5.
EXERCISES
CHAPTER 2 and 3 : ATOM THEORY &
ELECTRONS IN ATOMS
1. How many electrons of Kr atom have the magnetic
quantum number ml = +1
Answer: 8
2. How many electrons of Kr atom do have the
angular momentum quantum number l= +1 ?
Answer: 18
3. Write the electron configuration of Sn( Z=50) and
Ca2+ (Z=20) and Cl1- (Z=17)
4. Copper (Cu) has two isotopes: The isotope
Cu(Z=29 ; A=63) has the atomic mass of 62,9298
amu. The other isotope has the atomic mass of
64,9278 amu. What are the natural percent
abundances of these two isotopes, if the atomic
mass of Copper(Z=29) is 63,546 amu?
There are three naturally occuring isotopes of magnesium:
25
26
24
12𝑀𝑔 𝑤𝑖𝑡ℎ 𝑎 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 𝑛𝑎𝑡𝑢𝑟𝑎𝑙 𝑎𝑏𝑢𝑛𝑑𝑎𝑛𝑐𝑒 𝑜𝑓 78,99% ; 12𝑀𝑔 𝑎𝑛𝑑 12𝑀𝑔
.
25
The 24
12𝑀𝑔 isotope weighs 23,985042 u. The mass of 12𝑀𝑔 is
24,985837 u and the mass of 26
12𝑀𝑔 isotope is 25,982593 u. The
weighted average atomic mass of magnesium is 24,30505187 u.
Determine the percent natural abundances of the other two
26
25
26
isotopes 25
12𝑀𝑔 𝑎𝑛𝑑 12𝑀𝑔 ( 12𝑀𝑔 = 10% ; 12𝑀𝑔 = 11,01%))
6. Complete the table given below
Element Z
Sn
50
Ag
I
53
Ar
W
Cs+
Cu2+
A
120
109
127
184
Proton
Neutron Electron
53
22
110
78
34
6.Calculate the O.S of the elements underlined in the
given compound
a) H3PO4
f)B2Cl4
k) Ca2VO4
b) Cr2O72g) XeO64l) W2Cl93c) FeO42h) NO2+
m) NH2OH
d) SF6
i) N2H4
n) UO2+
e) TiO2
j) CaN2O2
o) U2Cl10
7. a)Write the electron configurations in condensed
form of the following ions and determine the
number of the unpaired electrons for the given ions
+
2+
2+
2+
12Mg2
24Cr
27Co
46Pd
+
47Ag
53I
2+
3+
22Ti
26Fe
56Ba
14Si
34Se
b) Which of them are diamagnetic, which of them
are paramagnetic?
CHAPTER 3:QUANTUM NUMBERS
1. Given the spdf notation of the element Z as follows:
1 s2 2 s2 2 p6 3 s2 3 p6 4 s1 3 d10
The total number of electrons having magnetic quantum
number ml > +1
a) 4
b)2
c) 6
d)1
e)10
The total number of electrons having magnetic quantum
number ml = 0
a) 11
b)15
c)29
d) 7
e) 13
The total number of electrons having angular momentum
quantum number l = 3
a) 0
b) 10
c) 1
d)6
e)12
The total number of electrons having angular momentum
quantum number l = 2
a) 1
b) 6
c)10
d)12
e)0
The total number of electrons having principal quantum
number n>2
a) 29
b)10
c)19
d) 1
e)16
2.The element Z has the electron configuration of : 1 s2
2s22p6 3s23p6 4s23d10 4p6 5s2 4d10 5p6 4f7 5d1 6s2
How many electrons do have the principal quantum
number n>4
a) 38
b)30
c)11
d)9
e)8
How many electrons do have the angular
momentum quantum number l=3
a)0
b)36
c)21
d)7
e)28
How many electrons may have the magnetic
quantum number │ml│=3
a) 2
b)4
c)7
d) 18
e)24
CHAPTER 4: THE PERIODIC TABLE
1.Which of the atom pairs written below you would
expect to be larger? Explain your reasoning?
