Molar concentration of HCO3-

Anti-Pjerrot

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Apr 5, 2006
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What is the molar concentration of HCO3- equal to 4kH?

Ive looked at some different explainations, but ive found no clear answer, and it confuses me...

There was a scheme with recalculations of kH somewhere...
 

Tom Barr

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4 KH = 71.44 ppm or mg/L.

HCO3 per mole = 1+12+16*3 = ~61 grams per mole.

So about 71.44/61 = a little over 1

Regards,
Tom Barr
 

Anti-Pjerrot

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4 kH = 0,0744g/L (You forgot to calculate mg to g)

So 4kH equals 0,001171147M of NaHCO3, and if i wanted to test my kH 4 solution...

I would titer my kH 4 solution with a 0,1000M HCl, and i should use 11,71mL HCl/L right?
 

Tom Barr

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Well, there abouts, I do not think you need to be so accurate here.
Most use sodium carbonate for KH solutions.

Regards,
Tom Barr
 

Anti-Pjerrot

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But if i wanted to make a 4,00 kH solution, i need som accuracy.

Im making a batch with 0,2495g of dried NaHCO3 (200ºC for 45min) dissolved in 2,0 L MQ water.

That should give me roughly a kH 4 solution.

Then i would just titer it with HCl to find the exact concentration, and adjust it with more MQ water/NaHCO3.

Or is there an easier method to make kH 4,00 without a standard solution.

I got all the lab equipment possible (well almost)

If you got an easier method im all ears. :)
 

Tom Barr

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Using sodium carbonate, not bicarbonate. Less issues with drying/heaqting driving off some of ref powder.

And of course, checking your ahem, units from mg to grams.
I might make a mistake:)

You can also buy pre made ref samples.

Regards,
Tom Barr