# Chemistry

posted by .

A solution is made by mixing 42.0 mL of ethanol, C2H6O, and 58.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 C in torr?
Values at 20C
ethanol density: 0.789 g/mL & vapor pressure (torr): 43.9 torr
water: denisty: 0.998 g/mL & 17.5 torr

Any steps would be GREATLY appreciated!

• Chemistry -

Calculate moles H2O.
Calculate moles EtOH.
Calculate XH2O
Calculate XEtOH.
Calculate pH2O
Calculate pEtOH.
Total P = pH2O + pEtOH

• Chemistry -

Hi Dr Bob, is this right so far?
mass h2o = (d)(v) = (0.998 g/mL)(58 mL) = 57.884 g
57.884 g H2O/18g H2O = 3.2157 mol H2O
mass ethanol = (0.789 g/mL)(42 mL) = 33.138 g
33.138 g C2H6O/46.0687 g C2H6O = 0.719 mol C2H6O

molality (m) = 0.71937 mol C2H6O/0.057884 kg H2O = 12.43 m

xH2O = 12.45/(12.43+3.2157) = 0.794
xEthanol = 12.43/(12.43 + 0.719) = 0.91
?

• Chemistry -

Hi Dr Bob, is this right so far?
mass h2o = (d)(v) = (0.998 g/mL)(58 mL) = 57.884 g
57.884 g H2O/18g H2O = 3.2157 mol H2O
mass ethanol = (0.789 g/mL)(42 mL) = 33.138 g
33.138 g C2H6O/46.0687 g C2H6O = 0.719 mol C2H6O

You are ok to here with moles.
You don't need molality. You want mole fraction. mole fraction EtOH = XEtOH = moles EtOH/total moles. mole fraction H2O = XH2O = moles H2O/total moles
Then pH2O = XH2O*PoH2O and
pEtOH = XEtOH*PoEtOH.
Total P = pH2O + pEtOH.

molality (m) = 0.71937 mol C2H6O/0.057884 kg H2O = 12.43 m

xH2O = 12.45/(12.43+3.2157) = 0.794
xEthanol = 12.43/(12.43 + 0.719) = 0.91
?

• Chemistry -

i got it! thanks Dr Bob

## Similar Questions

1. ### chemistry

What is the mass/vol % ethanol in an ethanol-water solution with density of 0.875 g/ml and containing 65.0% ethanol by volume?
2. ### CHEMISTRY

At 63.5 degreesC, the vapour pressure of H2O is 23.3kPa and that of ethanol is 53.3kPa. A solution is made by mixing egual masses of H2O and C2H5OH. a. what is the mole fraction of ethanol in the solution?
3. ### chem

A 4.1 L sealed bottle containing 0.25 g of liquid ethanol, C2H6O, is placed in a refrigerator and reaches equilibrium with its vapor at -11°C. The vapor pressure of ethanol is 10 torr at -2.3°C and 40 torr at 19°C. (a) What mass …
4. ### chemistry

the vapor pressure of ethanol at 20c is 44 mmHg and the vapor pressure of methanol at the same temperature is 94mmHg. A mixture of 30.0 g of methanol and 45.0 g of ethanol is prepared (and can be assumed to behave as an ideal solution). …
5. ### Chemistry

A solution is made by mixing 30.0 mL of ethanol, C2H6O, and 70.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 °C?
6. ### Chem 2

A solution is made by mixing 47.0 mL of ethanol, C2H6O, and 53.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 °C?
7. ### Chemistry II

A solution is made by mixing 38.0 mL of ethanol, C2H6O, and 62.0 mL of water. Assuming ideal behavior, what is the vapor pressure of the solution at 20 °C?
8. ### Chemistry

A solution is made by mixing 37.0 mL of ethanol, C2H6O, and 63.0 mL of water.?
9. ### chemistry

What is the percent by volume (% v/v) of a solution made by mixing 12 ml of ethanol (C2H5OH) with 48 ml of water?
10. ### chemistry

a solution is made by mixing 38.0 ml of ethanol C2H6O, 62.0mL of water. assuming ideal behavior, what is the vapor pressure of the solution at 20 C

More Similar Questions

Post a New Question