a) As and Br
b) As and Bi c)As and Sn d)Ga and
As e) Ca and Ga f )Cs and Rb
2. Which of the atom pairs you would expect to have
higher first ionization energy? Explain your conclusion?
a) S and Ar b)Ar and Kr c)S and As d)Ba and Sr
e)Cs and Ba f)Cl and I
g) I and Xe h)Se and Cl
3. Which of the elements from the 3. Period(from Na to
Ar)
a) has the greatest atomic radius
b) has the highest first ionization energy
c) has the most metallic character
d) has the most non-metallic character
e) is inert (inactive in reactions)
4. Given the ions:
O2-, Ne, Na+, F-, Mg2+, Al3+
a) Arrange the ions in the increasing order of atomic
radius
b) Which of them is a noble gas?
c) Which of them has the highest negative electron
affinity?
d) Which of them has positive electron affinity?
e) Which of them has the lowest first ionization
energy?
5. The ion X3+ has the electron configuration: 1 s2 2 s2 2
p6 3 s2 3 p6 4 s2 3 d10 4 p6
According to this information which of the statements
can be true? (For each question just one right answer is
possible)
The element X is a
a) Metal
b) Non-metal
c) Metalloid
The element is in the gruop
a) IA
b) IIB
c) III B
d) 4A
e) 8A
It forms with Chlorine(Cl) the following compound
a) XCl5
b) X2Cl3
c) X3Cl2
d) XCl3
e) XCl2
Its proton number is
a) 36
b) 20
c) 28
d) 39
e) 33
Its neutron number is
a) 48
b) 41
c) 50
d) 89
e) 84
It(the element itsself) is
a) Diamagnetic
b) Paramagnetic
c) Ferromagnetic
5. The ion X2- has the electron configuration: 1 s2 2 s2 2 p6
3 s2 3 p6 4 s2 3 d10 4 p6 5s2 4d10 5 p6
According to this information which of the statements
can be true? (For each question just one right answer is
possible)
The element X is a
a)Metal
b)Non-metal
c)Metalloid
The element is in the gruop
a)II A
b)IV B
c)VI A
d)VI B
e) VIIIA
It has the oxidation state(O.S) in the compound XF6
a) +6
b) -2
c) +4
d) -4
e) +1
Which of the statements is correct?
a) The element makes ionic bonds with halogenes
b) It is a transition element
c) Its ionization energy is greater than Iodine
d) The atomic radius of the element is greater than that
of its ion X2e) The element X is paramagnetic
7. Given the electron configuration of the ion X7+ : 1
s2 2 s2 2p6 3 s2 3p6
The element X is found in the group
a) IIA
b) IIIB
c) VIII A
d) VIB
e) VII B
What is the oxidation state of the element X in the
compound XO2
a) -3
b) +4
c) +2
d) -1
e) +7
Which of the statements described below is false?
a) The element X has a first ionization energy
lower than that of Kr
b) The element X has 5 electrons in its d orbitals.
c) The element X is paramagnetic, but its ion X7+ is
diamagnetic
d) Its oxides have acidic character
e) Its atomic radius is smaller than that of K
CHAPTER 5: CHEMICAL COMPOUNDS
8. Write the chemical formula of the following
compounds
a) Sulphurhexafluoride
b) Hypochlorousacid
c) Nickel(II)sulfate
d) Mercury(I)fluoride
e) Copper(II)chromate
f) Ammonimdichromate
g) Talium(I)hydroxide
h) Dichlorheptoxide
i) Lithiumnitride
j) Gold(III)oxide
k) Cobalt(II)nitrite
l) Iron(II)oxide
m) Dinitrogentetroxide
9. Name the compounds whose chemical formula are
given below
a)BrF3
b)Fe2(SO4)3
c)Cr2O3
d)TeF6
e)Au2S2
f) CaCO3
g)PbCrO4
h)InN
i) BaBr2
j) CCl4
m)NO
n) P2O5
o) CuCN
10. What is the weight percentage of the element
Be in the compound Be3Al2(SiO3)6 ?
