Molarity of a solution of ethanol in water

[powergirl]

Calculate the molarity of a solution of ethanol in water,in which the mole fraction of ethanol is 0.040.
Can anyone help me to solve this problem?

 

[mark-ashleigh]

i think

Then the mole fraction of water is 0.96...so the solution is 96% water and 4%Ethanol...this shoule help you going if you were unsure what the fraction was.

Molarity= Moles of Solute / litres of solution

Mole fraction (Ethanol) = Moles of Ethanol/ Moles of Ethanol + Water

So do you know how many Litres or are you just going to assume?

So if we use a basis of 100 moles...96 moles are water and 4 moles are ethanol and assume 150 litres

therefore

molarity = 4 moles /150 litres = 0.0266

 

[powergirl]

Thanks for helping me...:)

 

[Borek]

Then the mole fraction of water is 0.96...so the solution is 96% water and 4%Ethanol...

Only in terms of moles, stating it this way may sound like you are suggesting this solution is just 4% w/w ethanol - which is not true (it is 9.6% w/w).

It will be better said that such solution contains 4 moles of ethanol per every 96 moles of water.

 

[mark-ashleigh]

No..i said mole fraction not w/w

 

[mark-ashleigh]

I know what you mean though...