1.
2.
3.
4.
5.
(a) Solder is an alloy made of tin and lead that is
used in electronic circuits. A certain solder
has
a melting point of 224 oC. What is its
melting
point in oF? in K? 435 oF ; 497 K
(b) Mercury, the only metal that exists as a liquid
at room temperature, melts at – 38.9oC.
Convert its melting point to oF -38.02 oF
Suppose you are discontented with the existing
temperature scale and you decided to formulate a
new one in degrees Ang, oA and that on this scale,
water boils at 125 oA and freezes at 12.0OA.
a) Convert a temperature of 42.0OA to OC. 26.6
O
C
b) Convert a temperature of 24.0OF to OA. 6.98
O
A
A piece of silver (Ag) metal weighing 194.3 g is
placed in a graduated cylinder containing 242.0 mL
of water. The volume of the now reaches 260.5
mL. From these data, calculate the density of
silver. 10.50 g/mL
The following procedure was used to determine
the volume of a flask. The flask was weighed dry
and then filled with water. If the masses of the
empty flask and filled flask were 56.12 g and
87.39 g, respectively, and the density of water is
0.9976 g/cm3, calculate the volume of the flask in
cm3. 31.35 cm3
A cylindrical glass tube 12.7 cm in length is filled
with mercury. The mass of mercury needed to fill
the tube is 105.5 g. Calculate the inner diameter
of the tube in cm. Density of mercury is 13.6
g/mL. 0.882 cm
01. (a)
e.g4
Peroxyacylnitratev (PAN) is one of the
components of smog. It is a compound of
C, H, N and O. Determine its empirical
formula
from
the
following
percent
composition by mass: 19.8 % C, 2.50 % H,
11.6 % N. C2H3NO5
e.g
5
Monosodium glutamate (MSG), a food
flavor enhancer, has been blamed for
“Chinese
Restaurant
Syndrome,”
the
symptoms of which are headaches and
chest pains, MSG have the following
composition by mass: 35.51 % C, 4.77 %
H, 37.85 % O, 8.29 % N and 13.6 % Na.
What is the molecular formula if its
molar mass is 169 g? NaC5H8NO4
e.g6
When 0.1156 g of a compound, composed
of carbon, hydrogen and nitrogen is
reacted with oxygen, 0.1638 g CO2 and
0.1676 g H2O are collected. Determine
the E.F. of the compound. CH6O
e.g7
Terephthalic
acid
is
an
important
chemical used in the manufacture of
polyesters and plasticizers. It contains
only C,H and O. Combustion of 19.81 mg
of terephthalic acid produced 41.98 mg
CO2 and 6.45 mg H2O. The molar mass of
Complete the following table:
terephthalic acid is 166 g. Calculate the
SYMBOL
Z
A
PROTON
NEUTRON
ELECTRON
Sn
50
118
50
68
50
Ag
47
109
47
62
47
Ar
18
40
18
22
18
Cs
55
133
55
78
55
(b)
7.174, what is the natural abundance of the
lightest isotope? 79.6 %
E.F. and the M.F. of terephthalic acid.
EF: C4H3O2
MF : C8H6O4
e.g8
A 0.755 g sample of hydrated copper (II)
sulfate (CuSO4 xH2O) was heated carefully
until it is changed completely to anhydrous
Determine the number of subatomic
copper (II) sulfate, CUSO4, with a mass of
properties of the element mercury, Hg,
0.438 g. Determine the
given the symbol
200
value
of
x
(molecules of water). CuSO4 .6H2O
X ,
80
e.g9
P = 80 ; E = 80; N = 120
A sample of MgSO4 x H2O weighing 8.129 g is
heated until all the water of hydration is
02. The atomic weight of element X is 51.7 u. If
element X consists of 2 isotopes that have mass
driven off.
nos. of 50.0 and 52.0, what is the percent
compound, MgSO4,
abundance of the lighter isotope? 15.0 %
the formula of the hydrate? MgSO4 .7 H2O
03. Naturally occurring element Z, consists of Z-24
(mass is 23.99 u), Z-25 (mass is 24.99 u) and Z-26
(mass is 25.98 u). If the natural abundance of Z25 is 10.0% and the isotope ratio Z-24/Z-26 is
1.