(Be=9 ; Al=27 ; Si=28 ; O=16)
11. Ascorbic acid has the molecular weight of
176,14 g/mol and it contains 40,91% C ; 4,59% H
and 54,5% O by mass. What is the molecular
formula of ascorbic acid? (C=12,01 ; H=1,01 ;
O=16)
Answer: C6H8O6
12. Barbituric acid contains 37,5% C ; 3,15% H,
21,87% N and 37,47% O by mass. Determine the
empirical formula of barbituric acid (C=12,01 ;
H=1,01 ; N=14 ; O=16)
13. Cholesterol has the molecular weight of 386
g/mol and it contains 83,9% C ; 11,9% H and 4,1%
O by mass. What is the molecular formula of
cholesterol? (C=12,01 ; H=1,01 ; O=16)
14. Calculate the mole content and the total
number of atoms of the following molecules which
have a mass of 50 g. (F=19 ; H=1 ; O=16 ; C=12 ;
Cl=35,5)
a) F2
b) H2O
c) CCl4
15. If a hydrocarbon mixture is burnt with oxygen,
5,28 g of CO2 and 2,7 g of H2O are produced (C=12
; O=16 ; H=1)
a) Write the chemical reaction
b) Determine the empirical formula of the mixture
c) What is the mass of the sample burnt?
16. A compound consisting of C, H and N
elements was combusted with oxygen. In the end,
10,56 g of CO2 ; 2,52 g of H2O and 0,56 g of N2
were produced.
a) What is the empirical formula of the compound?
b) What is the mass of the compound burnt?
c) What is the efficiency of the oxygen, if there is
32 g. of O2 present in the container at the
beginning?
(C=12 ; H=1 ; O=16 ; N=14)
17.For the compound Ge[S(CH2)4CH3]4 , determine
a) the total number of atoms in one formula unit
b) the ratio, by number of C atoms to H atoms
c) the ratio, by mass, of Ge to S
d) the number of g S in 1 mole of the compound
e) the number of C atoms in 33,1 g of the compound
CHAPTER 6 and 7: GASES &
THERMOCHEMISTRY
18. A gaseous sample occupies 750 mL in a closed
vessel at 75˚C and 0,75 atm pressure. At which
temperature(˚C) does the sample have a volume of
1 L at 1 atm pressure?
19. A gaseous sample occupies 400 mL of volume
under standard conditions. What is the volume of
this gas at 77˚C and 2,5 atm?
20. A container is filled with a gas at 20˚C and 5
atm
a) If the container is heated up to 200˚C, how much
does the pressure increase?
b) At which temperature does the pressure reach 1
atm?
c) What will be the pressure at - 100˚C ?
21. What is the pressure in atm exerted on to a
vessel of 1 L in which 3,5 mole of a gas at 27˚C is
present.
22. Calculate the mole content of a gas in a vessel
of 5 L at 25˚C and 1 atm pressure
23. Calculate the density of C2H6 in g/L at 25˚C
and 1,25 atm (C=12 ; H=1)
24. The density of a gaseous substance is 0,362 g/L
at 150˚C and 0,455 atm pressure. Calculate the
molecular weight of this gas
25. The barometric pressure of an O2 sample with a
volume of 370 mL over water at 23˚C is measured
0,992 atm. What is the volume occupied by the
same sample under standard and dry conditions?
(Vapor pressure of O2 at 23˚C= 0,028 atm)
26. The following reaction is given:
3 Fe (s) + 4 H2O (g)
Fe3O4(s) + 4 H2
(g)
How many grams of iron(Fe) are required to form
100 L of H2 under standard conditions? (Fe= 55,8
g/mol)
27. The total pressure of a gaseous mixture
composed of 40 g O2 and 40 g He is 0,9 atm. What
is the partial pressure of O2? (O=16 ; He=4)
28. A gas mixture is composed of N2 and C2H6.
The partial pressure of N2 is 0,3 atm and the partial
pressure of C2H6 is 0,45 atm.
a)Calculate the mol fraction of each gas(BOTH N2
and C2H6 !!!)
b) What is the total mole content of the mixture, if
it occupies a volume of 20,4 L at 100˚C
c) Calculate the mass of each gas(N2 and C2H6)
28. The rate of effusion of N2 gas is 9,5 mL/s and its
density is measured 0,572 g/L.
a) Calculate the density of an unknown gas whose rate
of effusion was determined as 6,28 mL/s at 25˚C
and 0,5 atm (under the same conditions as in the
situation of N2)
b)What is the molecular weight of this gas?
