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Why does a pink color appear and then disappear quickly at the point where the NaOH solution comes in contact with the solution in the flask?
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+ Sodium hydroxide
+ Chemistry
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Michael Muirhead
Why does a pink color appear and then disappear quickly at the point where the NaOH solution comes in contact with the solution in the flask?
Color is color, it has nothing to do with toxicity, do you think a dark red wines is toxic because it is dark? I can give you a very toxic solution which is perfectly clear, could be fullof lead, cadmium, mercury etc.
The only time you could make such an affirmation is that a chemist told you that in the light solution, there is something toxic, the if you have the same solution but just more concentrated, it would indeed be more colored and now youcould say the more intense is more dangerous.
If you still believe colored solution are dangerous, then do not drink red wine, no coke, root beer etc.
Color is color, it has nothing to do with toxicity, do you think a dark red wines is toxic because it is dark? I can give you a very toxic solution which is perfectly clear, could be fullof lead, cadmium, mercury etc.
The only time you could make such an affirmation is that a chemist told you that in the light solution, there is something toxic, the if you have the same solution but just more concentrated, it would indeed be more colored and now youcould say the more intense is more dangerous.
If you still believe colored solution are dangerous, then do not drink red wine, no coke, root beer etc.
You are describing an acid-base titration: adding dilute NaOH solution (base) dropwise to a *stirred* flask of a dilute HCl water solution (acid). The pink color comes from the 2 drops of phenolphthalein (Phth) indicator solution added at the beginning. The acid-base reaction is invisible without the addition of the Phth. Early in the addition of the NaOH the pink color might not be visible. When you get to about the half-way point, then the pink color you are asking about becomes visible.
When a drop of NaOH solution hits the surface of the stirring HCl, the concentration of NaOH at the point of impact is high; the NaOH hasn’t yet dispersed sufficiently to dilute it below the pH value of the Phth indicator. As the solution stirs, this brief pink flash disperses since the amount of HCl in the solution still exceeds the amount of NaOH added so far. As you near the endpoint of the titration (where the number of moles of acid = number of moles of base) the pink flash becomes more persistent. At some point the pink color will be so persistent that several seconds of stirring are needed to return the solution in the flask to colorless after each drop of base. Eventually you will add “one more drop” that will make the entire solution in the flask become pink and remain pink for more than 30 seconds even while stirring. This is a successful titration endpoint. Read your burette(s) and record the numbers in your notebook.
If you let this pink endpoint solution continue to stir for a while (without your adding anything) it will very slowly (minutes) become colorless again. This is due to the surface of the stirred liquid being in contact with the atmosphere in the room. What might be in the earth’s atmosphere that would react with a solution with a slight excess of base (about pH 9) and return it to “the acid side”? A good question.
You are describing an acid-base titration: adding dilute NaOH solution (base) dropwise to a *stirred* flask of a dilute HCl water solution (acid). The pink color comes from the 2 drops of phenolphthalein (Phth) indicator solution added at the beginning. The acid-base reaction is invisible without the addition of the Phth. Early in the addition of the NaOH the pink color might not be visible. When you get to about the half-way point, then the pink color you are asking about becomes visible.
When a drop of NaOH solution hits the surface of the stirring HCl, the concentration of NaOH at the point of impact is high; the NaOH hasn’t yet dispersed sufficiently to dilute it below the pH value of the Phth indicator. As the solution stirs, this brief pink flash disperses since the amount of HCl in the solution still exceeds the amount of NaOH added so far. As you near the endpoint of the titration (where the number of moles of acid = number of moles of base) the pink flash becomes more persistent. At some point the pink color will be so persistent that several seconds of stirring are needed to return the solution in the flask to colorless after each drop of base. Eventually you will add “one more drop” that will make the entire solution in the flask become pink and remain pink for more than 30 seconds even while stirring. This is a successful titration endpoint. Read your burette(s) and record the numbers in your notebook.