The
resulting
anhydrous
weighs 3.967 g. What is
A compound of chlorophene (hexachlorophene),
used in making germicidal soaps, has the percent
composition by mass: 38.37 % C, 1.49 % H, 52,28
% Cl and 7.86 % O. What is the empirical formula
3NaHCO3(aq) + C6H8O7(aq)  3CO2(g) +
of this compound? C13H6Cl6O2
2.
3H2O(l) + Na3C6H8O7(aq)
A 0.1888 g sample of a hydrocarbon produces
0.6260 g CO2 and 0.1602 g H2O in a combustion
analysis. Its molecular mass is found to be 106 g.
For this hydrocarbon, determine its:
(a) mass percent composition90.0 % C ; 9.50 %
(a)
What mass of C6H8O7 should be used for
every 1.00 x 102 mg of NaHCO3? 79.2 mg
(b) What mass of CO2(g) would be produced
from such mixture? 78.6 mg
e.g How many grams of N2F4 can theoretically be
prepared from 4.00 g of NH3 and 14.0 g of F2.
H
The chemical equation for the reaction is:
(b) E.F. C4H5
NH3 + F2  N2F4 + HF 7.66 g
(c) M.F. C8H10
3.
A
certain
hydrate
is
found
to
have
the
e.g.
H2S + NaOH  Na2S + H2O
composition 20.3% Cu, 8.95% Si, 36.3% F and
34.5% H2O, by mass.
How many grams of Na2S are formed if 2.05 g of
What is the empirical
H2S is bubbled into a solution containing 1.84 g of
formula of the hydrate? CuSiF6 .6H2O
4.
NaOH, assuming that the limiting reactant is
Determine the empirical formula of benzyprene, a
completely consumed? 1.80 g
suspected cancer-causing agent found in cigarette
smoke and smoke produced in charcoal grilling of
meat, which consists of 95.21% C and 4.79% H by
e.g
by controlled reaction between cyclohexane,
Selenium, an element used in the manufacture of
C6H12 and O:
photoelectric cells and solar energy devices,
C6H12 + O2  H2C6H8O4 + H2O
forms two oxides. One has 28.8% O by mass and
the other 7.8% O.
these oxides?
Adipic acid, H2C6H8O4, is a raw material used in
the production of nylon. It is made commercially
mass. C5H3
5.
Consider the following reaction:
(a)
What are the formulas of
starting with 25.0 g of cyclohexane and that
Propose acceptable names for
cyclohexane is the limiting reactant, what is
these oxides. SeO2 – selenium dioxide
the theoretical yield of adipic acid? 43.5 g
SeO3 - selenium trioxide
6.
(b) If you obtain 33.5 g of adipic acid from the
Para-cresol is used as a disinfectant and in the
reaction, what is the percent yield of adipic
manufacture of herbicides and artificial food
flavors.
A 0.4039 g sample of these carbon-
hydrogen-oxygen compound yields 1.1518 g CO2
acid? 77.0 %
e.g.
be
the E.F. of para-cresol? C7H8O
What is the E.F. of this
substance?
C8H8O2 or C6H5CO2CH3
e.g The reusable rockets of the U.S. space shuttle
use a mixture of aluminum and ammonium per
chlorate for fuel.
reaction is:
AlCl3(s) + 3NO(g) + 6H2O(g)
What mass of NH4ClO4 should be used in the fuel
mixture for every 1.00 kg of Al? 4.35 kg
e.g. Elixirs, such as Alka-Seltzer, use the reaction of
sodium bicarbonate with citric acid in aqueous
solution to produce a fizz:
an
important
prepared
by
the
reaction
between
hydroxide:
2C6H5NO2 + 4C6H14O4
 C12H10N2 + 4C6H12O4 +
4H2O
(a)
What is the theoretical yield of azobenzene
when 115 g of nitrobenzene and 327 g of
triethylenglycol are allowed to react? 85.1 g
(b)
If the reaction yields 55.0 g of azobenzene,
what is the percent yield of azobenzene? 64.6 %
A possible equation for the
3Al(s) + 3NH4ClO4(s)  Al2O3(s) +
is
C6H14O4, in the presence of zinc and potassium
used in the manufacture of perfumes, is found to
1.252 g oxygen.
