Name:
Laboratory group:
T.1: DETERMINATION OF THE MOLECULAR MASS OF A LIQUID USING THE STEAM
DISTILLATION METHOD
1) Calibration of the temperature probe with pure water
𝒆𝒙𝒑𝒕
𝑻𝒃
(𝑯𝟐 𝑶):
Atmospheric pressure (from barometer):
Values from tabulated data
Pv(H2O)
Tb
Value 1
Value 2
Boiling temperature at the lab pressure (from interpolation):
Temperature probe error:
2) Determination of molecular mass for cyclohexanone
𝒆𝒙𝒑𝒕
𝑻𝒃
(𝑯𝟐 𝑶 + 𝒄𝒚𝒄𝒍𝒐𝒉𝒆𝒙𝒂𝒏𝒐𝒏𝒆):
Corrected boiling temperature of the mixture:
Tb
Pv(H2O)
Value 1
Value 2
Water Pv at distillation temperature:
Total
Organic phase
Aqueous phase
Volume
Cyclohexanone (WC)
Water (WW)
Mass
Mass corrected
(solubility cyclohexanone in water)
MC =
Discussion on the results:
=
g·mol-1
Name:
Laboratory group:
T.2: DETERMINATION OF THE MOLECULAR MASS OF A SOLUTE USING THE
FREEZING POINT DEPRESSION METHOD
Melting temperature pure solvent (𝑻𝒇∗ )
Experiment:
Tabulated:
Melting temperatures for solutions (𝑻𝒇 ). Fill the table after considering points 1 and 2
%
Naphthalene
1.75%
2.00%
2.25%
2.75 %
3.00%
Wsolute
Wsolvent
Tf
T = (Tf*-Tf
Msolute
)
1. Determine Kf using the equation given in the laboratory guide and compare with the value reported in the
Handbook of Chemistry and Physics. Decide which is the most convenient value to use in the calculations of
T and explain why.
2. Analyze in detail and discuss which is the optimal Tf* to use in calculations.
Molecular mass obtained for naphthalene:
Discussion on the results (add cooling temperature curves):
Name:
Laboratory group:
E.1: REDUCTION POTENTIAL FOR THE Pt|Fe2+,Fe3+ ELECTRODE
1) Preparations of solutions
Calculations to prepare the solution of H2SO4 1M:
Calculations to prepare the solution of Fe2+ 0.1M:
Grams of Fe2+ salt:
Do we use analytical balance or the load cell balance?
Calculations to prepare the solution of Fe3+ 0.1M:
Do we use analytical balance or the load cell balance?
[Fe3+]expt.:
Weight:
2) Determination of [Fe2+] / [Fe3+] redox potential
Titration of Fe2+: Summarize the calculations performed to estimate the volume required for the titration of
10 ml of KMnO4 (0.02 M). Give the reactions involved.
Titration
VFe(II)
VKMnO4
[Fe2+]expt :
MFe(II)
3) Determination of the Galvanic cell potential
As explained in the laboratory guide we can use different points to determine the value of E. Please give
in the following table some selected values you have used to find E and E0Pt|Fe2+, Fe3+
Experiment
1st measures
2on measures
Vadded
[Fe2+]/ [Fe2+]+ [Fe3+]
E
E =_______________
E0 Pt|Fe2+, Fe3+ = ___________
Discussion on the results (add tables and representations):
Name:
Laboratory group:
E.2 THE ELECTROLYSIS OF WATER:
1. Write the overall reaction and the two half-reactions. All equations must be correctly balanced
(under laboratory conditions) in both mass and charge.
Oxidation half-reaction:
Reduction half-reaction:
Overall reaction:
2. Make a diagram of the electrolytic cell indicating the anode, the cathode, the direction of the
current and the electrons, the species present, etc. Calculate the emf of the reaction as well as the
Gibbs free energy of the overall process from the values of the theoretical standard potential for
each of the half-reactions.
3. What is the first potential where you observed formation of H2 and O2? Give the values for the
different combinations of electrodes. Is this close to what we would expect from standard reaction
potentials? Reason why.
Electrode combination
E start of production
4. Share the data collected for each electrode combination and record it in the table below.
Volumes and time correspond to the difference between the last and the first measurement.
Electrode combination:
Total time(min)
Mean of E (V)
Mean of I (A)
Volum H2 (ml)
Volum O2 (ml)
Name:
Laboratory group:
5. What factors affect gas production?
In the combination of a graphite and a Pt electrode, does it matter where we put each
electrode? Because?
Without taking into account the cost, and taking into account the size of the electrode, which
material is better for the anode and which for the cathode?
The electrodes you used are worth approximately 10 euros for graphite and 80 euros for Pt,
which combination is better to use?
6. From the Intensity we can know how many moles of electrons have circulated through the cell,
how many moles of hydrogen and oxygen should have been theoretically generated? Using the ideal
gas equation, what volume should they have? Compare this with what has been observed in
practice.
7. A hydrogen car uses 0.9 kg of H2 per 100 km. If this hydrogen was generated with the best of
your cells, what would be the economic cost? Use the electricity market prices of the day. Compare
that with the cost of a diesel car that consumes 5 litres of diesel per 100 km. Use the diesel prices of
the day.
Name:
Laboratory group:
H: TRANSPORT NUMBER. MÈTODE DE HITTORF
Compile some data useful for calculations
Cell solution weights (g)
Anode
Cathode
Initial
Final
Thiosulphate solution
Weight (g):
Volume (ml):
Titrations
Weight solution (g) Volume thisulfate (ml)
Initial solutions
1
2
3
Final solutions
1
2
3
Anodic solution
Total weight (g):
Discussion on the results: