Question

What will be the mole fraction of Ethanol (Molar mass = 46 g) in water in a solution containing 20% alcohol by mass?

Answer 1

Answer:

the answer of this question is 154

Answer 2

Answer:

The mole fraction of Ethanol in water in a solution containing 20% alcohol by mass is 0.09.

Explanation:

The mole fraction of ethanol in water will be calculated as,

$\mathrm{x=\frac{n_2}{n_1} }$             (1)

Where,

x=mole fraction of solute

n₂=number of moles of solute

n₁=number of moles of solvent

And the number of moles of a substance is calculated as,

$\mathrm{n=\frac{m}{M} }$               (2)

n=number of moles

m=given mass of the substance

M=molecular mass of the given substance

From the question, we can interpret that 20 grams of ethanol is dissolved in 80 grams of water. Now, let's calculate the number of moles of solute and solvent one by one.

Number of moles of solvent

Upon entering the necessary values into equation (2), we obtain;

$\mathrm{n_1=\frac{80}{18} }$

$\mathrm{n_1=4.45 }$              (3)

Number of moles of solute

Upon entering the necessary values into equation (2), we obtain;

$\mathrm{n_2=\frac{20}{46} }$

$\mathrm{n_2=0.434 }$             (4)

Substituting the value of "n₁" and "n₂" in equation (1) we get;

$\mathrm{x=\frac{0.434}{4.45} }$

$\mathrm{x=0.09}$

So, the mole fraction of Ethanol in water in a solution containing 20% alcohol by mass is 0.09.

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