Find a) molar fraction, b) concentration in mol / and c) concentration in mol / kg of an aqueous solution with 25% alcohol: the molar mass of alcohol is 46g / mol and the density is 0.8g / cm3​

Explanation:

Answer

( 58.3 mL )(

0.789 g

1 mL

)(

1 mole

46 g

) = 1 mole C2H5OH

( 500 mL H2O )(

1 g

1 mL

)(

1 mole

18 g

) = 27.8 mole H2O

The total moles = 1 mole C2H5OH + 27.8 mole H2O = 28.8 moles

The mole fraction =

moles C2H5OH

total moles

=

1 mole C2H5OH

28.8 total moles

= 0.035

The mole percent would be 3.5%.

What is the weight fraction?

Answer

( 58.3 mL )(

0.789 g

1 mL

) = 46 g C2H5OH

( 500 mL H2O )(

1 g

1 mL

) = 500 g H2O

The total mass = 46 g C2H5OH + 500 g H2O = 546 g

The mass fraction =

mass C2H5OH

total mass

=

46 g C2H5OH

546 total grams

= 0.084

The mass percent would be 8.4%.

What is the molarity?

Answer

The molarity =

moles C2H5OH

L of solution

=

1 mole C2H5OH

.5583 L

= 1.79 M

What is the molality?

Answer

The molality =

moles C2H5OH

kg of solvent

=

1 mole C2H5OH

0.5 kg H2O

= 2

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