Question

8. Calculate the molarity of solution of ethanol in water in which the mole fraction of ethanol is 0.25 (assume the density of water to be one).​

Answer 1

Answer :-

Molarity of the solution is 10 M .

Explanation :-

We have :-

→ Mole fraction of ethanol = 0.25

→ Molar mass of ethanol = 46 g/mol

→ Molar mass of water = 18 g/mol

______________________________

We are given with 0.25 moles of ethanol, so the number of moles of water :-

= 1 - 0.25

= 0.75 moles

Mass of ethanol :-

= No of moles × Molar mass

= 0.25 × 46

= 11.5 g

Mass of water :-

= No of moles × Molar mass

= 0.75 × 18

= 13.5 g

Mass of the solution :-

= (13.5 + 11.5)g

= 25 g

Volume of the solution :-

= Mass/Density

= 25/1

= 25 mL

= 0.025 L

______________________________

Molarity of the solution :-

= Moles of solute/Liters of solution

= 0.25/0.025

= 250/25

= 10 M

Answer 2

Answer:

$\huge \fbox{\huge \color{pink} \fcolorbox{red}{cyan}{GiveN™}}$

• That the Mole Fraction of Ethanol Is 0.25

• the points to be known is

1. Molar Mass Of Ethanol is 46 g / mol
2. Molar Mass Of Water is 18 g / mol

No. of Moles of Water = 1-0.25

• =0.75 moles

(since the no. of moles of ethanol is 0.25)

-----» Mass Of Ethanol Is

No. of moles × Molar Mass = [0.25×46]

• 11.5 grams

-----» Mass Of Water is

No. of moles × Molar Mass =[0.75×18]

• 13.5 grams

Now The Total Mass Of The Given Solution is

• Mass of Ethanol + Mass of Water

≠=====>11.5+13.5 = 25 Grams

Volume of the following solution is

• Volume = Mass / Density

here the density of water is 1. (given)

• Mass= 25 grams
• Density =1

≠======>25/1

• 25ml
• 25 ml = 0.025L

Now, The Molarity Of The Following Solution is

M=n/v

[Where M = molar concentration.

n = moles of solute.

v = liters of solution.]

M=0.25/0.025

• ≠=====>250/25

$\huge{ \pink{ \tt{-» Molarity \: \: is \: \: equal \: \: To \: \: \green{\fbox{10}}}}}$

Explanation:

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