29. 2,5 g sucrose (C12H22O11) is burnt with excess of
O2 in the presence of a calorimeter having a heat
capacity of 4,98 kJ/˚C and containing 1 kg water.
During the combustion the temperature of the
calorimeter and inside rises from 18,22˚C to
22,73˚C. How much heat in kJ/mol is evolved as a
result of the burning process? (C=12 ; H=1 ; O=16 ;
cwater= 4,18 J/g˚C)
30. 12,45 g of the sample P4O10 and 950 g of water are
placed into the reaction vessel of a calorimeter. The
temperature of the calorimeter rises from 22,815˚C
to 26,885˚C. The heat capacity of the calorimeter is
0,6904 kJ/˚C. Using this information, calculate the
enthalpy change of the reaction given below
(P=31 ; O=16) cwater= 4,18 J/g˚C
P4O10 (s) + 6 H2O (l)
4 H3PO4 (l)
31. Given that ΔHf (CO2) (g) = -393,5 kJ and ΔHf
*(H2O) (l) = -285,9 kJ and the reaction
CH4(g) + 2 O2(g)
CO2 (g) + 2 H2O (l)
ΔH˚= -890,4 kJ
Determine the standard enthalpy of formation of CH4
32. Given that ΔHf (CO2) (g) = -393,5 kJ and ΔHf
(Fe2O3) (s) = -822 kJ ; ΔHf (CO) (g) = -110,5 kJ
and the reaction
Fe2O3(s) + 3 CO(g)
2 Fe (s) + 3 CO2(g)
ΔH˚= ?
Determine the enthalpy change of the reaction
33. Determine the enthalpy change of reaction
CS2 (s) + 2 H2O (l)
CO2 (g) + 2 H2S (g)
By using the data below
I.
H2S (g) + 3/2 O2 (g)
(g) ΔH˚= - 562,6 kJ
II. CS2 (l) + 3 O2(g)
(g) ΔH˚= - 1075,2 kJ
H2O (l) + SO2
CO2 (g) + 2 SO2
34. Determine the enthalpy change of reaction
N2 (g) + ½ O2 (g)
N2O (g)
By using the data below
I. 2 NH3 (g) + 3 N2O (g)
3 H2O (l) ΔH˚= - 1010 kJ
II. 4 NH3 (g) + 3 O2 (g)
H2O (l) ΔH˚= - 1531 kJ
4 N2 (g) +
2 N2 (g) + 6
35. Determine the enthalpy change of reaction
B2H6 (g) + 6 Cl2 (g)
(g)
I.
BCl3 (g) + 3 H2O (l)
HCl (g) ΔH˚= - 112,5 kJ
II. B2H6 (g) + 6 H2O (l)
H2 (g) ΔH˚= - 493,4 kJ
III. ½ H2 (g) + ½ Cl2 (g)
ΔH˚= - 92,3 Kj
2 BCl3 (g) + 6 HCl
H3BO3 (s) + 3
2 H3BO3 (s) + 6
HCl
36. For each of the following reactions, indicate whether
ΔS for the reaction is positive or negative. If it is
not possible to determine the sign of ΔS from the
information given, indicate why?
