Concept explainers
(a)
Interpretation:
The total vapor pressure of the solutions at
Concept Introduction:
The equilibrium between a liquid and its vapor produces a characteristic vapor pressure for each substance that depends on the temperature. The lowering of the vapor pressure is caused by a lesser ability of the solvent to evaporate, so equilibrium is reached with a smaller concentration of the solvent in the gas phase. The vapor pressure of a solution is expressed using Raoult’s law:
The vapor pressure of the solvent
Mole fraction: Mole fraction of a substance in a solution is the number of moles of that substance divided by the total number of moles of all substances present. The formula is,
Dalton’s Law:
The total pressure of a gas mixture is the sum of the partial pressures of its component gases.
Where
The partial pressure of the gas can be obtained by multiplying the total pressure of the mixture with the percent of the gases present in the mixture.
(a)
Answer to Problem 5C.12E
The total vapor pressure of the solution at
The mole fraction of hexane in the vapor phase above the solution is
The mole fraction of cyclohexane in the vapor phase above the solution is
Explanation of Solution
Total vapor pressure of the solution:
Given,
The vapor pressure of pure hexane at
The vapor pressure of pure cyclohexane at
Moles of hexane is
Moles of cyclohexane is
The mole fraction of hexane is calculated as,
Mole fraction of hexane=
Mole fraction of hexane=
Mole fraction of hexane=
The mole fraction of hexane is
The vapor pressure of hexane is calculated as,
The vapor pressure of hexane is
The mole fraction of cyclohexane is calculated as,
Mole fraction of cyclohexane=
Mole fraction of cyclohexane=
Mole fraction of cyclohexane=
The mole fraction of cyclohexane is
The vapor pressure of cyclohexane is calculated as,
The vapor pressure of cyclohexane is
The total vapor pressure is calculated using Dalton’s law.
The vapor pressure of hexane
The vapor pressure of cyclohexane
The total vapor pressure of the solution at
Mole fraction of hexane in vapor phase:
The vapor pressure of hexane is
The total vapor pressure of the solution at
The mole fraction of hexane in the vapor phase is calculated as
The mole fraction of hexane in the vapor phase above the solution is
Mole fraction of cyclohexane in vapor phase:
The vapor pressure of hexane is
The total vapor pressure of the solution at
The mole fraction of cyclohexane in the vapor phase is calculated as
The mole fraction of cyclohexane in the vapor phase above the solution is
(b)
Interpretation:
The total vapor pressure of the solutions at
Concept Introduction:
Refer to part (a).
(b)
Answer to Problem 5C.12E
The total vapor pressure of the solutions at
The mole fraction of hexane in the vapor phase above the solution is
The mole fraction of cyclohexane in the vapor phase above the solution is
Explanation of Solution
Given,
The vapor pressure of pure hexane at
The vapor pressure of pure cyclohexane at
Grams of hexane is
Grams of cyclohexane is
The moles of hexane is calculated as,
Moles of hexane=
Moles of hexane=
The moles of cyclohexane is calculated as,
Moles of cyclohexane=
Moles of cyclohexane=
The mole fraction of hexane is calculated as,
Mole fraction of hexane=
Mole fraction of hexane=
Mole fraction of hexane=
The mole fraction of hexane is
The vapor pressure of hexane is calculated as,
The vapor pressure of hexane is
The mole fraction of cyclohexane is calculated as,
Mole fraction of cyclohexane=
Mole fraction of cyclohexane=
Mole fraction of cyclohexane=
The mole fraction of cyclohexane is
The vapor pressure of cyclohexane is calculated as,
The vapor pressure of cyclohexane is
The total vapor pressure is calculated using Dalton’s law.
The vapor pressure of hexane
The vapor pressure of cyclohexane
The total vapor pressure of the solution at
Mole fraction of hexane in vapor phase:
The vapor pressure of hexane is
The total vapor pressure of the solution at
The mole fraction of hexane in the vapor phase is calculated as
The mole fraction of hexane in the vapor phase above the solution is
Mole fraction of cyclohexane in vapor phase:
The vapor pressure of hexane is
The total vapor pressure of the solution at
The mole fraction of cyclohexane in the vapor phase is calculated as
The mole fraction of cyclohexane in the vapor phase above the solution is
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Chapter 5 Solutions
ACHIEVE/CHEMICAL PRINCIPLES ACCESS 1TERM
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