An aqueous solution is 1.33 molality in method determine the amount fraction of methenal and water

Answer 1

Methanal is also formaldehyde, which has a chemical formula of HCHO (or CH2O).
Molarity is moles of solute per liter of solution. Thus we can say there are 1.33 moles of CH2O in 1 L of solution.
To get the mole fraction, we also need to get the moles of H2O. To do this, we get the volume of 1.33 mol CH2O from the moles by multiplying moles by its molar mass, and then dividing it by its density. From references, at normal conditions, the density of CH2O = 0.8153 g/mL.
molar mass of CH2O = 12 + 2 + 16 = 30 g/mol
V, CH2O = 1.33 mol (30 g/mol) / 0.8153 g/mL
V, CH2O = 48.939 mL CH2O

V, H2O = 1000 mL - 48.939 mL
V, H2O = 951.061 mL
Then we get the moles of H2O from the volume by multiplying it by the density and then dividing it by the molar mass. From references, at normal conditions, density of H2O = 1 g/mL
molar mass of H2O = 2 + 16 = 18 g/mol
n, H2O = (951.061 mL)(1 g/mL) / 18 g/mol
n, H2O = 52.837 mol H2O

We can therefore get the mole fractions:
x, CH2O = 1.33 / (1.33 + 52.837)
x, CH2O = 0.0246

x, H2O = 1 - 0.0246
x, H2O = 0.975

Hope this helps~ :)

Answer 2

*shocks it's in MOLALITY. @_@ Please disregard the above post!

Molality is moles of solute per kilogram solvent. Thus we can say there are 1.33 moles of CH2O in 1000 g of H2O.

To get the moles of H2O, we divide the mass (1000 grams H2O) by its molar mass.
molar mass of H2O = 2 + 16 = 18 g/mol
n, H2O = (1000 g) / 18 g/mol
n, H2O = 55.56 mol H2O

We can therefore get the mole fractions:
x, CH2O = 1.33 / (1.33 + 55.56)
x, CH2O = 0.0238

x, H2O = 1 - 0.0238
x, H2O = 0.9762

Sorry about that. lol the solution was way shorter compared to the previous.
By the way, I'm not sure if you really meant "methanal" or "methanol" (CH3OH). But either way, the value of the mole fractions are the same. (But of course, if it's molarity, they won't be the same)

Hope this helps~ ;)