Question

In Part A, you explored the relationship between molarity, the number of moles, and solution volume. However, when you prepare a solution, you are unable to directly measure the number of moles of solute. Instead, you can mass the solute and convert between the number of moles and mass using the molar mass of a substance as a conversion factor. The molar mass of a substance can be calculated based on its molecular formula; otherwise, it can be calculated from the mass and number of moles as follows:

Molar Mass = Mass solute (in g)Moles solute

In order to prepare a certain volume of solution with a desired concentration, you would need to determine the required mass of solute. What mass of MgCl2 would you need to prepare a 100. mL solution at a concentration of 0.150  M ?

Express the mass in grams to three significant figures.