# Mass of KHP needed to be neutralized by NaOH?

I have a sample with an unknown percentage of KHP (Potassium hydrogen phthalate) in it and I need to estimate the best sample size to be used in the titration of solid KHP in water being titrated with NaOH.

The sample size should be found using the following assumptions. Assume your NaOH solution is 0.050M; assume the sample is 55% KHP; assume the

volume of NaOH required is 35 mL.

So how do I calculate the sample size of the unknown KHP that would be consistent with these assumptions?

Thanks!

spock

Wed, 2011-04-20 22:41

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## Re: Mass of KHP needed to be neutralized by NaOH?

moles of KHP = moles of NaOH

moles of NaOH = .035L x .050mol/L

Find the mass of KHP using the molar mass.

Set up a proportion:

55 g KHP / 100g = mass of KHP from above / x

Where x is the mass that you are looking for.

sman5109

Wed, 2011-04-20 22:47

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## Re: Mass of KHP needed to be neutralized by NaOH?

So 35ml of .05M NaOH is .00175 moles then the ratio is 1:1 for the reaction with KHP, so I multiply the moles of naoh by the mass of KHP to get how much it would take to neutralize 100% KHP ( .00175mol*204.2g/mol = .3573g KHP) then because its 55% i have to increase .3573g KHP by 45% to make up the difference so, .3573g KHP * 1.45 = 0.52g KHP?

Is that right?