Question

How many grams would be needed to prepare 389 mL of a 0.77 M solution of magnesium hydroxide? Explain your process and how you got your answer.

Answer 1

In order to find the grams needed to prepare this solution, we first need to find the number of moles present in this solution, we will do that by using the Molarity formula:

M = n/V

where:

M = concentration

n = number of moles

V = volume in liters

0.77 = n/0.389

n = 0.299 moles of Mg(OH)2

Now using its molar mass, 58.32 g/mol, we can find the right number of grams needed:

58.32 = 1 mol

x grams = 0.299 moles

x = 17.44 grams of Mg(OH)2