A mass of 100.0 g of solute is dissolved in water so that 850. mL of a 0.7500 M solution has been prepared. What is the molar mass of the solute?

156.86 g / mol

Explanation:

We start from the molarity law

Cm = n / V

n = w / M

then

Cm = (w / M) / V

Cm = w / (M * V)

where:

Cm is the molarity

n number of moles

w a mass of the solute

M is the molar mass of the solute (which is needed)

V the volume of the solution in liters

Then the M can be calculated as following:

M = w / (Cm * V)

M = 100 / (0.75 * 0.85) = 156.86 g / mol