a) Na2SO4 (s) + 4 C(s)
Na2S (s) + 4 CO(g)
b) 2 Hg (l) + O2 (g)
2 HgO (s)
c) 2 H2O (g)
2 H2 (g) + O2 (g)
d) Fe2O3 (s) + 3 H2 (g)
2 Fe (s) + 3 H2O (g)
e) Ni (s) + 4 CO(g)
Ni(CO)4 (l)
37. For the following reactions, indicate whether the
forward reaction tends to be spontaneous at low
temperatures, high temperatures or whether it
tends to be spontaneous at all temperatures. If the
information given is not sufficient to allow a
prediction, state why this is so:
a) PCl3 (g) + Cl2(g)
PCl5 (g) ΔH= - 87,9 kJ
b) CO2 (g) + H2 (g)
CO(g) + H2O(g) ΔH= +
41,2 kJ
c) NH4CO2NH2 (s)
2 NH3 (g) + CO2(g) ΔH= +
159,2 kJ
d) H2O(g) + ½ O2(g)
H2O2(g) ΔH= + 105,7 kJ
e) C6H6(l) + 15/2 O2(g)
6 CO2 (g) + 3 H2O (g)
ΔH= - 313,5 kJ
38. For the reaction given below, calculate ΔS and ΔG
at 25˚C, when the absolute entropy S˚of NH4Cl
(g) is 94,56 J/molK
NH3(g) + HCl(g)
NH4Cl (g) ; ΔH= - 176,9 kJ :
SNH3=192,3 J/molK ; SHCl= 186,8 J/molK
CHAPTER 8 : SOLUTIONS
39. The density of a concentrated as w/w(mass
percentage) 47% HI solution is 1,5 g/mL.
a)What mass of a concentrated solution should be used
in order to prepare 500 mL 0,6 M HI?
b) In order to prepare this concentrated solution (HI) , to
which volume (V) should it be fixed?
(H=
1 ; I=127)
40. Heptane and octane are together building up an
ideal solution. What will be the vapor pressure of
this solution at 40˚C , if it contains 3 mol of
heptane and 5 mol of octane? (P˚heptane =0,121 atm
at 40˚ C ; P˚octane = 0,041 atm)
41. Determine the vapor pressure of a substance in a 1
m aqueous solution at 50˚C which is not volatile
and does not dissociate in water. (P˚water = 0,122
atm at 50˚C)
42.A certain substance unvolatile and not dissociable in
water with a mass of 10,6 g and water of 90 g are
together forming a solution which has a vapor pressure
of 0,1867 atm at 60˚C . Calculate the molecular weight
of the solute using the Rault’s law. (P˚water = 0,1966 atm
at 60˚C)
43. Coniferin is a glycoside ( a derivative of sugar)
found in conifers (e.g fir trees). When a 1,205 g sample
of coniferin is subjected to combustion analysis, the
products are 0,698 g H2O and 2,479 g CO2 . A 2,216 g
sample is dissolved in 48,68 g H2O and the boiling point
of this solution is found to be 100,068˚C. (KBP for water
= 0,512 ˚C m-1)
a) Calculate the molecular weight of coniferin?
b) Find the molecular formula of coniferin(CxHyOz)
44. The molecular mass of hemoglobin is 6,86 x 104
amu. What mass of hemoglobin must be present per 100
mL of a solution to exert an osmotic pressure of 6,15
mm Hg at 25˚C?
45.The solubility of H2S (g) is 258 mL at STP per 100 g
H2O at 20˚C. A particular mineral water containing 0,15
% H2S by mass is kept at 20˚C under an atmosphere in
which the partial pressure of H2S is 255 mm Hg. How
much of H2S will be more dissolved or lost?
46. A 10% by mass solution of ethanol, C2H5OH in
water has a density of 0,9831 g/mL at 15˚C and 0,9804
g/mL at 25˚C. What is the molarity of C2H5OH in this
solution at each temperature?
