Question

Calculate the molarity of 29.0g of ethanol (C2H5OH) in 545 mL of solution.

Answer 1

There are a number of ways to express concentration of a solution. This includes molarity. Molarity is expressed as the number of moles of solute per volume of the solution. Molarity of the solution given is calculated as follows:

M = (29.0 g ethanol) (1 mol / 46.07 g) / 545mL (1L / 1000mL)
M = 1.16 mol / L 

Answer 2

Molar mass ethanol:

C2H5OH = 12 x 2+ 1 x 5 + 16  + 1 =  46.0 g/mol

volume = 545 mL in liters: 545 / 1000 => 0.545 L

number of moles:

29.0 / 46.0 => 0.6304 moles

M = n / V

M = 0.6304 / 0.545

M = 1.156 mol/L

hope this helps!