Question

Suppose you need to prepare 136.9 mL of a 0.315 M aqueous solution of NaCl.

What mass, in grams, of NaCl do you need to use to make the solution?

Answer 1

Answer:

2.52 g NaCl

Explanation:

(Step 1)

To find the mass, you first need to find the moles NaCl. This value can be found using the molarity ratio:

Molarity = moles / volume (L)

After you convert mL to L, you can plug the given values into the equation and simplify to find moles.

136.9 mL / 1,000 = 0.1369 L

Molarity = moles / volume

0.315 M = moles / 0.1369 L

0.0431 = moles

(Step 2)

Now, you can use the molar mass to convert moles to grams.

Molar Mass (NaCl): 22.990 g/mol + 35.453 g/mol

Molar Mass (NaCl): 58.443 g/mol

0.0431 moles NaCl           58.443 g
------------------------------  x  -------------------  =  2.52 g NaCl
                                            1 mole