClO3 (MM = 122.6 g/mol).
1. How many oxygen atoms are there in 5.43 grams of potassium chlorate?
2. How many grams of potassium are there in 3.45 grams of potassium chlorate?
Suppose fluorine were used as the basis of atomic mass, and assigned a mass of
9.00. What would the atomic mass of copper be when using this basis?
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Period_________
What is the simplest formula for the compound C6H12O6?
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Consider the unbalanced reaction:
__CH3NH2(g) + __O2(g) → __N2(g) + __H2O(g) + __CO2(g)
Once balanced, what is the sum of coefficients for the products (use
smallest whole number coefficients)? [16, balanced rxn coefficients are 4,9,2,10,4]]
If the actual yield of a reaction is 68.2 % and 15.5 g of product forms, what is the
theoretical yield? [22.7 g]
The compound C6H12O2N has half as many grams of carbon as hydrogen (Y or N)?
[No, has 72 g C and 12 g H, it has half as many moles of C as H]
What is the mass, in grams, of 6.52 x 1021 molecules of aspirin, C9H8O4? [1.95 g]
What is the mass percent of O in a compound with a formula C7H5(NO2)3
(MM = 227.14 g/mol)?
Lead (II) oxide reacts with ammonia as follows:
3PbO(s) + 2NH3(g)  3Pb(s) + N2(g) + 3H2O(l)
1. How many grams of PbO are consumed in the reaction of 8.16 g PbO?
(MM of PbO is 223.2 g/mol)
2. If 0.312 g of NH3 is available to react with 8.16 g PbO, how many grams of
Pb are produced?
3. If the actual yield is 4.95 g Pb, what is the percent yield?
[ANS = 0.415 g, 5.69 g, 87%]
Benzocaine is a compound containing carbon, oxygen, hydrogen and
nitrogen. When a sample of benzocaine weighing 3.54 g is burned in excess
oxygen, 8.49 g of CO2 and 2.14 g of H2O are formed. In a separate experiment, the
percentage of N is determined to be 8.468 %.
1. How many grams of carbon are in the sample?
2. How many grams of hydrogen are in the sample?
3. How many grams of nitrogen are in the sample?
4. How many grams of oxygen are in the sample?
5. What is the simplest formula?
[2.32 g C, 0.239 g H, 0.300 g N, 0.681 g Ox, C9H11O2N)
An oxide of a metal, Q, has the formula QO4. The oxide reacts with excess H2 to yield
the free metal and H2O according to the following balanced reaction.
QO4(s) + 4H2(g)  Q(s) + 4H2O(l)
1. A 11.29 g sample of QO4 yields 3.198 g of H2O. How many moles H2O produced?
2. How many moles of QO4 are consumed?
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3. What is the molar mass of QO4?
4. What is the atomic mass of Q?
5. What element is Q?
(0.1775, 0.04437, 254.5, 190.5, Os)
In determining the simplest formula of vanadium oxide, 4.3498 g of vanadium are
placed in a crucible with 4.010 grams of oxygen which is in excess.
When the reaction is complete, the product has a mass of 7.7656 grams.
1. How many moles of vanadium are there in the product?
2. How many grams of oxygen are there in the product?
3. How many moles of oxygen are there in the product?
4. Calculate the excess amount (in grams) of oxygen used in this experiment.
5. What is the simplest formula of vanadium oxide?
65 g of a compound containing C, H, and O is burned with excess oxygen. 166.28 g
CO2 and 68.04 g of H2O are formed. What is the simplest formula of the compound?
[C5H10O]
0.35 g of a C, H, N containing compound is burned in excess oxygen. 0.6695 g CO 2
and 0.5478 g H2O are formed. What is the simplest formula of the compound?
[C2H8N]
A compound has a ratio of Cr:O of 1.08 by mass. What is the simplest formula of the
compound? [ANS = CrO3]
0.150 g of a compound containing C, H, N, Cl, and O is run through a series of reactions to isolate
each element. The C ends up in 0.138 g CO2 , the H in 0.0566 g H2O , the N in 0.017 g NH3 , and
the Cl in 0.3014 g AgCl. The O is never specifically isolated. What is the simplest formula of the
compound? [Answer: C3H6NCl2O]
A molecular compound contains 92.3% carbon and 7.7% H by weight. If 0.125 mol of
the compound weighs 3.25 g, what is its molecular formula?
A mixture containing 1.00 mole of NH3 and 1.80 mole of nitrogen oxide according to
4NH3(g) + 6NO(g)  5N2(g) + 6 H2O (ℓ)
a. What is the limiting reactant?
b. How many moles of N2 are produced?
c. How many moles of the reactant in excess remain?
d. If 0.800 moles of H2O are actually produced, what is the % yield of the reaction?
e. Write the name for NH3.
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Cyanogen gas, C2N2, has been found in the gases of outer space. It can react with
fluorine to form carbon tetrafluoride and nitrogen trifluoride.
C2N2(s) + 7F2(g)  2CF4(g) + 2NF3(s)
1. What is the molar mass of cyanogen?
2. How many moles are there in 320.0 g of fluorine gas, F2?
3. How many atoms are there in 5.00 g of carbon tetrafluoride?
4. How many grams of fluorine needed to produce 4.981 mol of nitrogen trifluoride?
5. A student is asked to make 10.00 g of the carbon tetrafluoride. He is told that the
reaction had a 80% yield. How many grams of cyanogen will he need to react with
an excess of fluorine gas?
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If S-32 were assigned as the standard for expressing relative atomic
masses and assigned an atomic mass of 10.00 amu, What would the
atomic mass of cobalt be using this basis?
What is the simplest formula for the compound C12H22O11?
Consider the unbalanced reaction:
__NaCℓ(g) + __SO2(g) + __H2O(g) + __O2(g) → __N2SO4(s) + __HCℓ(g)
Once balanced, what is the sum of coefficients for the products (use
smallest whole number coefficients)?
If the actual yield of a reaction is 88.2 % and 25.5 g of product forms, what is the
theoretical yield?
The compound C6H12O2N has half as many grams of hydrogen as carbon. (Y or N)
Copper has two naturally occurring isotopes. Cu-63 has an atomic mass of 62.9296
and an abundance of 69.17%. What is the atomic mass of the second isotope?