C12H10N2,
nitrobenzene, C6H5NO2 and triethylene glycol,
A 5.323 g sample of methyl benzoate, a compound
contain 3.758 g carbon, 0.316 g hydrogen and
Azobenzene,
intermediate in the manufacture of dyes. It can
and 0.2694 g H2O in combustion analysis. What is
7.
Assuming that you carry out this reaction
e.g.
The reaction of 13.0 g of C4H9OH, 21.6 g NaBr
and 33.8 g of H2SO4 yields 16.8 g of C4H9Br in
the reaction:
C4H9OH + NaBr + H2SO4  C4H9Br +
NaHSO4 + H2O
What are the:
(a) theoretical yield 24.0 g
(b) actual yield 16.8 g
(c) per cent yield of the reaction? 70.0 %
2.
Many
antacids
contain
aluminum
hydroxide,
C2H6(g), if all gases are measured at the same
Al(OH)3, as their active ingredient.
temperature and pressure? 52.5 L
(a) Write a balanced equation for the reaction of
2C2H6(g) + 7O2(g)  4CO2(g) +
HCl in stomach acid with solid Al(OH)3 to
What volume of CO2 is produced? 30.0 L
form water and aqueous AlCl3.
e.g
14
What volume of phosphine, PH3 (measured at
(b) How many grams of HCl reacts with 2.50 g of
STP) would be formed by the reaction of 54.6
Al(OH)3? 3.51 g
3.
6H2O(g)
g of calcium phosphide with water? 13.0 L
Ethylene, C2H4, burns in air:
Ca3P2(s) + 6H2O(l)  3Ca(OH)2(s) +
2PH3(g)
C2H4 + O2  CO2 + H2O
How many grams of CO2 can form when a mixture
of 2.93 g of C2H4 and 5.29 g of O2 is ignited,
assuming only the reaction above occurs? 4.85 g
4.
helium gas has a total pressure of 0.900 atm.
amounts of O2 involves the decomposition of
What is the partial pressure of oxygen? 0.100
How many grams of O2 can be prepared
from 4.50 g of KClO3? 1.76 g
atm
e.g
Consider the reaction:
Al + Cl2  AlCl3
volume will this sample occupy dry at STP? 32.9
allowed to react.
mL
e.g
(a) What is the limiting reactant? Al
What is the partial pressure of each gas in a
mixture which contains 10 mols of He, 2.0 mols
(b) How many moles of AlCl 3 are formed?
1.50
of N2 and 0.50 mol of O2 if the total pressure of
mol
the mixture is 5.0 atm? PHe = 4.0 atm
A strip of Zn metal weighing 2.00 grams is placed
PN2 = 0.80 atm
in an aqueous solution containing 2.50 g of silver
PO2 = 0.20 atm
nitrate, causing the following reaction to occur:
1.
What is the density of fluorine gas at STP? 0.848
2.
A gas has a density of 0.992 g/L at 91.0 o and 750
Zn + AgNO3  Ag + Zn(NO3)2
How many grams of Ag will form? 1.58 g
7.
370 ml of oxygen is collected over water at 23.0o
and a barometric pressure of 0.992 atm. What
A mixture of 1.50 mol of Al and 3.00 mol of Cl 2 is
6.
A mixture of 40.0 g of oxygen and 40.0 g of
A common laboratory method for preparing small
KClO3.
5.
e.g
g/L
Automotive airbags inflate when sodium azide,
torr. What is the molecular weight of the gas?
NaN3, rapidly decomposes to the elements.
30.02 g/mol
(a) Write a balanced equation for this reaction?
3.
(b) How many grams of NaN3 are required to form
A certain gas occupies a volume of 100 ml at a
temperature of 29.0oC. What will be its volume at
1.00 g N2? 1.62 g
10.0oC if the pressure remains constant? 93.7 mL
(c) How many grams of NaN3 are required to
4.
750 ml of a gas at 300 torr pressure and 50.0 oC is
produce 12.0 ft3 of N2 if the gas has a density
heated until the volume of the gas is 2000 ml at a
of 1.25 g/L? 1.32 x 103 g
pressure of 700 torr.
What is the final
temperature of the gas? 1737 oC
e.g
The ratio of the rate of effusion of gas X to
5.
the rate of effusion of N2(g) is rx
L steel cylinder if the pressure is 10.0 atm and
rN2
What is the molecular weight of gas X if it
e.g
the temperature is 27.0oC? 20.3 mols
6.
