chipster1234
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Alkalinity question
Dear All
I have a mixture of 8wt% KOH (solid) together with 13wt% of NaOH 48% (liquid) all in 50gms of water.
Do any of you guys know how we go about calculating the theoretical alkalinity value of the whole solution? (in percentages)???
Im NOT referring to the titration method.
please help...
[Edited on 31-5-2012 by chipster1234]
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woelen
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Your question is not clear. Tell me how you would make your solution, starting with how much water and then adding how many grams or ml of the
hydroxides. Present this step by step and maybe some of us can then help you with your computation. We do no spoonfeeding, also tell us what you
already tried and where you get stuck.
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woelen
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Thread Moved
31-5-2012 at 10:48 |
chipster1234
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Hi all
below is how i would make my formula blend.
I add:-(sequentially)
(1) 50wt% water
(2)8wt% KOH solid
(3) 13wt% NaoH 48%
then when everything is dissolved, i add
29wt% Sodium Hypochlorite 10%
Based on this formula, doing a titration to determine the alkalinity gave me an alkalinity of 18%
However, if im thinking of changing my formulations by playing around with the amount KOH and NaOH, is there any theoretical way of determining the
alkalinity before hand instead of doing titrations for every deviation. cuz that would save up a lot of time.
i really hope this helps
thanks woelen
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woelen
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You can compute the alkalinity by computing the amount of hydroxide in your solution. Based on your numbers I find 0.156 mole of NaOH and 0.143 mole
of KOH. Together this is appr. 0.3 mole of hydroxide per 100 gram of liquid.
You must multiply moles of hydroxide by 50 (molar weight of CaCO3, divided by 2) to get percentage of alkalinity. So, based on molar amount of
hydroxide I get an alkalinity of 15%.
The unknown in this computation is the sodium hypochlorite solution. This also is strongly alkaline and adds additional hydroxide. Your solution
apparently adds 1% of alkalinity for each 10% of weight.
So, computing total alkalinity can be done as follows:
compute amount of NaOH (in moles)
compute amount of KOH (in moles)
Add these two numbers to get total amount of hydroxide in moles and multply with 50.
For each percent by weight of your bleach add another 0.1% of alkalinity.
This formula assumes that you always have a total weight percentage of 100%, so if e.g. you take 10% of KOH, 30% of NaOH solution and 20% of bleach,
then you must add 40% of water.
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chipster1234
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thanks a lot for your help, woelen
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