Question

You will be preparing 100 mL of a NaCl(aq) solution using a volumetric flask. a. Determine the mass of NaCl you need to prepare a 0.5 M aqueous solution. b. Determine the mass of NaCl you need to prepare a 2 M aqueous solution. (then): Using the numbers you calculated above, explain how you would prepare 100 mL of a NaCl solution of 0.5-2 M concentration.?

Answer 1

a. To prepare a 100 ml of 0.5 M NaCl (aq) solution

molarity = moles/L

moles = g/molar mass

Thus,

garms of NaCl required = 0.5 mol/L x 0.1 L x 58.44 g/mol = 2.92 g

b. To prepare a 100 ml of 2.0 M NaCl (aq) solution

molarity = moles/L

moles = g/molar mass

Thus,

garms of NaCl required = 2.0 mol/L x 0.1 L x 58.44 g/mol = 11.69 g

c. 100 ml of 0.5 M solution starting with 2 M NaCl solution

M1V1 = M2V2

Volume of 2 M NaCl solution required (V1) = 0.5 M x 100 ml/2 M = 25ml

So taken 25 ml of 2 M solution and dilute with 75 ml of water to make 100 ml solution