GASES+Free+Response+worksheet - AP Gas Law Free Response...

AP* Gas Law Free Response Questions
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C. Calculate
the percentage of sodium formate in the original mixture.
1971
At 20 ° C the vapor pressure of benzene is 75 torr, and the vapor pressure of toluene is 22 torr. Solutions in both
parts of this question are to be considered ideal.
(a) A solution is prepared from 1.0 mole of biphenyl, a nonvolatile solute, and 49.0 moles of benzene. Calculate
the vapor pressure of the solution at 20 ° C.
(b) A second solution is prepared from 3.0 moles of toluene and 1.0 mole of benzene. Determine the vapor
pressure of this solution and the mole fraction of benzene in the vapor.
1972
A 5.00 gram sample of a dry mixture of potassium hydroxide, potassium carbonate, and potassium chloride is
reacted with 0.100 liter of 2.0 molar HCl solution.
(a) A 249 milliliter sample of dry CO
2
gas, measured at 22 ° C and 740 torr, is obtained from the reaction. What is
the percentage of potassium carbonate in the mixture?
(b) The excess HCl is found by titration to be chemically equivalent to 86.6 milliliters of 1.50 molar NaOH.
Calculate the percentages of potassium hydroxide and of potassium chloride in the original mixture.
1973
A 6.19 gram sample of PCl
5
is placed in an evacuated 2.00 liter flask and is completely vaporized at 252 ° C.
(a) Calculate the pressure in the flask if no chemical reaction were to occur.
(b) Actually at 252 ° C the PCl
5
is partially dissociated according to the following equation:
PCl
5
( g ) → PCl
3
( g ) + Cl
2
( g
The observed pressure is found to be 1.00 atmosphere. In view of this observation, calculate the partial
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