soma
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how to get pH of colored solution
I want to get the pH of a darkly colored solution. Don't want to use a meter cause it would clog the electrode. It's too dark to get a reading from pH
papers.
Help appreciated.
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Etaoin Shrdlu
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What's in it?
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confused
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dilute it slightly before using a pH meter?
it shouldn't affect the pH that much
then wash the electrode immediately after use to prevent it from getting clogged up
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HgDinis25
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Do you need only an aproximation or do you need an exact value?
A very crazy-noob method would be to add some Sodium Carbonate. If CO2 is released then you have a pH lower than 7. If nothing happens try Sodium
Bicarbonate. If CO2 is released then you have a pH higher than 7. If nothing happens in both cases, then you have a pH of 7. Of course this can be
affected in an enormous variety of ways, like the solution reacting with the NaCO3 or the NaHCO3 but not because of the pH.
You could also take a known volume of your solution (small) and dilute it with a known volume of water until it gets clear enough to get a readning.
Then take the pH. Calculate the concentration of H3O in that soltuion. From there you can go to the amount of H3O in the sample before diluting and
then you can calculate the concentration. If you don't kno how to do the math just give the values and I'll help you out.
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DraconicAcid
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Quote: Originally posted by HgDinis25  | Do you need only an aproximation or do you need an exact value?
A very crazy-noob method would be to add some Sodium Carbonate. If CO2 is released then you have a pH lower than 7. If nothing happens try Sodium
Bicarbonate. If CO2 is released then you have a pH higher than 7. If nothing happens in both cases, then you have a pH of 7. |
Why do you think that a basic solution will react with sodium bicarbonate to give off carbon dioxide? Hydroxide reacts with the bicarbonate ion to
give carbonate ion and water.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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HgDinis25
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| Quote: Originally posted by DraconicAcid | | Quote: Originally posted by HgDinis25 | Do you need only an aproximation or do you need an exact value?
A very crazy-noob method would be to add some Sodium Carbonate. If CO2 is released then you have a pH lower than 7. If nothing happens try Sodium
Bicarbonate. If CO2 is released then you have a pH higher than 7. If nothing happens in both cases, then you have a pH of 7. |
Why do you think that a basic solution will react with sodium bicarbonate to give off carbon dioxide? Hydroxide reacts with the bicarbonate ion to
give carbonate ion and water. |
Yes you're right. I stand corrected. Bases will just form the carbonate and no CO2 is evolved.
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Brain&Force
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Carbonate and bicarbonate exist in equlibrium. Bicarbonate can be protonated, as can carbonate, to form carbonic acid which immediately decomposes
into carbon dioxide. Bicarbonate is deprotonated in basic conditions, with no discernible reaction.
At the end of the day, simulating atoms doesn't beat working with the real things...
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