Calculating 100ml with a mole vs mole ratio

[miniradman]

Homework Statement

I have pure ethanol and water. When mixed, the total volume is not the sum of the individual volumes (its a little bit less). A wikipedia graph has shown that a 0.4mol ethanol to 0.6mol to water mixture is ideal to get the most contraction. (http://upload.wikimedia.org/wikipedia/commons/4/45/Excess_Volume_Mixture_of_Ethanol_and_Water.png)

How do I calculate how much ethanol and water to add if I needed to get 100ml of solution with the mole ratio is 0.4 ethanol to 0.6 water.

The Attempt at a Solution

I honestly don't know what to do, I just need hints or something because trying to get my heard around this concept in making my head hurt

Thanks, guys

 

[nate808]

!



To calculate the amount of ethanol and water needed for a 0.4:0.6 mole ratio in a 100ml solution, you can use the following formula:

V1 = (n1/n2) x V2

Where V1 is the volume of ethanol needed, n1 is the number of moles of ethanol, V2 is the total volume of the solution (100ml in this case), and n2 is the total number of moles (0.4 + 0.6 = 1).

To calculate the number of moles of ethanol (n1), you can use the formula:

n1 = (V1 x C1)/1000

Where C1 is the concentration of ethanol in the solution (0.4 mol/L in this case).

Substituting the values in the first formula, we get:

V1 = (0.4/1) x 100ml = 40ml

To calculate the volume of water needed, we can use the same formula, with the concentration of water (0.6 mol/L) and the total number of moles (1):

V2 = (n1/n2) x V2 = (0.6/1) x 100ml = 60ml

Therefore, to get a 0.4:0.6 mole ratio in a 100ml solution, you will need to mix 40ml of ethanol and 60ml of water.

I hope this helps! Let me know if you have any further questions.