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Postby Maria1E » Fri Dec 01, 2017 5:25 pm

A student added solid Na2O to a 200. mL volumetric flask, which was then filled with water, resulting in 200. mL of NaOH solution. 5.00 mL of the solution was then transferred to another volumetric flask and diluted to 500 mL. The pH of the diluted solution is 13.25.

I figured out the answer to part a (which asked for the concentration of hydroxide ion in the diluted solution). = .18 M

b) What is the concentration of the hydroxide ion in the original solution?

I understand that I am supposed to convert the .18 M to a molarity of the original solution, but I'm not sure what to multiply/divide .18 by. Thank you!

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Re: 12.33

Postby Chem_Mod » Sat Dec 02, 2017 4:34 pm

You would multiply by the dilution factor. You took 5 mL of the concentrated solution and diluted it to 500 mL. Therefore, you diluted it by 100 times, and your original solution was 18 M.

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