47. Use your knowledge of strong, weak and
nonelectrolytes to arrange the following 0,01 m aqueous
solutions in the probable order of decreasing freezing
point:
C2H5OH , NaCl, MgBr2, CH3COOH, and Al2(SO4)3
CHAPTER 9- CHEMICAL KINETICS
1. The reaction
A+B
C + D is second order in A and
zero order in B. The value of rate of constant(k) is
0,0018 M-1min-1. What is the rate of this reaction
when [A] = 0,155 M and [B] = 4,68 M
2. The following data are obtained for the initial rates
of reaction in the reaction:
A+2B+C
2D+E
Experiment
1
2
3
4
5
[A], M
1,4
0,7
0,7
1,4
0,7
[B], M
1,4
1,4
0,7
1,4
0,7
[C] ,M
1
1
1
0,5
0,5
Initial rate
R1
R2= ½ R1
R3=1/4 R2
R4= 16 R3
R5=?
a) What is the reaction order with respect to A, to B
and to C?
b) What is the value R5 in terms of R1?
3. Hydroxide ion is involved in the mechanism of the
following reaction but is not consumed in the net
reaction:
-
OCl + I
-
[OCl-] ,M
OH-
[I-] , M
OI- + Cl[OH-], M
Rate
0,004
0,002
0,002
0,002
0,002
0,002
0,004
0,002
0,002
0,002
1,0
1,0
1,0
0,5
0,25
formation
OI-, Ms-1
4,8 x 10-4
4,8 x 10-4
2,4 x 10-4
4,8 x 10-4
9,6 x 10-4
a) From the data given, determine the order of
reaction with respect to OCl-, I- and OHb) What is the overall reaction order?
c) Write the rate equation and determine the value
of the rate constant, k.
4. The half life of the radioactive isotope phosphorus32 is 14,3 days. How long does it take for a sample
of phosphorus-32 to lose 99% of its radioactivity?
(It is a first order reaction)
5. In the first order reaction A
products
[A] = 0,724 M initially and 0,586 M after 16 min.
a) What is the value of the rate constant, k?
b) What is the half life of this reaction?
c) At what time will [A] = 0,185 M ?
d) What will [A] be after 2,5 h?
6. Three different sets of data of [A] are given below
for the reaction A
products (HINT:
Round off to two digits after comma at the end of
the calculation)
I
Time,
s
0
25
50
75
100
150
200
250
[A] ,
M
1,00
0,78
0,61
0,475
0,37
0,22
0,14
0,08
II
Time, [A] ,
s
M
0
1,00
25
0,75
50
0,50
75
0,25
100
0
III
Time, [A] ,
s
M
0
1,00
25
0,80
50
0,667
75
0,572
100
0,50
150
0,40
200
0,33
250
0,29
a) Which of these sets of data corresponds to a zero
order ; first order and second order reaction?
b) What is the approximate half life of the first order
reaction?
c) What is the approximate initial rate of the second
order reaction ?
d) What is the approximate rate of reaction at t= 75
s for the zero order, first order and second order
reaction?
e) What is the approximate concentration of A
remaining after 110 s in the zero order; first order
and second order reaction?
7. The decomposition of dimethyl ether at 504˚C is
(CH3)2O (g)
CH4 (g) + H2 (g) + CO (g)
The following data are partial pressures of dimethyl
ether (DME) as a function of time
t, s
PDME , mm
Hg
0
312
390
264
777
224
1195
187
3155
78,5
The reaction is first order.
a) What is the value of rate constant, k ?
b) What is the total gas pressure at 390 s ?
c) What is the total volume of the vessel containing
the gas mixture at t=1000 s, when there is 3,2 g
of CH4 present at 504˚C ( C=12 ; H=1 ; R= 0,082
atmL/molK
8. The change in the concentration of the reactant A with time in a second order
reaction is given:
Time (min)
0
20
40
60
a)
b)
c)
d)
Concentration(mol/L)
0,8
0,68
0,59
0,522
Calculate the rate constant(k) ( 4 p)
What is the unit of the rate constant (2 p)
What is the half life of the reaction? (4 p)
Assume the reaction occurs as 2 A
B, what is the time in hours required to
decompose 90% of A to B (4 p)
CHAPTER 10-CHEMICAL EQUILIBRIUM
1. What is the equilibrium constant for the reaction:
(Petrucci s.560)
½ N2(g) + ½ O2 (g)+1/2 Br2 (g)
Kc=?