Calculate the average mass of a sodium atom in grams.
Citric acid has the formula, C6H8O7 (MM = 192.12 g/mol). How many hydrogen
atoms are there in 5.0 g of citric acid?
What is the mass percent of C in a compound with a formula (C5H5)2Fe?
0.150 g of a C, H, N, Cl, and Oxygen compound is burned in excess oxygen and
found to produce 0.138 g CO2 and 0.0566 g H2O. The nitrogen is isolated as NH3 and
0.017 g NH3 is obtained. The Cl is isolated as AgCl and 0.3014 g AgCl is obtained.
What is the simplest formula of the C, H, N, Cl, and Oxygen compound? [ANS =
C2H4NCl3O]
Hexamethylenediamine (MW = 116.2 g/mol), a compound made up of
carbon, hydrogen and nitrogen atoms, is used in the production of nylon. When
6.315 g of hexamethylenediamine is burned in oxygen, 14.36 g of carbon dioxide
and 7.832 g of water are obtained.
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1. How many grams of carbon are in the sample?
2. How many grams of hydrogen are in the sample?
3. How many grams of nitrogen are in the sample?
4. What is the simplest formula for hexamethylenediamine?
A strip of zinc metal is placed in an aqueous solution containing AgNO3
causing the following reaction to occur:
Zn(s) + 2AgNO3(aq) → 2Ag(s) + Zn(NO3)2(aq)
1. If 2.00 grams of zinc metal reacts with an excess of AgNO3, how many moles of
silver can be produced?
2. If 2.50 grams of silver nitrate reacts with an excess of zinc metal, how many moles
of silver can be produced?
3. If 2.00 grams of zinc metal and 2.50 grams of silver nitrate react, how many grams
of silver can theoretically be produced?
4. How many moles of the excess reactant remain after the complete reaction?
5. If the actual yield of Ag is 1.21 grams, what is the percent yield for the reaction?
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Ch 4
The concentration of NH4+ ions in a solution made from 0.30 mol (NH4)2CO3
diluted to a total volume of 1.0 L is (GT, LT, EQ) 0.30 M.
Complete the following half reaction:
CH3OH(aq) + 2OH-(aq)  CH2O(aq) + ___ + 2H2O
What is the oxidation number of iron in Fe3O4?
How many moles Na2CO3 are needed to react completely with 0.450 L 0.100 M HCl?
You have two bottles with clear, colorless aqueous solutions marked A and B. One
contains NaCl and the other contains Na3PO4. To determine which is which, you take
a small sample from bottle B, mix it with a small sample of Ca(NO3)2 (aq) and a
precipitate forms. Bottle B contains?
Consider the reactions below
A. H+ + OH- → H2O
B. F- + H2O → HF + OH
C. Mg+2 + OH- → Mg(OH)2
D. HF + OH- → H2O + F
E. NH3 + H+ → NH4
Write the capital letter for the equation above that represents:
(a) a precipitation reaction
(b) reaction of a weak base with water
(c) net ionic equation for a strong acid and strong base reaction
(d) reaction between a weak base and a strong acid
(e) reaction between a weak acid and strong base
2. Consider separate sol’ns of soluble compounds, Na3PO4, FeCl3, (NH4)2CO3 .
Write formulas for all insoluble compounds that can be formed by mixing these sol’ns.
A 2.50 L solution of K2CrO4 is prepared by dissolving 8.75 g K2CrO4 in water.
(a) What is the molarity of the solution?
(b) What is the molarity of the potassium ions in the solution above?
(c) Potassium chromate, K2CrO4, was used as an indicator for the end point of the
titration of an unknown chloride with silver nitrate solution. Silver chromate,
Ag2CrO4, is an insoluble solid. Write a net ionic equation for reaction of silver ion
and chromate ion to form solid silver chromate. Indicate states.
(d) Suppose that 0.40 mL of 0.50 M K2CrO4 solution was used as the indicator. What
volume of 0.15 M silver nitrate solution is needed to react completely with this
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amount of K2CrO4 indicator?
6 g of Al (s) reacts with excess hydrochloric acid. How many liters of wet gas will be
produced @ a total pressure of 1 atm at 298 K? (vapor pressure of water at 298 K is
23.76 mm Hg) [ANS = 8.425 L (is 0.3336 moles H2)
What volume of 0.3 M NH3 will completely neutralize 25 ml of 0.1 M H2SO4?
[ANS – 16.67 ml]
What mass of precipitate will form if 65 ml of 0.2 M Ba(OH)2 solution reacts with
excess Co(NO3)3 solution? [ANS = 0.953 g]
For the balanced redox reaction run in acid solution:
12H+(aq) + 2IO3-(aq) + 10I-(aq)  6I2(aq) + 6H2O
82 ml of 0.43M KI solution is mixed with 55 mL of 0.97 M potassium iodate solution.
1. If 82 mL of 0.95 M KI reacts with excess KIO3, how many moles I2 produced?
2. If 55 mL of 0.42 M KIO3 reacts with excess KI, how many moles I2 produced?
3. If 82 mL of 0.95 M KI and 55 mL of 0.42 M KIO3 react, how many moles I2 can be
produced?
4. What is the concentration of iodine in the resultant solution? (Volumes additive)
A sample of a chloride salt weighing 484.6 mg is titrated with AgNO3 using K2CrO4
as indicator. To reach the end point a 52.3 mL of 0.1475 M of AgNO3 solution is
required. How many moles of chloride were in that sample?
A sample of weak acid, HB, is titrated with 43.21 mL of 0.1122 M KOH for
neutralization to a phenolphthalein end point. How many moles HB in the sample?
A 0.432 g sample of a weak base is titrated to an appropriate end point with 25.53 mL
of 0.1555 M HNO3.
1. How many moles H+ were used?
2. How many moles base were in the sample?
3. What is the molar mass of the weak base?
The iron content of a sample can be determined by titration with potassium
permanganate in acid. The oxidation and reduction half reactions which are involved
in this titration are given as follows:
8H+ (aq) + MnO4 - (aq) + 5e-  Mn2+ (aq) + 4H2O
Fe2+ (aq)  Fe3+ (aq) + e1. How many moles of Fe2+ can be oxidized to Fe3+ by 1.75 x 10-2 mol of MnO4-?
