Question

how to prepare 100mL sodium hydroxide solution with a pH 10.00 the stock solution in lab provided is 19 M NaOH 2000.0 mL

i have to report the stock solution concentration that i started with

I have to report the concentration of the sodium hydroxide solution in scientific nota.

and what glassware is best to use to prepare it in

Answer 1

Provided: 19 M NaOH 2000.0 mL NaOH stock solution.

Needs to  prepare 100 mL sodium hydroxide solution with a pH 10.00 from the stock solution.

Now, pH + pOH = 14.00

pOH = 14.00 - pH = 14.00 - 10.00 = 4.00

Now pOH = -log[OH^-]

[OH^-] = 10^-pOH = 10^-4.00 = 1.0 10^-4 M

Therefore concentration of OH^- is the 100 mL NaOH solution of pH 10 = 1.0 10^-4 M

Now NaOH is a strong base. So it dissociates completely in solution. So concentration of OH^- = concentration of NaOH.

Now initial concentration of NaOH solution (S1) = 19.0 M

Final concentration of NaOH solution (S2) = 1.0 10^-4 M

Final Volume of NaOH solution (V2) = 100 mL

What is the volume of 19.0 M NaOH (V1) required to prepare solution with pH 10?

Now V1S1 = V2S2

or, V1 = V2S2/S1 = (100 mL 1.0 10^-4 M)/19.0 M = 5.26 10^-4 mL = 0.53 microliter.

Therefore to prepare 100 mL sodium hydroxide solution with a pH 10.00, we need to take 0.53 microliter. of stock 19.0 M NaOH solution and dilute it to 100 mL by distilled water.

Since the volume of stock NaOH solution required is very small, we need to choose a one microliter syringe to take out the stock solution accurately. Now to prepare this solution, a 100 mL volumetric flask along with the one microliter syringe is required. The 0.53 microliter of stock 19.0 M NaOH solution first needs to be taken out by the microliter syringe and put it in to the 100 mL volumetric flask. The flask then needs to be filled up by distilled water up to the mark. Solution of desired concentration is prepared.