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?
5. Complete the table given below
Element
Sn
Ag
I
Ar
W
Cs+
Cu2+
Z
50
53
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
24b) Cr2O7
g) XeO6
l) 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
g) I and Xe
h)Se and Cl
c)S and As
d)Ba and Sr
e)Cs and Ba
f)Cl and I
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)
b)
c)
d)
e)
Arrange the ions in the increasing order of atomic radius
Which of them is a noble gas?
Which of them has the highest negative electron affinity?
Which of them has positive electron affinity?
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)
b)
c)
d)
e)
IA
IIB
III B
4A
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)
b)
c)
d)
e)
The element makes ionic bonds with halogenes
It is a transition element
Its ionization energy is greater than Iodine
The atomic radius of the element is greater than that of its ion X2The element X is paramagnetic
6. 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)
b)
c)
d)
e)
IIA
IIIB
VIII A
VIB
VII B
What is the oxidation state of the element X in the compound XO2
a)
b)
c)
d)
e)
-3
+4
+2
-1
+7
Which of the statements described below is false?
a)
b)
c)
d)
e)
The element X has a first ionization energy lower than that of Kr
The element X has 5 electrons in its d orbitals.
The element X is paramagnetic, but its ion X7+ is diamagnetic
Its oxides have acidic character
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)
j)
k)
l)
m)
Lithiumnitride
Gold(III)oxide
Cobalt(II)nitrite
Iron(II)oxide
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.
II.
H2S (g) + 3/2 O2 (g)
CS2 (l) + 3 O2(g)
H2O (l) + SO2 (g) ΔH˚= - 562,6 kJ
CO2 (g) + 2 SO2 (g) ΔH˚= - 1075,2 kJ
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)
II.
4 NH3 (g) + 3 O2 (g)
4 N2 (g) + 3 H2O (l) ΔH˚= - 1010 kJ
2 N2 (g) + 6 H2O (l) ΔH˚= - 1531 kJ
35. Determine the enthalpy change of reaction
B2H6 (g) + 6 Cl2 (g)
I.
BCl3 (g) + 3 H2O (l)
2 BCl3 (g) + 6 HCl (g)
H3BO3 (s) + 3 HCl (g) ΔH˚= - 112,5 kJ
II.
III.
B2H6 (g) + 6 H2O (l)
½ H2 (g) + ½ Cl2 (g)
2 H3BO3 (s) + 6 H2 (g) ΔH˚= - 493,4 kJ
HCl
ΔH˚= - 92,3 Kj
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
39.
CHAPTER 8 : SOLUTIONS
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.
41.
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)
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
[A], M
[B], M
[C] ,M
Initial rate
1
1,4
1,4
1
R1
2
0,7
1,4
1
R2= ½ R1
3
0,7
0,7
1
R3=1/4 R2
4
1,4
1,4
0,5
R4= 16 R3
5
0,7
0,7
0,5
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-
OH-
OI- + Cl-
[OCl-] ,M
[I-] , M
[OH-], M
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
Rate 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 phosphorus-32 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
II
III
Time, s
[A] , M
Time, s
[A] , M
Time, s
[A] , M
0
1,00
0
1,00
0
1,00
25
0,78
25
0,75
25
0,80
50
0,61
50
0,50
50
0,667
75
0,475
75
0,25
75
0,572
100
0,37
100
0
100
0,50
150
0,22
150
0,40
200
0,14
200
0,33
250
0,08
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
CHAPTER 10-CHEMICAL EQUILIBRIUM
1. What is the equilibrium constant for the reaction:
½ N2(g) + ½ O2 (g)+1/2 Br2 (g)
(Petrucci s.560)
NOBr (g) Kc=?
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)
Fe3+ (aq) + Ag (s)
Kc = 2,98
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)
SbCl3 (g) + Cl2 (g) KC= 0,025 at 248˚C
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) + H2O
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) + OH
Fe(OH)3 + H2O
3c) [Fe(CN)6] + N2H4 + OH
[Fe(CN)6]4- + N2 + H2O
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
2+
b) Pb 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
2+
Zn + 2 e
Zn (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
4+
Sn + 2 e
Sn2+ 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= 0 V
+
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)