2. What is the mass of iron in the sample?
3. If the sample containing iron weighed 7.265 g, what is the % iron in the sample?
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Date______________
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Answer the questions below, using LT, GT, EQ, or MI (for more information required).
2. The oxidation number of Cℓ in CℓO4- is the oxidation number of Cℓ in CℓO3- is?
3. The volume of 0.100 M NaOH needed to react completely with 25.0 mL of
0.100 M H2SO4 is __ than 25.0 mL.
5. The concentration of OH- in a solution of 0.15 M NH3 (aq) is __ 0.15 M.
2. The oxidation number of O in Na2O2 is __ the oxidation number of O in O2.
4. The number of s electrons in Fe3+ is __ 8.
5. The concentration of H+ in one liter of 0.15 M HNO2 is ___ 0.15.
When aqueous solutions of barium hydroxide and iron (III) nitrate are
mixed, a red precipitate forms:
Fe3+ (aq) + 3OH- (aq)  Fe(OH)3 (s)
What is the mass of the precipitate when 50.00 mL of 0.200 M Ba(OH)2 is mixed with
an excess of 0.125 M Fe(NO3)3?
Laundry bleach is a solution of sodium hypochlorite (NaClO). To determine the
hypochlorite (ClO-) content of bleach (which is responsible for its bleaching action),
sulfide ion is added in basic solution. The balanced equation for the reaction is ClO(aq) + S2-(aq) + H2O Cl-(aq) + S(s) + 2OH-(aq) The chloride ion resulting from the
reduction of NaClO is precipitated as AgCl. When 50.0 mL of laundry bleach (d = 1.02
g/mL) is treated as described above, 4.95 g of AgCl is obtained.
1. How many moles of AgCl precipitated?
2. How many moles of OCl- ions are present?
3. What is the mass percent of NaClO in the bleach sample?
When solutions of K2CO3 (aq) and Mg(NO3)2 are mixed, a precipitate of _____ forms.
Write the balanced net ionic equation for the following reaction: An aqueous solution
of magnesium chloride is added to an aqueous solution of silver nitrate. What are the
spectator ions?
Calculate the concentration of a solution made by dissolving 10.0 g of
sodium chloride, NaCl, in 750.0mL of solution
A 50.00 mL of 0.200 M iron (III) nitrate is mixed with 0.400 M calcium hydroxide. What
is the minimum volume of calcium hydroxide required to completely precipitate iron
(III) hydroxide?
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Calculate the concentration of perchlorate ions in solution after 24.7 mL of 1.72 M
HClO4 is added to 19.2 mL of 1.79 M KOH and the resulting solution is diluted to 500.0
mL with water.
If 50 ml of 0.1 M Ca(NO3)2 is mixed with 62 ml 0.05 M Na3PO4,
How many grams precipitate will form? [ANS = 0.48 g]
What will final concentration of excess reactant ion be? [ANS = 0.0031 M]
Calculate the concentration of HCl if 25. 0 mL of the acid solution is titrated with 19.6
mL of 2.10 M Ca(OH)2 to produce CaCl2 and water.
Consider the following reaction:
2K(s) + 2H2O _ 2KOH(aq) + H2(g)
1. The oxidizing agent is ________.
2. The base is ______.
3. The number of electrons involved in the oxidation half reaction is _____. (use
smallest whole number coefficients)
4. Which element is reduced? _____.
Consider the following unbalanced oxidation-reduction reaction in acid solution.
Answer the following questions:
H3PO2(aq) + Cr2O72-(aq) _ H3PO4 (aq) + Cr3+(aq)
1. Label the oxidation numbers to the elements indicated in following species:
H3PO2 P: _____ O: _____
Cr2O7 2- Cr: _____
H3PO4 H: _____ P: _____
Cr3+ Cr: _____
2. Which element is reduced?
3. Which is the reducing agent?
4. Write and balance both half reactions in acid solution.
5. How many electrons are transferred in overall reaction?
6. How many moles of H+ ions are involved in the overall balanced reaction?
A solid sample containing some Fe2+ ion weighs 1.000 g. It requires
75.52 mL 0.0205 M KMnO4 to titrate the Fe2+ in the dissolved sample to a pink end
point. Consider the following net ionic equation for the reaction between MnO4- ion
and Fe2+ ion in acid solution is
8H+(aq) + 5Fe2+(aq) + MnO4-(aq) _ 5Fe3+(aq) + Mn2+(aq) + 4H2O
1. How many moles of MnO4- ion are required in the reaction?
2. How many moles of Fe+2 are there in the sample?
3. How many grams of iron are there in the sample?
4. What is the percentage of Fe in the sample?
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Complete and balance the following chemical equations if a reaction occurs. If no
reaction occurs, write "No reaction".
I-(aq) + Cl2(aq) 
Br-(aq) + I2(aq) 
What is the hydroxide ion molarity of a solution obtained by adding 13.0 g of NaOH to
795 mL of a 0.200 M solution of Sr(OH)2? Assume no volume change after NaOH is
added.
A 12.00 g sample of pure tartaric acid, C4H6O6, (MM = 150.08 g/mol) requires 186.6
mL of 0.857 M potassium hydroxide for complete reaction. How many moles of
hydroxide ion are required to neutralize one mole of tartaric acid?
A solution is prepared by mixing 0.100 L of 0.120 M sodium chloride with 0.230 L of a
0.180 M MgCl2 solution. What volume of a 0.200 M silver nitrate solution is required to
precipitate all the Cl- ion in the solution as AgCl?
To titrate a 5.00 mL sample of a saturated aqueous solution of sodium
oxalate, Na2C2O4, requires 25.82 mL of 0.02140 M KMnO4 (aq). The balanced
equation for the reaction is
5C2O42-(aq) + 2MnO4-(aq) + 16H+(aq) � 2Mn2+(aq) + 8H2O(l) + 10CO2 (g)
1. What is the molarity of sodium oxalate solution?
2. How many grams of sodium oxalate would be present in 250.0 mL of the saturated
solution?
