Point
General
Final test 2009.12.03.
Chemistry
Name:
Max
32p
In 100 g H2O dissolve 0.635 g of FeCl2. The density of the solution is 1.012 g/cm3.
1. The osmotic pressure at 23 °C:
(4p)
The molar boiling point increase of the water is 0.52 °C·mol/kg H2O.
Ar(Fe): 56.0; Ar(Cl): 35.5.
2. The boiling point of the solution:
(6p)
Next we add H2SO4 and oxidize the FeCl2 completely by KMnO4:
3.
MnO4− +
Fe2+ +
H+ =
Mn2+ +
Fe3+ +
H2O
(3p)
4.
(3p)
MnO4− +
Cl− +
H+ =
Mn2+ +
Cl2 +
H2O
5. What is the volume of the Cl2 gas at T=25 °C and p=101.41 kPa?:
The Cl2 gas reacts with NaI solution (bubbling):
6.
I− +
Cl2 +
7.
IO3− +
8.
Na2S2O3 +
9.
Br- +
H2O
=
IO3− +
H+
=
I2 +
I− +
I2
Cr2O72- +
=
Na2S4O6 +
H2SO4 →
Br2 +
Cl− +
(4p)
H+
(3p)
H2O
(3p)
NaI
(3p)
Cr3+ +
SO42- +
H 2O
(3p)
Point
General
Final test 2009.12.03.
Chemistry
Name:
Max
32p
Name the following compounds (1p for each, total 10 points):
10. NO
11. NO2
12. N2O
13. N2O3
14. N2O4
15.NaClO
16. KClO2
17. HClO3
18. HClO4
19. CaSO3
Reaction: N2O4 (g)  2 NO2 (g).
Ar(N): 14; Ar(O): 16.
Volume = 1 dm3, T= 70 °C, the initial mass of the N2O4 is 9.2 g. We wait for the dissociation
equilibrium and in the equilibrium we measure the total pressure of 399.24 kPa
Calculate equilibrium constant with mols (Kn), with concentrations (Kc), and with
pressure (Kp), the degree of dissociation (), the volume %, and the average molar
mass.
20. Kn =
(4p)
21. Kc =
(4p)
22. Kp =
(4p)
23.  =
(4p)
24. volume % =
25. average molar mass:
N2O4 (g)
NO2
(4p)
(2p)
General
Final test 2009.12.03.
Chemistry
Point
Max
Name:
34p
2+
Calculate the following non standard electrode potentials if °(Cu/Cu )= +0,340 V:
26. Metal Cu in 0.05 M CuSO4 solution:
(4p)
27. Metal Cu in saturated Cu3(PO4)2 solution:
(6p)
Ksp[Cu3(PO4)2]= 1.08 x 10
−13
28. Metal Cu in saturated Cu(OH)2 solution at pH=9:
(6p)
Ksp[Cu(OH)2]= 5.0·x 10−18
29. Hydrogen electrode in pH 12.5 NaOH solution:
(6p)
30. Hydrogen electrode in 0.02 M weak acid solution:
Ks(weak acid)=1.0 x 10−4
(8p)
31. Connect the electrodes in 29. and 30. What is the cell potential? Which electrode
is the cathode and which electrode is the anode?
(4p)