Calculate the vapor pressure at 25 C of hexane above the solution. The vapor pressure of pure hexane at 25 C is 151 torr.
A solution contains naphthalene ({\rm{C}}_{10} {\rm{H}}_8) dissolved in hexane ({\rm{C}}_6 {\rm{H}}_{14}) at a concentration of 12.17 \% naphthalene by mass.
The first paragraph makes sense but there is no question. I can't decipher the second paragraph. If the second paragraph is supposed to give information to calculate the concn of naphthalene, then what you want is
Psolution = Xhexane*Pohexane
To calculate the vapor pressure at 25°C of hexane above the solution, we need to apply Raoult's law.
Raoult's law states that the partial pressure of a component in a solution is equal to the mole fraction of that component multiplied by its vapor pressure in its pure state.
First, let's calculate the mole fraction of hexane in the solution:
- We know that the concentration of naphthalene (C10H8) in the solution is 12.17% by mass.
- Therefore, the concentration of hexane (C6H14) in the solution is 100% - 12.17% = 87.83% by mass.
- Convert these mass percentages to mole fractions using the molar masses of naphthalene and hexane:
- Molar mass of naphthalene (C10H8) = 128.18 g/mol.
- Molar mass of hexane (C6H14) = 86.18 g/mol.
- Mass of naphthalene (C10H8) = 12.17 g (given).
- Mass of hexane (C6H14) = 87.83 g (calculated).
- Moles of naphthalene (C10H8) = mass of naphthalene / molar mass of naphthalene.
- Moles of hexane (C6H14) = mass of hexane / molar mass of hexane.
- Mole fraction of hexane = moles of hexane / (moles of hexane + moles of naphthalene).
Now that we have the mole fraction of hexane in the solution, we can use Raoult's law to calculate the vapor pressure of hexane above the solution.
Let's assume the vapor pressure of hexane above the solution is P_hexane(solution).
According to Raoult's law:
P_hexane(solution) = mole fraction of hexane * P_hexane(pure).
Given:
- P_hexane(pure) = 151 torr (vapor pressure of pure hexane at 25°C).
Now, substitute the values into the equation to calculate the vapor pressure of hexane above the solution:
P_hexane(solution) = mole fraction of hexane * P_hexane(pure).
After calculating the mole fraction of hexane, plug it into the equation with the given vapor pressure of pure hexane at 25°C to find the vapor pressure of hexane above the solution.
To calculate the vapor pressure of hexane above the solution, we need to apply Raoult's law. According to Raoult's law, the vapor pressure of a solvent above a solution is equal to the mole fraction of the solvent multiplied by its vapor pressure in its pure state.
First, we need to calculate the mole fraction of hexane in the solution using the concentration of naphthalene by mass.
1. Calculate the mass of naphthalene in the solution:
Mass of naphthalene = (concentration of naphthalene) × (mass of solution)
= 0.1217 × (mass of solution)
2. Calculate the mass of hexane in the solution:
Mass of hexane = (mass of solution) - (mass of naphthalene)
3. Calculate the moles of naphthalene:
Moles of naphthalene = (mass of naphthalene) / (molar mass of naphthalene)
4. Calculate the moles of hexane:
Moles of hexane = (mass of hexane) / (molar mass of hexane)
5. Calculate the mole fraction of hexane:
Mole fraction of hexane = Moles of hexane / (Moles of hexane + Moles of naphthalene)
Now, we can calculate the vapor pressure of hexane above the solution using Raoult's law:
Vapor pressure of hexane = Mole fraction of hexane × Vapor pressure of pure hexane at 25°C
Please provide the molar mass of naphthalene and hexane to proceed with the calculation.