The number of moles of HCℓ in 10 mL of 12 M HCℓ is equal to that
in 1000 mL of 0.012 M. (Yes or No)
2. Solutions of silver sulfate and barium chloride are mixed. Write the formula of the
precipitate(s) that form(s). If no precipitate forms, write NR.
3. Classify HCℓO3 as strong acid, weak acid, strong base or weak base
4. C6H5NH2 is an Arrhenius acid when added to water? (Yes or No)
5. Acetic acid and sodium hydroxide are combined. What are the spectator ion(s)?
Write the net ionic equations for the reactions between aqueous solutions of the
following compounds. (Do not forget to indicate the physical states)
1. HCN(aq) and KOH(aq)
2. Na3PO4(aq) and Ba(OH)2(aq)
3. NH3(aq) and HCℓ(aq)
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Ten milliliters of a 0.250 M solution of Aℓ2(CO3)3 is mixed with 25.0 mL of a 0.012 M
solution of K2CO3.
1. How many moles of CO32- ions are present in the final mixture?
2. What is the molarity of CO3
2- ions in the final solution? (Assume the volumes are additive)
A sample of limestone weighing 1.005 g is dissolved in 75.00 mL of 0.2500 M
hydrochloric acid. The following reaction occurs: CaCO3(s) + 2H+(aq) → Ca2+(aq) +
CO2(g) + H2O(l) It is found that 18.50 mL of 0.150 M NaOH is required to titrate the
excess HCℓ left after reaction with the limestone.
1. How many moles of hydrochloric acid are used ?
2. How many grams of CaCO3 (MM = 100.09 g/mol) are there in the sample?
3. What is the mass percent of CaCO3 in the limestone?
E. What is the volume of 0.2500 M cobalt (III) sulfate, Co2(SO4)3, required to react
completely with 11.20 mL of 1.45 M sodium carbonate to form cobalt (III) carbonate?
Three experiments are performed:
(A) Ca(OH)2 is mixed with HF.
(B) NaOH is mixed with Mg(NO3)2
(C) Cu reacts to form Cu2+.
Write the letter of the experiment(s) that answers each of the following questions. If
none of the experiments applies, write NONE.
1. Which experiment involves a strong acid?
2. Which experiment produces a precipitate?
3. Which experiment involves a strong base?
4. Which experiment involves Cu as an oxidizing agent?
5. Which experiment produces water as a product?
Iodine reacts with thiosulfate ion, S2O32-, to give iodide ion and the tetrathionate ion,
S4O6 2-. The balanced equation for the reaction that takes place is
I2(aq) + 2S2O3 2-(aq) → 2I-(aq) + S4O6 2-(aq) If 25.0 g of iodine is dissolved in enough
water to make 1.50 L of solution, what volume of 0.244 M sodium thiosulfate will be
needed for complete reaction?
A student weighs out 0.1965 grams of an unknown chloride into an
Erlenmeyer flask and titrates it with AgNO3 using K2CrO4 as indicator. To reach the
endpoint, 17.24 mL of 0.1529 M AgNO3 is required.
1. What is the number of moles of chloride ion in the sample?
2. What is the mass of chloride in the sample?
3. Calculate the mass percent Cℓ- ion in the sample.
4. If the student read the molarity of the AgNO3 as 0.1259 M instead of the correct
value, would the calculated mass percent Cℓ- be LESS than or GREATER than or
the SAME as (CIRCLE ONE) the actual value.
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5. If the student was past the endpoint of the titration when he took the final buret
reading, would the calculated mass percent Cℓ- be LESS than or GREATER than
or the SAME as (CIRCLE ONE) the actual value.
A 0.100 g sample of an unknown acid requires 12.95 mL of 0.0857 M NaOH for
neutralization to a phenolphthalein end point. What is the molar mass of the
unknown acid? HA(aq) + OH-(aq) → 2H2O + A-(aq)
It is determined that the halogens rank as oxidizing agents in the following manner:
(weakest) I2, Br2, Cℓ2 (strongest). Write R if a reaction occurs, NR if no reaction occurs,
and MI if more information is required.
Br2 solution + Br- solution
Br2 solution + Cℓ- solution
Br2 solution + I- solution
Consider the following balanced redox reaction. The reaction is the basis for the
permanganate titration used to determine the % Fe in a sample.
8H+(aq) + MnO4-(aq) + 5Fe2+(aq) → Mn2+(aq) + 5Fe3+(aq) + 4H2O 2.1 g of an
unknown iron salt are dissolved in water, acidified with H3PO4 and titrated with a
standardized KMnO4 solution. A persistent pink color is observed after 7.8 mL of a
0.250 M KMnO4 solution are used.
1. How many moles of MnO4- are used in the titration?
2. How many moles of Fe are present in the sample?
3. What is the mass percent of Fe in the sample?
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Ch 5
Answer the questions below, using LT (for is less than), GT (for is greater
than), EQ (for is equal to), or MI (for more information required)
1. The volume of one mole of hydrogen gas at STP is __ the volume of one mole of
argon gas at STP.
3. A mixture of gases contains 3 mol Kr, 2 mol Ar and 2 mol Ne. The mole
fraction of Kr is __ the mole fraction of Ar.
1. Two tanks of equal volume contain hydrogen and nitrogen, respectively.
2, At the same temperature, the pressure inside the hydrogen tank is ____
the pressure in the nitrogen tank._______
4. The mole fraction of chlorine in a mixture of gases is 0.40. The total of the
mole fractions of the other gases in the mixture is ____ 0.60.
1. After the pressure of one mole of gas is tripled (at constant temperature), its volume
is three times greater than its original value.
2. The partial pressure of water vapor in a gas collected over water is
independent of the temperature.
3. A molecule of He at 100 ºC and 1 atm pressure will have exactly the same speed
as a molecule of N2 at the same temperature and pressure.
4. At a constant temperature and pressure, CH4 gas will effuse twice as fast as SO2
gas.
5. You are given two tanks of equal volume, each at the same temperature and
pressure. One contains H2 and the other He. The tank containing the hydrogen has a
larger number of molecules than the one containing helium.