NOBr (g)
If the equilibrium constants for the following reactions
are as follows:
2 NO(g)
N2 (g) + O2 (g) Kc = 2,4 x 1030
NO (g) + ½ Br2 (g)
NOBr (g) Kc =1,4
2. An equilibrium mixture at 1000 K contains 0,276
mol H2, 0,276 mol CO2, 0,224 mol CO and 0,224
mol H2O
CO2 (g) + H2 (g)
CO(g) + H2O (g)
Determine the value of Kc and Kp ( R= 0,082
atmL/molK)
3. The two common compounds PCl3 and PCl5 coexist
in equilbrium through the reaction
PCl3 (g)+ Cl2 (g)
PCl5 (g)
At 250˚C, an equilibrium mixture in a 2,5 L flask
contains 0,105 g PCl5, 0,22 g PCl3 and 2,12 g Cl2.
What are the values of Kc and Kp ? (P=31 ; Cl=35,5
; R= 0,082 atmL/molK)
4. A mixture consisting of 0,1 mol H2 and 0,1 mol I2 is
brought to equilibrium at 445˚C in a 1,5 L flask.
What are the equilibrium amounts of H2, I2 and HI?
H2 (g) + I2 (g)
2 HI (g) Kc= 50,2 at 445˚C
5. For the following reaction Kc= 2 at 1000˚C
2 COF2 (g)
CO2 (g) + CF4 (g)
If a 5 L mixture contains 0,105 mol COF2, 0,22 mol
CO2 and 0,055 mol CF4 at a temperature of 1000˚C
a) Will the mixture be at equilibrium?
b) If the gases are not at equilibrium, in what
direction will a net reaction occur?
c) What is the amount of each gas present at
equilibrium?
6. An aqueous solution that is 1,0 M in AgNO3 and 1,0
M in Fe(NO3)2 is allowed to come to equilibrium.
What are the equilibrium values of [Ag+] , [Fe2+]
and [Fe3+] ?
Ag+ (aq) + Fe2+ (aq)
= 2,98
Fe3+ (aq) + Ag (s) Kc
7. 1 mol each of SO2 and Cl2 are introduced into an
evacuated 1,75 L flask and the following
equilibrium is established at 303 K
SO2Cl2 (g)
SO2 (g) + Cl2 (g) Kp = 2,9 x
10-2
For this equilibrium calculate
a) The partial pressure of SO2Cl2 (g)
b) The total gas pressure
8. Explain how each of the factors affects the amount
of H2 present in an equilibrium mixture in the
reaction :
3 Fe (s) + 4 H2O (g)
Fe3O4 (s) + 4 H2 (g)
ΔH˚= - 150 kJ
a) Raise the temperature of the mixture
b) introduce more H2O (g)
c) double the volume of the container
d) add an appropriate catalyst
9.Starting with 3 mol SbCl3 and 1 mol Cl2 ,
equilibrium is established at 248˚C in a 2,5 L flask.
SbCl5 (g)
248˚C
SbCl3 (g) + Cl2 (g) KC= 0,025 at
a) What are the amounts in grams of SbCl5, SbCl3 and
Cl2 at the equilibrium?
b) Determine the total pressure at the equilibrium (R=
0,082 atmL/molK)
c) Assume now the volume of the container is doubled
after the equilibrium has been reached, determine Kp
and the mass percentage of Sb in the gas mixture for the
final equilibrium
(Sb= 121,75 g/mol Cl=35,5 g/mol )
CHAPTER 11- ACIDS AND BASES
+
1. Calculate [H3O ] and pH in saturated Ba(OH)2 (aq)
[containing 39 g Ba(OH)2 ∙ 8 H2O per liter]
(Ba=137,3 ; O=16 ; H=1)
2. What volume of concentrated HCl (aq) that is 36%
HCl by mass and has a density of 1,18 g/mL is
required to produce 8,25 L of a solution with a
pH=1,75
3. For each of the following identify the acids and
bases in both the forward and reverse reactions?
a) HClO2 + H2O
H3O+ + ClO2b)
OCl- + H2O
HOCl + OH-
c)
NH3 + H2PO4-
NH4+ + HPO42-
4.A 0,5 M solution of the fluoroaceticacid is found to
have a pH=1,46. Calculate Ka of fluoroacetic acid
CH2FCOOH (aq) + H2O
H3O+ (aq) +
CH2FCOO- (aq) Ka =?
