What is the molarity of a solution prepared from 25.0 grams of methanol (CH3OH, density = 0.792 g/mL) with 100.0 milliliters of ethanol (CH3CH2OH)? Assume the volumes are additive.

Molarity = 7.8 M

Explanation:

Given data:

Mass of solute = 25.0 g

Volume of solution = 100.0 mL (100/1000 = 0.1 L)

Molarity of solution = ?

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

First of all we will calculate the number of moles of solute:

Number of moles = mass/molar mass

Number of moles  = 25.0 g/ 32.04 g/mol

Number of moles = 0.78 mol

Now we will put the values in formula.

Molarity = 0.78 mol / 0.1 L

Molarity = 7.8 mol/L

Molarity = 7.8 M