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At work I'm tasked with neutralizing 0.9L of 0.1M Hydrochloric acid as fast as possible. I use 40% w/v KOH solution as the base (7.13M if I calculated correctly).
Since its a stong acid with a strong base I used M1V1=M2V2 to calculate that it would take 0.126L of 7.13M KOH to neutralize 0.9L of 0.1M HCl.
In practice, however, this amount never works. I need to get the pH to 6.5-8.0 but I always drastically overshoot or undershoot the target.
Even adding the same amount to an identical sample will give different results. For example, I added 0.122L KOH for a pH of 10.1. I added 0.122 KOH to another sample for a pH of 3.7.
Can someone explain why these extreme variations exist? Should I use a more dilute base? Work wants me to just titrate everything but there's got to be a faster way...
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>>8700097
>work
This board isn't your personal tutor anon, try being less of a brainlet
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>>8700097
>Work wants me to just titrate everything
do that
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>>8700097
Repeat a lot.
HCl and NaOH are obviously garbage as far as buffers are concerned, and water isn't the best at that either. Even barely overshooting the solution is going to give you a huge jump in pH.
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"""""Work"""""
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>I'm tasked with neutralizing 0.9L of 0.1M Hydrochloric acid
>I need to get the pH to 6.5-8.0
>I use 40% w/v KOH solution
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>>8700564
well, i'm serious, titrate it once, it's gonna take you half an hour at most and extrapolate from there
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>>8700097
The extreme variation exists because what you're trying to do is eyeball a value that has to be exact. Just look at the picture you posted, a difference of a few mL of the base can cause a huge difference in the pH of the final solution. It wants you to titrate it so that the change is gradual enough that you can stop adding more base right when the pH enters the desired region.
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Are you retarded, serious question
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there's a lot of things that could be wrong, I'm assuming you're not a retard and you're using a proper burette for this. Check if you didn't fuck up the solutions, maybe when you titrated one sample and you refilled the burette you added acid instead of more base, if you're not labeling correctly it's something that could happen. Maybe the glassware wasn't properly washed and had impurities from previous runs that changes the outcome. Then again if you're at work I'm assuming you're not a student anymore and are above those sorts of errors.
I don't know Anon, maybe you just suck at Chemistry and should give up now.
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Are you retarded? One drop which is app. 0.02 mL contains even 0.15 mmol hydroxide ions. That instantly shifts pH from 7 to above 10 after neutrlizing the acid. 1 drop. Learn about pH and log scale.
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Yes you need to use a more dilute base you also need to design a process in which you quickly add most of the base before equivalence point at once then a small final portion slowly so you don't overshoot, with proper mixing of course.
7.13M is an absurdly high concentration for this purpose. I won't do the math for you, but it is fairly simple.
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