If 0.0129 mol of N2O4 (MM = 92.02 g/mol) effuses through a pinhole in a
certain amount of time, how many moles of NO (MM = 30.01 g/mol) would effuse in
that same amount of time under the same conditions? [Ans = 0.0226 moles]
You have three tanks of gas, all of equal volume and at equal temperature: Tank A
has 1.00 mol CH4, Tank B has 1.00 mol He and Tank C has 1.00 mol CO2. Use the
following terms to answer the questions below: GT (greater than), LT (less than), EQ
(equal to) or MI (more information needed).
1. The pressure in Tank B __ the pressure in Tank C.
2. The average kinetic energy of the molecules in Tank A ___ the average
kinetic energy of the molecules in Tank C.
3. If an equal sized pinhole is made in each, the rate at which the pressure in
Tank A will drop is ____ the rate at which the pressure will drop in Tank B.
4. If the contents of Tank B are transferred without loss to a new tank of half
the volume, (at the same temperature) the new pressure in Tank B will be
__ the pressure in existing Tank C.
5. The average speed of the molecules in Tank A is ___ the average speed
of the molecules in Tank C.
6. The density of the gas in Tank B is ___ the density of the gas in Tank C.
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For questions 1- 4. Ammonia, NH3, is the most important commercial
compound of nitrogen. It can be produced by reacting nitrogen with hydrogen gas.
1. Ammonia is kept at 15°C in a 10.0 L flask with a pressure of 1.95 atm. What is the
pressure in the flask if the temperature is increased to 25°C?
2. Ammonia is stored in a cylinder with a movable piston at 25°C and 2.50 atm
pressure.
What is the pressure in the cylinder if the temperature is increased to 45°C and the
volume occupied by the gas is halved?
3. How many grams of ammonia are produced if 7.85 L of ammonia is collected at 15°C and 5.93 atm pressure?
4. What is the density of ammonia at 32°C and 745 mm Hg?
Methanol, CH3OH, can be synthesized by the following reaction:
CO(g) + 2H2(g)  CH3OH(g)
How many moles of hydrogen gas, measured at a temperature of 355 K and a
pressure of 738 mm Hg, is required to synthesize 2.32 moles of methanol?
A 1.58 g sample of C2H3X3 (g) has a volume of 297 mL at 769 mm Hg and 35ºC. What
is the atomic mass of element X? [ANS = 35ish, so Cl]
Consider two bulbs connected by a valve. Bulb A has a volume = 200.0 mL &
contains nitrogen gas at a pressure of 0.500 atm. Bulb B has a volume of 0.785 L &
contains CO gas at a pressure of 1.40 atm. What is the pressure in the two tanks after
the valve is opened? The volume of the connecting tube & valve is negligible. Nitrogen
doesn’t react with carbon monoxide. (Temperature stays constant) [ANS = 1.22 atm]
A student weighs an empty flask and stopper and finds the mass to be 55.441g. She
then adds excess unknown liquid and heats the flask in boiling water bath at 100oC.
After all the liquid is vaporized, she removes the flask from the bath, stoppers it, and
lets it cool. After it is cool, she momentarily removes the stopper, then replaces it and
weighs the flask and condensed vapor, obtaining a mass of 56.513 grams. The
volume of the flask is 215.8 mL. The barometric pressure in the laboratory that day
was 752 mm Hg. What is the molar mass of the unkown in the flask?
Answer the following questions. A flask at room temperature contains exactly equal
amounts (in moles) of nitrogen and chlorine.
1. Which of the two gases exerts the greater pressure?
2. The molecules or atoms of which gas have the greater average velocity?
3. The molecules of which gas have the greater average kinetic energy?
4. If a small hole were opened in the flask, which gas would effuse more quickly?
A sealed balloon is filled with 1.00 L of helium at 23°C and 1.00 atm. The balloon rises
to a point in the atmosphere where the temperature is -31 °C and pressure is 220 mm
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Hg. What is the change in volume of the balloon as it ascends from 1.00 atm to a
pressure of 220 mm Hg?
An unknown gas has a density of 3.164 g/L at STP. What is the molar mass of the
gas?
Nitrogen can react with steam to form ammonia and nitrogen oxide gases.
A 20.0 L sample of nitrogen at 173°C and 772 mm Hg is made to react with an excess
of steam. The products are collected at room temperature (25°C) into an evacuated
flask with a volume of 15.0 L. What is the total pressure of the products in the 15.0 L
flask? The balanced equation for the reaction that takes place is:
5N2(g) + 6H2O(g) _ 4NH3(g) + 6NO(g)
A sample of neon effuses from a container in 76 seconds. The same
amount of an unknown gas requires 155 seconds, what is the molar mass of the
unknown the gas? [ANS = 84.1]
A flask with stopper weighs 62.93 g. About 5 mL of an unknown liquid is
added to the flask and it is heated in a boiling water bath at 100°C until the liquid has
completely evaporated. The flask is removed from the bath, stoppered, cooled, and
then air is admitted to the flask at an atmospheric pressure of 745 mm Hg. The mass
of the flask plus condensed vapor is 63.49 g and the flask's volume is 224.4 mL.
1. List the following parameters for the vapor of the unknown liquid at the moment
when the flask is removed from the boiling water bath. Write each answer with the
proper number of significant figures.
a. What is the pressure of the vapor in the flask in atm?
b. What is the volume of vapor in Liters?
c. What is the temperature of the vapor in Kelvin?
d. What is the mass of the vapor?
2. What is the molar mass of the unknown liquid? Give the answer in the proper
number of significant figures.
A gas in 2.0 L flask at 35°C has a pressure of 755 mm Hg. What is the pressure of the
gas in the same container if the temperature is increased to 75°C?
At what temperature will a molecule of uranium hexafluoride, the densest gas known,
have the same average speed as a molecule of the lightest gas, hydrogen, at 37°C?
How many liters of O2(g) measured at 295 K and 763 mm Hg are consumed in the
complete combustion of 2.55 L of dimethyl ether measured at 295 K and 478 mm Hg?
CH3OCH3(g) + 3O2(g) � 2CO2(g) + 3H2O(l)
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A quantity of N2 gas originally held at 4.75 atm pressure in a 1.00 L container at 20°C
is transferred to a 10.0 L container at 20°C. A quantity of O2 gas originally at 5.25 atm
and 20°C in a 5.00 L container, is transferred to this same container. What is the total
pressure in the new container?
