You are asked to make 500 mL of a 0.250 M sodium chloride (NaCl) solution. How many moles of NaCl would you need? How many grams of NaCl would you need?

Answer 1

First, 500 mL = 0.5 liters

Molarity is moles/liter so 0.250 M = (x moles)/(0.5 liters) or x = 0.25(0.5) = 0.125 moles = 0.13 moles

NaCl is made of Na + Cl

Na = 22.99 grams/mole

Cl = 35.45 grams/mole

So NaCl = 22.99 + 35.45 = 58.44 g/mol

Since there are 0.125 moles, then 58.44 x 0.125 = 7.3 grams

There is actually only 1 sig fig in the givens so in reality, both answers SHOULD be rounded to 1 sig fig