A bottle of wine contains 13.1% ethanol by volume. The density of ethanol (C2H5OH) is 0.789 g/cm3. Calculate the concentration of ethanol in wine in terms of mass percent and molality.

mass percent
_______%
molality
______mol/kg

Thanks

I suppose you are to assume the density of the ine to be 1.00. I looked up the density of wine on the Internet and found that it varies between about 0.990 to 1.01 so 100 mL would have a mass of 99 to 101 which isn't that far from 100.

So 13.1% v/v means 13.1 mL ethanol/100 mL solution.
13.1 mL x 0.789 g/mL = 10.34 grams. Check me on that.
Then the solution, with a density of 1.00 will have a mass of 100 grams. So (10.34 g/100 g soln )*100 = 10.34 mass percent.
Molality = mols/kg solvent.
# mols ethanol in 10.34 g = 10.34/46 = 0.225 mol.
We had the ethanol in 100 g and 10.35 of that was ethanol; therefore, the mass of the solvent was 100 - 10.3 = 89.7 g or 0.0897 kg.
molality = 0.225/0.0897 = ??

Check my calculations. Check my thinking. You may need to do the molar mass ethanol again since I estimated it at 46.

againnn sorry :(

A 2.30 g sample of a large boimolecule was dissolved in 23.0 g of carbon tetrachloride. The boiling point of this solution was determined to be 77.85°C. Calculate the molar mass of the biomolecule. For carbon tetrachloride, the boiling point constant is 5.03°C·kg/mol, and the boiling point of pure carbon tetrachloride is 76.50°C.
_______ g/mol

delta T = Kb*molality

You know delta T (77.85-76.50), you know Kb, calculate molality.

molality = # mols/kg solvent. You know molality and kg solvent. Calculate # mols.

#mols = grams/molar mass. You know # mols and grams, calculate molar mass.

To calculate the concentration of ethanol in wine in terms of mass percent, we need to determine the mass of ethanol in the wine and divide it by the total mass of the wine, then multiply by 100 to get the percentage.

First, let's calculate the mass of ethanol in the wine. We know that the volume percentage of ethanol is 13.1% and the density of ethanol is 0.789 g/cm3. However, we'll need the density of the wine as well.

Assuming the density of the wine is 1 g/cm3 (since wine typically has a density close to water), we can calculate the mass of ethanol using the following formula:

Mass of ethanol = Volume of ethanol x Density of ethanol
= (13.1/100) x (1 g/cm3)
= 0.131 g

Next, we need to determine the total mass of the wine. Let's assume we have a 750 ml bottle of wine.

Total mass of wine = Volume of wine x Density of wine
= 750 ml x 1 g/cm3
= 750 g

Now that we have the mass of ethanol (0.131 g) and the total mass of the wine (750 g), we can calculate the mass percent:

Mass percent of ethanol = (Mass of ethanol / Total mass of wine) x 100
= (0.131 g / 750 g) x 100
≈ 0.0175 x 100
≈ 1.75%

Therefore, the concentration of ethanol in wine in terms of mass percent is approximately 1.75%.

Now, let's calculate the molality of ethanol in wine.

Molality is defined as the number of moles of solute (ethanol) per kilogram of solvent (water in this case). To calculate molality, we need to know the molar mass of ethanol and the mass of water (since wine is mostly water).

The molar mass of ethanol (C2H5OH) is:
2 carbon atoms (2 x 12.01 g/mol) + 6 hydrogen atoms (6 x 1.008 g/mol) + 1 oxygen atom (1 x 16.00 g/mol) + 1 hydrogen atom (1 x 1.008 g/mol) = 46.07 g/mol

Now, let's calculate the moles of ethanol:
moles of ethanol = mass of ethanol / molar mass of ethanol
= 0.131 g / 46.07 g/mol
≈ 0.00285 mol

The mass of water can be calculated by subtracting the mass of ethanol from the total mass of the wine:

mass of water = total mass of wine - mass of ethanol
= 750 g - 0.131 g
≈ 749.869 g

Finally, we can calculate the molality:

Molality of ethanol = moles of ethanol / mass of water (in kg)
= 0.00285 mol / (749.869 g / 1000)
≈ 0.00380 mol/kg

Therefore, the concentration of ethanol in wine in terms of molality is approximately 0.0038 mol/kg.