What increase in the Celsius temperature will produce a 5.0% increase in the volume
of a sample of gas originally at 25.0ºC if the gas pressure held constant?
A compound has the simplest formula C2H2X2. A 256.0 mL flask, at 373 K and 740.0
mm Hg, contains 0.789 g of the gaseous compound. What is the atomic mass of the
unknown element, X? [ANS = 35.5, Cl]
A metal hydride, MH2 reacts with water per
MH2(s) + H2O(ℓ) M(OH)2 (s) + 2H2(g)
When 0.1232 g of MH2(s) reacts with water, 225.0 mL of dry H2(g) are produced at
16°C and 0.9870 atm pressure. Calculate the molar mass of MH2 & identify the metal
M. [ANS = 24 g, Mg]
Consider two different containers separated from each other by a valve.
Both containers are at the same temperature. Calculate the final pressure inside the
system after the valve connecting the two containers is opened. Ignore the volume of
the tube connecting the two containers.
Container A Container B Gas Ar O2 V 2.0 L 3.0 L P 1.0 atm 2.0 atm T 25ºC 25ºC
If a 0.0250 mol of NO effuses through a pinhole in a certain amount of time,
how much N2O4 would effuse in that same amount of time under the same conditions?
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Ch 6
The Rydberg formula for the energy levels of the electron in a hydrogen atom is
En = - RH/n2 where RH = 2.180x10-18 J.
The Brackett series includes transitions from nhi  nlo = 4.
1. What is the wavelength of the lowest energy transition of the Brackett series?
2. A line in the Brackett series (nlo = 4) occurs at 2624 nm. Calculate nhi for the
transition associated with this line.
Which of the following ions with electrons in their ground (lowest energy) states will
have MORE than one UNPAIRED electron? Ti+3, Ge+3, Cr+3?
A photon of light has a wavelength of 423 nm. (1 nm = 1 x 10-9 m)
1. What is the frequency of the light?
2. What is the energy associated with that wavelength in kilojoules per mole?
Consider a transition in an atom for which nlow = 1 and nhigh = 2. The energy of this
transition is calculated at 220 kJ/mol. The energy of the transition from n = 2 to n = 3
will also be 220 kJ/mol.
2. The energy of a photon of blue light (_ = 475 nm) is lower in energy than that of
one of red light (_ = 650 nm). T or F
3. The frequency of a wave is directly proportional to the speed at which the wave is
traveling. T or F
4. When n = _, H exists as H+.
What is the wavelength (_, in nm) of the light wave associated with a frequency of
4.62 x 1014 s-1?
Using the Bohr model, what is the energy (in J) associated with a transition from the n
= 2 to the n = 5 level
A helium-neon laser emits light at 632.8 nm. The bond enthalpy of IBr is 180 kJ/mol.
1. Does a helium-neon laser photon have enough energy to break that bond?
2. What is the enthalpy of the strongest bond which such a photon could break?
A laser in a compact disc player produces light with a wavelength of 780 nm. (1 m = 1
x 109 nm).
1. What is the frequency of the light?
2. What is the energy of this radiation in kilojoules per mole?
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Answer the questions below, using LT (for is less than), GT (for is greater
than), EQ (for is equal to), or MI (for more information required) in the blanks provided.
1. The wavelength of the photon required to promote an electron in the
hydrogen atom from the n = 2 to the n = 3 level is __(1)___ the
wavelength of the photon required to promote an electron in the
hydrogen atom from the n = 1 to the n = 2 level.
2. For a titanium atom in the ground state, the energy of the 3d sublevel
is __(2)__ the energy of the 4s sublevel.
3. The � quantum number of the 3d sublevel is __(3)___ the � quantum
number of the 5d sublevel.
4. The energy of the 3p orbital with m� = -1 is ___(4)___ the 3p orbital
with m� = +1 in a P atom.
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Ch 8
1. Two objects, a potato and a metal pan, are removed from a 450°F oven. If
the masses are equal, which will cool to room temperature more quickly
(take the specific heat capacity of the pan to be 0.335 J/g-C and that of the
potato to be about 4.18 J/g-C)? For the next four questions, consider a solution
prepared from 10.00 g of NaOH in enough water to make 1.00 L. 106 kJ of heat is
evolved.
2. When the solid is dissolved, the temperature of the solution rises. The
reaction is endothermic (true/false).
3. The sign of H for this process is ____________.
4. What is q for the dissolving of 2.50 g of NaOH to a total volume of 1.00 L?
5. What is q for the dissolving of one mole of NaOH?
B. (7 points) When 5.00 g of chromium at 23.00ºC absorbs 62.5 J of heat, the
temperature increases to 50.8ºC. What is the specific heat of chromium?
C. (8 points) Consider the following reaction for the combustion of propane, C3H8.
C3H8(g) + 5O2(g) � 3CO2(g) + 4H2O(g) ΔH = -2044 kJ
1. How many moles of propane are necessary to produce 6.12 x 10 5 kJ of heat?
2. How many moles of CO2 are produced if 1.5 x 103 kJ of heat is liberated?
(10 points) Zinc metal reacts with hydrochloric acid according to the following
balanced equation. Zn(s) + 2HCl(aq)  ZnCl2(s) + H2(g) When 0.103 g of Zn(s) is
combined with enough HCl to make 50.0 mL of solution in a coffee-cup calorimeter, all
of the zinc reacts, the temperature of solution changes from 22.5ºC to 23.7ºC. Assume
that the density of solution is 1.00 g/mL and specific heat of the solution is 4.18J/g·ºC.
1. What is the heat of the reaction?
2. What is the enthalpy change for the reaction written as above?
E. (6 points) Given the following reactions:
Ca(s) + 1/2O2(g) + CO2(g)  CaCO3 (s) ΔH = -812.8 kJ
2Ca(s) + O2(g)  2CaO (s) ΔH = -1269.8 kJ
What is ΔHreaction for the reaction below?
CaO(s) + CO2(g)  CaCO3(s)
(8 points) Consider the following thermochemical data:
2P (s) + 3Cℓ2 (g)  2PCℓ3 (ℓ) ΔH° = -636 kJ
PCℓ3 (ℓ) + Cℓ2 (g)  PCℓ5 (s) ΔH° = -138 kJ
1. Write a balanced chemical equation for the formation of one mole of PCℓ5 (s) from
its elements.