5. What is the molarity of an aqueous o-chlorophenol,
HOC6H4Cl, solution that is found to have a
pH=4,86?
HOC6H4Cl + H2O
H3O+ + - OC6H4Cl
pKa = 8,49
6. What must be the molarity of an aqueous solution of
NH3 if it is to be 2% ionized? Kb = 1,8x10-5
7. What is the percent ionization of trichloroacetic acid
in an 0,05 M HC2Cl3O2 solution?
HC2Cl3O2 + H2O
H3O+ + C2Cl3O2-
CHAPTER 12-ELECTROCHEMISTRY
1. Balance the following equations for redox reactions
occuring in acidic solutions
a) MnO4- + I- + H+
Mn2+ + I2(s) + H2O
b) BrO3- + N2H4 + H+
Br- + N2 + H2O
c) UO22+ + NO3- + H+
UO22+ + NO (g) +
H 2O
2. Balance the following equations for redox reactions
occuring in basic solutions
a) CN- + MnO4- + OHMnO2 (s) + CNO + H2O
b) Fe(OH)2 (s) + O2 (g) + OHFe(OH)3 +
H 2O
c) [Fe(CN)6]3- + N2H4 + OH[Fe(CN)6]4- +
N 2 + H 2O
d) As2S3 + OH- + H2O2
AsO43- + H2O +
SO423. In each of the following examples, sketch a voltaic
cell that was the given reaction. Label the anode and
cathode. Indicate the direction of electron flow,
write a balanced equation for the cell reaction,
calculate E˚cell
a) Cu (s) + Fe3+ (aq)
Cu2+ (aq) + Fe2+ (aq)
Fe3+ + 1 eFe2+ E˚cell = + 0,771 V
Cu2+ + 2 eCu (s) E˚cell = + 0,337 V
b) Pb2+ is displaced from solution by Al (s)
c) Cl2 is reduced to Cl- and Fe is oxidized to Fe2+
(aq)
4. In a voltaic cell Al(s) is oxidized to Al3+ and Zn2+ is
reduced to Zn. The reduction electrode potentials
are
Al3+ + 3 eAl (s) E˚cell = - 1,676 V
Zn2+ + 2 eZn (s) E˚cell = - 0,763 V
a) Determine the cathode and anode
b) In which direction does the electron flow occur?
c) Calculate E˚cell for the net reaction
d) Write the net reaction
e) Calculate ΔG for the net reaction
5. Calculate Ecell for the following voltaic cell using
the Nernst equation
Al(s)/Al3+ (0,36 M) // Sn4+ (0,086M) , Sn2+ (0,54 M)
Pt
Al3+ + 3 eAl E˚= - 1,676 V
Sn4+ + 2 eSn2+ E˚= + 0,154 V
6. The voltaic cell indicated below has E˚cell = 0,108
V. What is the pH pf the unknown solution?
Cathode: 2 H+ + 2 eH2 (g, 1 atm) E˚cell=
0V
Anode: H2
2 H+ + 2 e- E˚cell= 0 V
Net reaction : 2 H+ (0,1 M)
2 H+ (x M)
7. Given the following redox reaction:
Cathode: Cu2+ + 2 eCu(s)
Anode: 2 H2O
O2 (g) + 4 H+ + 4 ea) For how long would the electrolysis have to be
carried out with a current of 2,13 A at a Pt anode
to produce 2,62 L of O2 (g) measured at 26,2˚C
and 738 mm Hg pressure?
b) What is the amount in grams of Cu(s) produced?
( 1 mol e- = 96485 C ; R= 0,082 atmL/molK; Cu=
63,5 g/mol ; 1 atm=760 mm Hg)