Question

You wish to prepare 50.00 mL of 0.0600 M NH₃ from concentrated ammonia (15.28 M) by serial dilution using a 50 mL volumetric flasks, a 1.00 mL volumetric pipet, and a 10.00 mL graduated pipet.

For the first dilution in the series, 1 mL of concentrated ammonia is added to a 50.00 volumetric flask and then filled to the line. The solution is mixed thoroughly, poured into a beaker, and then used to make the second solution in the series. What volume of the first solution should be used to make the second solution, 50.00 mL of 0.0600 M NH₃ solution

Answer 1

Concentration of ammonia solution made in first dilution(M2) can be calculated using following formula:

M1V1 = M2V2

Where, M1 = molarity of concentrated ammonia solution. M2 = molarity of solution obtained after first dilution. V1 = volume of concentrated ammonia solution. V2 = volume of solution obtained after first dilution.

Therefore, M2 = M1V1 / V2

M2 = (15.28 M x 1 mL) / 50 mL

M2 = 0.3056 M

Volume of first solution required to make 50.00mL of 0.0600 M second solution can be calculated using following formula:

M2V2 = M3V3

Where,

M2 = molarity of solution obtained after first dilution. M3 = molarity of solution obtained after first dilution. V2 = volume of solution obtained after first dilution. V3 = volume of solution obtained after second dilution.

Therefore, V2 = M3V3 / M2

V2 = (0.0600 M x 50.00 mL) / 0.3056M

V2 = 9.817 mL

Thus, Volume of first solution required to make 50.00mL of 0.0600 M second solution is 9.817 mL