2. Calculate °fΔΗ for PCℓ5 (s).
H. (10 points) Using the data provided below answer the following questions.
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Specific heat for bromine 0.474 J/g⋅°C°vap ΔH for bromine 29.6 kJ/mol Boiling point
59.0 °C
1. Calculate the amount of heat involved in changing 15.0 g of liquid bromine, Br 2, at
room temperature (ℓ, 22.5 °C) to liquid bromine at 59.0°C (ℓ, 59.0°C).
2. Calculate ΔH involved in changing 15.0 g of liquid Br2 (ℓ, 59.0 °C) to vapor at
59.0°C.
(12 points) When ammonia reacts with dinitrogen oxide gas, liquid water and nitrogen
gas are formed. Values for Δ °f H are given below reactants and products. 2NH3 (g) +
3N2O (g) � 3H2O (ℓ) + 4N2 (g) Δ °f H (kJ/mol): -46.1 82.05 -285.5
1. What is the enthalpy change for the reaction?
2. What is the enthalpy change for a reaction that produces 0.0133 mol of nitrogen
gas?
3. Is heat evolved or absorbed?
A coffee-cup calorimeter contains 50.0 g of water at 60.51ºC. A 12.4 g piece of
graphite at 24.21ºC is placed in the calorimeter. The final temperature of the water
and the carbon is 59.02ºC. Calculate the specific heat of carbon. The specific heat of
water is 4.18 J/g·ºC.
A. 0.328 J/g·ºC
B. 0.639 J/g·ºC
C. 0.692 J/g·ºC
D. 0.721 J/g·ºC
E. 1.39 J/g·ºC
2. Determine the enthalpy of reaction for the decomposition of calcium carbonate
CaCO3(s) � CaO(s) + CO2(g) given the following thermochemical equations:
Ca(OH)2(s) � CaO(s) + H2O(l) ΔH = 65.2 kJ
Ca(OH)2(s) + CO2(g) � CaCO3(s) + H2O(l) ΔH = -113.2 kJ
C(s) + O2(g) � CO2(g) ΔH = -393.5 kJ
2Ca(s) + O2(g) � 2CaO(s) ΔH = -1270.2 kJ
A. 48.0 kJ
B. 178.4 kJ
C. 345.5 kJ
D. 441.0 kJ
E. 1711.7 kJ
3. Determine the enthalpy of formation of calcium carbonate from the
thermochemical equations given above in problem 2 (III.A.2)
A. -178.4 kJ
B. -493.2 kJ
C. -828.7 kJ
D. -980.6 kJ
E. -1207.0 kJ
4. All of the following statements are true EXCEPT
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A. the enthalpy change of an endothermic reaction is positive.
B. ΔH for a reaction is equal in magnitude but opposite in sign to ΔH for the reverse
reaction.
C. enthalpy is a state function.
D. enthalpy change is dependent upon the number of steps in a reaction
(10 points) Consider the following thermochemical equation for the formation of
diboron trioxide from pentaborane, B5H9(g), 2B5H9(g) + 12O2(g) � 5B2O3(s) + 9H2O(l)
ΔH = -9015.2 kJ
1. Given that ΔH°f for pentaborane is 62.76 kJ/mol, and ΔH°f for liquid water is
-285.8 kJ/mol, what is ΔH°f for B2O3?
2. Assuming 100% yield, how much heat is given off when 5.00 L of air (21%O 2 by
volume) at 756 mm Hg and 25.0 °C reacts with an excess of pentaborane? When 1.00
g of acetylene, C2H2, is burned, 48.2 kJ of heat is given off. When 0.750 g of
acetylene is burned in a bomb calorimeter (heat capacity = 1.117 kJ/°C), the final
temperature of the bomb calorimeter is 54.5°C. What is the initial temperature of the
calorimeter when reaction is complete?
In a coffee cup calorimeter, 50.0 mL of 0.100 M AgNO3 and 50.0 mL of
0.100 M HCl are mixed to yield the following reaction: Ag+(aq) + Cl-(aq) � AgCl(s)
The two solutions were initially at 22.60°C, and the final temperature is 23.40°C.
Assume that the specific heat of the solution is 4.07 J/g·°C and that the combined
solution is 100.0 g.
1. Calculate the heat that accompanies this reaction in kJ/mol of AgCl formed.
2. How many moles of AgCl are obtained from the reaction?
3. What is the enthalpy change per mole of AgCl?
1. Which substance has a heat of formation equal to zero at 25°C and
1 atm?
1. O3(g)
2. O3(s)
3. H+(aq)
A. 3 only
B. 1 and 3 only
C. 1, 2, and 3
D. 2 only
2. For the reaction
2Al2O3 (s) → 4Al (s) + 3O2 (g) ΔH° = 3351.4 kJ
Δ °f H for Al2O3 (s) in kJmol is ___
Given that
C(s) + 2H2(g) � CH4(g) ΔH = -74.6 kJ
C(s) + 2Cl2(g) � CCl4(g) ΔH = -95.7 kJ
H2(g) + Cl2(g) � 2HCl(g) ΔH = -92.3 kJ
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Name_________________________________________
Date______________
Period_________
calculate the enthalpy change for CH4(g) + 4Cl2(g) � CCl4(g) + 4HCl(g)
(12 points) Instant cold packs, often used to ice athletic injuries on the field, contain
ammonium nitrate and water separated by a thin plastic divider. When the divider is
broken, the ammonium nitrate dissolves according to the following endothermic
reaction:
NH4NO3(s) � NH4+(aq) + NO3-(aq)
1. Calculate the standard enthalpy change for the reaction using the following data:
° Δ f H (NH4NO3) = -365.6 kJ/mol; ° Δ f H (NH4+(aq)) = -132.5 kJ/mol;
° Δ f H (NO3-(aq)) = -205.0 kJ/mol
2. 1.25 g of NH4NO3 is dissolved in enough water to make 25.0 mL solution at 20.0ºC.
Calculate the temperature reached by the solution. Use 1.0 g/mL as the density of
the solution and 4.18 J/g°C as the specific heat capacity.