66.0 g of He gas are pumped into a 0.500 L
effuses 0.876 times as rapidly as N2? 36.4
cylinder at 60.0oC. What is the pressure of the
g/mol
gas in the cylinder?
The diffusion rate of an unknown gas is
7.
Suppose 100 ml of oxygen is collected over water
measured and found to be 31.50 ml/min.
in the laboratory at a pressure if 700 torr and a
Under identical experimental conditions the
temperature of 20.0oC, what would the volume of
diffusion rate of O2 is found to be 30.50
dry oxygen be at STP? 83.66 mL
ml/min. which of the following is the unknown
8.
gas? CH4, CO, NO, CO2 or NO2? MW = 30.0
What volume of oxygen is required for the
complete combustion of 15.0 L of ethane,
Calculate the volume of oxygen necessary to burn
50.0 L of CO. 25.0 L
g/mol, gas is NO
e.g
How many mols of hydrogen are present in a 50.0
2CO + O2  2CO2
9.
A container is filled with gas to a pressure of 5.00
atm at 30.0oC.
a) What pressure will develop inside the sealed
container when it is warmed to 100oC?
08. A commercial bleaching solution contains 3.62
6.16
mass percent sodium hypochlorite, NaOCl. What
atm
is the mass of NaOCl in a bottle containing 2500.
b) At what temperature would the pressure be
100 atm? 5.79 x 10
3 o
g of bleaching solution? What
C
be
its
concentration expressed as mole fraction NaOCl?
10. What volume will 10.0 g of CO occupy at STP?
Assume CO us an ideal gas. 8.00 L
11.
will
XNaOCl = 0.00903
09. What is the mole fraction of naphthalene, C10H8 in
o
A 500 ml sample of gas weighs 0.326 g at 100 C
a solution made by dissolving 36.5 g naphthalene in
and 380 torr.
420 g toluene, C7H8? 0.0588
What is the molecular weight of
the gas? 39.9 g/mol
10. A solution containing 46.0 g acetone, C3H6O, and
12. Find the density of ammonia, NH3, at 100oC when
66.0 g of H2O, has a density of 0.926 g/ml.
confined by a pressure of 1600 mm Hg. 1.17 g/L
Calculate: (a) the mass percentage 69.7 %
13. The time required for a given volume of N2 to
(b) the mole fraction Xacetone = 0.178
effuse through an orifice is 35.0 sec. Calculate
Xwater = 0.822
the MW of the gas which requires 50.0 sec to
(c) the molality 12.0 m
effuse through the same orifice under the same
(d) the molarity of the solution 6.55 M
conditions. 57.1 g/mol
14. A cylinder contains 36.0 g He gas, 140.0 g of N2
gas and 264.0 g of CO2.
e.g.1
A lamp draws a current of 3.00 amperes. Find
the charge in coulombs used by the lamp in 60.0
a) What is the mole fraction of He? 0.450
secs. 180 coulombs
b) The total pressure of the cylinder is given at
15.0 atm. Compute for the partial pressure if
e.g.2
the He gas in the atmosphere. 6.75 atm
A dynamo delivers 25.0 amperes at 220 volts.
(a) Determine the power in kilowatts supplied
by
01. A solution is prepared by dissolving 25.0 ml
the dynamo.
(b)
How much electrical energy in kilowatt-
ethanol, C2H5OH (d = 0.789 g/ml), in enough water
hour,
to produce 250.0 ml solution.
hours?
What is the
molarity of ethanol in the solution? 1.71 M
5.50 kW
is supplied by the dynamo in 3.50
19.3 kW-hr
(c) What is the cost of energy at P 7.9207
02. A 22.3 g sample of acetone, (CH3)2CO, is dissolved
per kilowatt-hour? Php 152.47
in enough water to produce 125 ml solution. What
is the molarity of acetone in this solution? 3.08 m
e.g1
What weights of gold and chlorine will be
03. How would you prepare 425 g of an aqueous
formed when 10,000 coulombs of electricity is
solution containing 2.40 % by mass of sodium
passed through a water solution of gold (III)
acetate, NaC2H3O2? Dissolve 10.2 g NaC2H3O2 in
chloride? The electrode reactions are:
414 g H2O
04. A
particular
analytical
chemistry
Au3+ + 3e-  Au 6.80 g
procedure
requires 0.0500 M K2CrO4. What volume of 0.250
M K2CrO4 must we dilute with water to prepare
0.100 L of 0.0500 M K2CrO4? 0.0200 L
05. Lauryl
alcohol,
C12H25OH,
is
prepared
2Cl-  Cl2 + 2ee.g2
2.50 amp. How many grams of Cu plate out in
30.0 min? 1.48 g
from
coconut oil; it is used to make sodium lauryl
sulfate, a synthetic detergent.
