The vapor pressure of ethanol is 54.68 mm Hg at 25oC.

How many grams of chlorophyll , C55H72MgN4O5, a nonvolatile, nonelectrolyte (MW = 893.5 g/mol), must be added to 207.6 grams of ethanol to reduce the vapor pressure to 53.60 mm Hg ?

ethanol = CH3CH2OH = 46.07 g/mol.

delta P = 54.68-53.60 = 1.08 mm

delta P = 1.08 = Xchlor*Posolvent
1.08 = Xchlor*54.68
Solve for X chlorophyll

Then Nc = mols chlorophyll
and Netoh = mols ethanol

(Nc)/(Nc+Netoh) = X chlorophyll from above.
Solve for Nc

Then convert to grams.
g chlorophyll = mols chlorophyll x molar mass chlorophyll.
Post your work if you get stuck.

To solve this problem, we can use Raoult's law, which states that the vapor pressure of a solution is proportional to the mole fraction of the solvent present.

The mole fraction of ethanol (CH3CH2OH) can be calculated using the formula:

Mole fraction = moles of ethanol / (moles of ethanol + moles of chlorophyll)

First, let's calculate the moles of ethanol in 207.6 grams using its molar mass:

Moles of ethanol = Mass of ethanol / Molar mass of ethanol
Moles of ethanol = 207.6 g / 46.07 g/mol
Moles of ethanol = 4.51 mol

Now, let's calculate the moles of chlorophyll that need to be added to achieve the desired vapor pressure.

To do this, we will use the formula for the mole fraction:

Mole fraction ethanol = Moles of ethanol / (Moles of ethanol + Moles of chlorophyll)

Since we want the vapor pressure of the solution to be equal to 53.60 mm Hg, we can set up the following equation using Raoult's law:

53.60 mm Hg = Mole fraction ethanol × Vapor pressure of ethanol

Let's insert the known values into the equation:

53.60 mm Hg = (4.51 mol / (4.51 mol + moles of chlorophyll)) × 54.68 mm Hg

Now, let's solve for the moles of chlorophyll:

moles of chlorophyll = 4.51 mol * (1 - (53.60 mm Hg / 54.68 mm Hg))
moles of chlorophyll = 4.51 mol * (1 - 0.9798)
moles of chlorophyll = 0.1002 mol

Now that we have the moles of chlorophyll needed, let's calculate the mass of chlorophyll:

Mass of chlorophyll = Moles of chlorophyll × Molar mass of chlorophyll
Mass of chlorophyll = 0.1002 mol × 893.5 g/mol
Mass of chlorophyll ≈ 89.46 g

Therefore, approximately 89.46 grams of chlorophyll need to be added to 207.6 grams of ethanol to reduce the vapor pressure to 53.60 mm Hg.

To solve this problem, we need to use Raoult's law, which relates the vapor pressure of a solvent above a solution to the mole fractions of the solute and solvent. The formula for Raoult's law is as follows:

P = Xsolute * Psolute

Where P is the vapor pressure of the solution, Xsolute is the mole fraction of the solute, and Psolute is the vapor pressure of the pure solute.

First, let's calculate the mole fraction of ethanol (the solvent) in the solution. We can do this using the following formula:

Xethanol = moles of ethanol / total moles

The given mass of ethanol is 207.6 grams, and its molar mass is 46.07 g/mol. Therefore, the number of moles of ethanol can be calculated as:

moles of ethanol = mass of ethanol / molar mass of ethanol

moles of ethanol = 207.6 g / 46.07 g/mol

moles of ethanol = 4.51 mol

Since we know that ethanol is the solvent, the mole fraction of ethanol is equal to 1. Therefore, Xethanol = 1.

Now, we can rearrange Raoult's law to solve for Xsolute:

Xsolute = P / Psolute

Given that the vapor pressure of ethanol at 25°C is 54.68 mm Hg and we want to reduce it to 53.60 mm Hg, we can calculate Xsolute as follows:

Xsolute = 53.60 mm Hg / 54.68 mm Hg

Xsolute = 0.9793

Next, we can use the mole fraction to calculate the moles of solute (chlorophyll) required to achieve the desired vapor pressure. We can use the same equation as before:

moles of chlorophyll = Xsolute * total moles

The total moles in the solution is the sum of the moles of ethanol and the moles of chlorophyll. Let's calculate it:

total moles = moles of ethanol + moles of chlorophyll

Since we are trying to find the moles of chlorophyll, we can rearrange the equation:

moles of chlorophyll = total moles - moles of ethanol

Now, we need to calculate the total moles. The moles of ethanol (solvent) is 4.51 mol. We can calculate the moles of chlorophyll as follows:

moles of chlorophyll = total moles - 4.51 mol

Finally, we can convert the moles of chlorophyll to grams using its molar mass:

mass of chlorophyll = moles of chlorophyll * molar mass of chlorophyll

Given that the molar mass of chlorophyll is 893.5 g/mol, we can calculate the mass of chlorophyll required to achieve the desired vapor pressure.