3. For the reaction the following reaction 2H2(g) + O2(g) � 2H2O(ℓ), the enthalpy
change is -285.8 kJ/mol. The enthalpy of formation of H2O(g) is _________ -285.8
kJ/mol.
4. A sample of iron (specific heat 0.450 J/g·°C) and a sample of water
(specific heat = 4.18 J/g·°C) with equal masses, each absorbs 200 J of
heat. ΔT for the iron is _________ ΔT for the water.
5. The heat capacity of a block of iron (specific heat 0.450 J/g·°C) weighing 2.50 kg is
_________ 8.47 X 102 J/°C.
1. For the process 2Bi(s) + 3Cℓ2(g) → 2BiCℓ3(s) ΔH° = -758.2 kJ Calculate ΔH° for the
reaction below:
BiCℓ3(s) → Bi(s) + 3/2C ℓ2(g)
A. +27.3 kJ B. -27.3 kJ C. +379.1 kJ D. 1516.4 kJ E. -379.1 kJ
2. Given the following equations and ΔΗ° values, determine the heat of reaction at 298
K for the reaction:
C2H2(g) → 2C(s) + H2(g) ΔH° =
C2H2(g) + 5/2O2(g) → 2CO2(g) + H2O (ℓ) ΔH° = -1299.5 kJ
H2(g) + 1/2O2(g) → H2O(ℓ) ΔH° = -285.8 kJ
C(s) + O2(g) → CO2(g) ΔH° = -393.5 kJ
A. -620.2 kJ B. +687.0 kJ C. -1978.8 kJ D. -226.7 kJ
3. Using the standard enthalpies of formation, calculate the standard enthalpy change
for the following reaction. Mg(OH)2(s) + 2NH4+(aq) → Mg2+(aq) + 2NH3(g) + 2H2O(ℓ)
A. 58.9 kJ B. -518.0 kJ C. -260.4 kJ
D. -435.0 kJ E. -258.3 kJ
C. (6 points) A 225.0 g sample of water at 25.0°C is added to 334.0 g of water at
15.0°C in a thermally insulated container. What will be the final temperature of water?
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Name_________________________________________
Date______________
Period_________
Standard enthalpy of formation (kJ/mol)
Mg(OH)2(s) -924.5
NH4+(aq) -132.5
Mg2+(aq) -466.8
NH3(g) -46.1
H2O(ℓ) -285.8
D. (10 points) Consider the following reaction for the combustion of phenol. A 1.800
grams sample of phenol, C6H5OH, (MM = 90.11 g/mol) was burned in excess oxygen
in a bomb calorimeter. The temperature of the calorimeter plus contents rose from
21.36°C to 26.37°C. The heat capacity of the calorimeter and contents was 11.66
kJ/°C. C6H5OH(ℓ) + 7O2(g) → 6CO2(g) + 3H2O(ℓ)
1. What is the value of q for the reaction mentioned above?
2. Is the reaction exothermic?(Yes or No)
3. What is the value of q for the reaction when 15.00 L of carbon dioxide at 25°C and
1.00 atm is formed?
D. (5 points) Consider the following thermochemical equation:
2PbO (s) → 2Pb(s) + O2(g) ΔHº = 438.0 kJ What is the heat of formation of PbO(s)?
E. (10 points) The following questions are related to the condensation of 138.21 g
sample of ethanol gas (C2H5OH), (MM = 46.07 g/mol) at 78.4°C to liquid ethanol at
25.0°C. (Specific heat of C2H5OH (ℓ) = 2.43 J/g⋅°C, enthalpy of vaporization = 38.6
kJ/mol and normal boiling point = 78.4°C)
1. What is the enthalpy change, ΔH, for 138.21 g of ethanol:
C2H5OH(g, 78.4°C) → C2H5OH(ℓ, 78..4°C)?
2. What is the enthalpy change, ΔH, for 138.21 g of ethanol:
C2H5OH(ℓ, 78.4°C) → C2H5OH(ℓ, 25.0°C)?
3. What is the overall enthalpy change in condensing 138.21 g of ethanol gas at
78.4°C to 25.00°C?
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Name_________________________________________
Date______________
Period_________
Ch 9
(10 points) A wet shirt with 95 g water on it is hung to dry in a small room at 25°C
where the partial pressure of water in the room's air is initially 0.020 atm. The vapor
pressure of water at 25°C is 0.032 atm. What is the minimum volume the room must
have to allow the shirt to completely dry?
The triple point of water occurs at 0.01°C and 0.0060 atm. Air containing
0.004 atm water vapor is cooled. What condensed phase(s) form(s).
A. Liquid B. Solid C. Both liquid and solid
To answer questions 2 and 3 use the following phase diagram for carbon dioxide. (not
to scale)
_____ 2. The critical point of CO2 occurs at 31°C and 73 atm. Gaseous CO2 at 35°C
is cooled until a condensed phase forms. What is the form of that condensed phase?
A. solid B. liquid
_____ 3. The critical point of CO2 occurs at 31°C and 73 atm. Gaseous CO2 at 25°C
is compressed until a condensed phase forms. What is the form of that condensed
phase?
A. solid B. liquid
_____ 4. HF has a higher boiling point, 19°C, than HCl, -85°C. What interaction is
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Name_________________________________________
Date______________
Period_________
the major factor for this difference?
A. dispersion forces B. dipoles forces C. hydrogen bonding
Water's ΔHvap = 40.7 kJ/mol. At the top of a very high mountain, water boils
at 77°C. What is atmospheric pressure at the mountaintop?
For the following question, use (LT for less than, GT for greater than, EQ
for equal to, MI for more information needed).
2. The vapor pressure of compound Q is 125 mmHg at 300K. Given a
sealed flask with some liquid Q present, the vapor pressure in the flask
is __ 125 mmHg.
B. (10 points) ΔHvap(H2O) = 40.7 kJ/mol. What is its vapor pressure at 50oC,
remembering
that its normal boiling point is 100oC?
C. (10 points) For cyclohexane, (MM = 84.1 g/mol) the vapor pressure at 25.5°C is
100.0 mm Hg. 0.0500 grams of cyclohexane are placed in a 50.00 mL flask at 25.5°C.
What is the mass of gaseous cyclohexane in the flask?
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