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IV the Latin American Olympic Games of Chemistry
Theoretical test 1
Theoretical test 3
A student of Chemistry made electrolysis of the water by means of the described equipment in the figure, where are the states initial and final of the process. The process was made previous saturation in gases hydrogen and oxygen. The presented/displayed diagram is not on scale:
The made conditions of work and measures are indicated next:
Temperature: 20oC
Intensity of current: 0,100A
Atmospheric
pressure: 560 mmHg (7,464x104 Pa)
Time: 20 min.
Density solution H2SO4:
1,015 g/mL
Volume of hydrogen: 20,16 cm3
Load of the electron:
1,602x10-19 C
Value height h2: 290 mm
Density of mercury: 13,6 g/cm3
Water steam pressure: 17,5 mmHg (2,332x103 Pa)
Density of mercury: 13,6
g/cm3
Values for the constant R: 0,082 L.s atm./mol. K 8.314 J/mol. K 8.314
kPa. dm3./mol.
K Q = I x t,
where: Q: amount of current month (in coulombs).
I: intensity of current (amperes) t: time (seconds)
Express the results with the suitable significant numbers.
With base in the previous information it responds the following questions:
1, Equations of reactions of the process:
a) cathodic:
b) anodic:
2. Calculate the amount (soft) of produced hydrogen supposing ideal behavior of the gas:
MASSES OF I HYDROGENATE: _____
á. Considering the information available, it calculates the value of the constant of Avogadro:
4a. Considering the information available, it calculates the experimental value of the constant of Faraday:
Constant of Faraday: _____
5. If the oxygen produced during the process is made react with excess of sulfur, what volume of gaseous sulfur dioxide is obtained to the same conditions in which the hydrogen in the process took shelter of electrolysis?
a) Equation of the reaction.
b) Calculation of the produced volume of SO2(g), supposing ideal behavior of the gas:
VOLUME OF SULFUR DIOXIDE ___________
Theoretical test 3
A sample of 1.802 g. of a compound that contains only carbon, hydrogen and oxygen, was burned totally in the presence of 3.961 oxygen and 0.7206 CO2 g. was obtained and g. of H2O. When dissolving the same amount of sample in water until obtaining 100 mL of solution, this one presents/displays a osmótica pressure of 2.460 atmospheres to 27oC. To determine the molecular formula of the compùesto. To express the final result with three significant numbers.
