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Experiment 11. Oxidizing properties of nitrogen (III).
Add 4–5 drops of
sulfuric acid and 4–5 drops of sodium iodide to 4–5 drops of a solution of
sodium nitrite NaNO
2.
The liberated iodine is detected by the addition of a
starch solution. Write the equation of the reaction, select the coefficients by the
electronic balance method.
Experiment 12. Reducing properties of nitrogen (III).
Add 4–5 drops
solution of sulfuric acidto 3–4 drops of sodium nitrite solution NaNO
2.
Then
add 5 drops of KMnO
4
solution. What’s happening? Write the equation of the
reaction, arrange the coefficients by the electronic balance method.
Experiment 13. Instability of thiosulfate in an acid medium
. Add 5–6 drops
of a solution of sodium thiosulfate Na
2
S
2
O
3
and 3–4 drops of a 1M solution of
sulfuric acid to the tube. What is observed? Write the equation for the reaction
of sodium thiosulfate with sulfuric acid.
LESSON 11.
ELECTRODE AND REDOX – POTENTIALS
Required base level.
Typical oxidants and reducing agents. The concept of a galvanic cell,
electromotive force
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. Calculation of the pH of strong and weak electrolytes.
Questions for the preparation for the lesson.
1. Mechanism of the appearance of the electrode potential. Element of
Daniel-Jacobi. The Nernst equation.
2. Oxidation-reduction system: types of oxidation-reduction systems. The
Nernst-Peters equation.
3. The mechanism of occurrence of redox potential. Factors affecting redox
potentials: the influence of the ligand environment of the central atom on
the value of the redox potential.
4. Hydrogen electrode: device, application. The Nernst equation for the
hydrogen electrode.
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measurement with hydrogen electrode. Electrode-
potential seriesof metals.
5. Ion-selective electrodes: glass electrode. The Nernst equation for a glass
electrode.
6. Determination of pHvalue of solutions with hydrogen and glass electrodes.
7.
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of electrochemical reactions. The constant of the oxidation-reduction
process.
Input test-control on the topic «Electrode and redox potentials».