Question

calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.40​

Answer 1

2.1 M

Given:

Mass Of Ethanol = 0.04 mole

Moles of Water = 1 - 0.04 = 0.96 mol

Mass Of Water:

= 0.96 * 18

= 17.3 grams

Mass Of Ethanol:

= 0.04 * 46

= 1.84 grams

Total Mass Of The Solution:

= 17.3 + 1.84

= 19.14 grams

Density of water = 1 g/ml assumed

Density = Mass / Volume

=> Volume = Mass / Density

Substituting the values in this formula:

19.1 / 1 = 19.1 mL

Converting to liters:

= 19.1 / 1000  

=  0.0191 Liters

Molarity = Mole / Density

Therefore, Molarity:

= 0.04/0.0191

= 2.1 M