What is the
molality of lauryl alcohol in a solution containing
e.g3
06. What mass of iodine, I2, in grams, must be
dissolved in 315.0 ml of carbon disulfide, CS 2 (d =
1.261 g/ml), to produce a 0.182 m solution? 18.3
g
07. An aqueous solution is 36.0 % HNO3 by mass and
has a density of 1.2205 g/ml.
What is the
molarity and molality of this solution? 6.97 M ;
8.93 m
How many minutes will it take to plate out 58.7
g of Ni from a solution of NiSO4, using a
current of 0.900 amp? 3.57 x 104 min
15.6 g of lauryl alcohol dissolved in 125 g of ethyl
alcohol, C2H5OH? 0.671 mol/kg
A Cu2+ solution is electrolyzed using a current of
e.g4
If 0.690 g of Ag is deposited on the cathode of
a silver coulometer
(a)
the
How many coulombs have passed through
circuit? 617 coulombs
(b) If the process takes 20 minutes, what was
the rate of the current? 0.514 A
e.g5
e.g6
How many grams of Ca metal could be produced
(a) the expression for the approximate amount
by the electrolysis of molten CaBr2 using a
of the radioactive material present at any
current of 30.0 amp for 10.0 hours? 224 g
time t. N = No e-0.0527t/yr
(b) the mass of the material after 5 years. 38.4
How many seconds will be required to produce
mg
1.0 g silver metal by the electrolysis of a AgNO 3
(c) the time at which the material decayed to
solution using a current of 30 amperes? 29.8
sec
e.g
7
one half of its initial mass 13.2 years
3. Carbon-14 is one of the isotopes of carbon, with a
half-life of 5,730 years. Find the decay constant
for this element. 1.209 x 10-4 / year
What is the equivalent weight of the metal if
the current of 0.300 amp will cause 0.129 g of
the metal to plate out of a solution undergoing
electrolysis in 40.0 minutes? 17.3 g
4. The half-life of hafnium-156 is 0.0250 s. How long
will it take a 560. g sample to decay to one-fourth
its original mass? 0.0500 s
1.
A certain radioactive material weighing 500. g is
found to be 420. g after 30.0 days.
How long
would it take the substance to be 100. g?
277
days
2. Radium decomposes at a rate proportional to the
quantity of radium present.
Suppose that it is
found that in 25.0 years approximately 1.10 % of a
certain
quantity
of
radium
has
decomposed.
Determine approximately how long will it take for ½
the original amount of radium to decompose. 1.57
x 10 3 years
3. A certain radioactive substance has a half-life of
38.0 hours. Find how long it takes for 90.0 % of
the radioactivity to be dissipated. 127 hours
4. The half-life of a material is 7.50 years.
How
much of a 3.00 mg sample will be left after a 20.0year period? 0.473 mg
5. Carbon-11, used in medical imaging has a half-life
of 20.4 minutes.
formed
and
then
The carbon-11 nuclides are
incorporated
into
desired
compounds. The resulting sample is injected into a
patient and the medical image is obtained.
The
entire process takes five half- lives. What percent
of the original carbon-11 remains at this time?
3.12 %
1.
Starting with 50 grams of strontium-90, 40.45
grams remain after a five-year period.
(a) What is the half-life of strontium? 16.3 years
(b) How much strontium-90 will remain after
12 years? 30 g
2. A certain radioactive material is known to decay at
a rate proportional to the amount present.
If
initially there are 50 mg of the material and after
2 hours it is observed that the material has lost 10
% of its original mass, find,
5.
Gold-198 has a half-life of 2.70 days. How much
of a 96.0 g sample of gold-198 will be left after
8.10 days? 12.0 g