If you let this pink endpoint solution continue to stir for a while (without your adding anything) it will very slowly (minutes) become colorless again. This is due to the surface of the stirred liquid being in contact with the atmosphere in the room. What might be in the earth’s atmosphere that would react with a solution with a slight excess of base (about pH 9) and return it to “the acid side”? A good question.
Color is color, it has nothing to do with toxicity, do you think a dark red wines is toxic because it is dark? I can give you a very toxic solution which is perfectly clear, could be fullof lead, cadmium, mercury etc.
The only time you could make such an affirmation is that a chemist told you that in the light solution, there is something toxic, the if you have the same solution but just more concentrated, it would indeed be more colored and now youcould say the more intense is more dangerous.
If you still believe colored solution are dangerous, then do not drink red wine, no coke, root beer etc.
Color is color, it has nothing to do with toxicity, do you think a dark red wines is toxic because it is dark? I can give you a very toxic solution which is perfectly clear, could be fullof lead, cadmium, mercury etc.
The only time you could make such an affirmation is that a chemist told you that in the light solution, there is something toxic, the if you have the same solution but just more concentrated, it would indeed be more colored and now youcould say the more intense is more dangerous.
If you still believe colored solution are dangerous, then do not drink red wine, no coke, root beer etc.
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You are describing an acid-base titration: adding dilute NaOH solution (base) dropwise to a *stirred* flask of a dilute HCl water solution (acid). The pink color comes from the 2 drops of phenolphthalein (Phth) indicator solution added at the beginning. The acid-base reaction is invisible without the addition of the Phth. Early in the addition of the NaOH the pink color might not be visible. When you get to about the half-way point, then the pink color you are asking about becomes visible.
When a drop of NaOH solution hits the surface of the stirring HCl, the concentration of NaOH at the point of impact is high; the NaOH hasn’t yet dispersed sufficiently to dilute it below the pH value of the Phth indicator. As the solution stirs, this brief pink flash disperses since the amount of HCl in the solution still exceeds the amount of NaOH added so far. As you near the endpoint of the titration (where the number of moles of acid = number of moles of base) the pink flash becomes more persistent. At some point the pink color will be so persistent that several seconds of stirring are needed to return the solution in the flask to colorless after each drop of base. Eventually you will add “one more drop” that will make the entire solution in the flask become pink and remain pink for more than 30 seconds even while stirring. This is a successful titration endpoint. Read your burette(s) and record the numbers in your notebook.
If you let this pink endpoint solution continue to stir for a while (without your adding anything) it will very slowly (minutes) become colorless again. This is due to the surface of the stirred liquid being in contact with the atmosphere in the room. What might be in the earth’s atmosphere that would react with a solution with a slight excess of base (about pH 9) and return it to “the acid side”? A good question.
Thanks for Listening
You are describing an acid-base titration: adding dilute NaOH solution (base) dropwise to a *stirred* flask of a dilute HCl water solution (acid). The pink color comes from the 2 drops of phenolphthalein (Phth) indicator solution added at the beginning. The acid-base reaction is invisible without the addition of the Phth. Early in the addition of the NaOH the pink color might not be visible. When you get to about the half-way point, then the pink color you are asking about becomes visible.
When a drop of NaOH solution hits the surface of the stirring HCl, the concentration of NaOH at the point of impact is high; the NaOH hasn’t yet dispersed sufficiently to dilute it below the pH value of the Phth indicator. As the solution stirs, this brief pink flash disperses since the amount of HCl in the solution still exceeds the amount of NaOH added so far. As you near the endpoint of the titration (where the number of moles of acid = number of moles of base) the pink flash becomes more persistent. At some point the pink color will be so persistent that several seconds of stirring are needed to return the solution in the flask to colorless after each drop of base. Eventually you will add “one more drop” that will make the entire solution in the flask become pink and remain pink for more than 30 seconds even while stirring. This is a successful titration endpoint. Read your burette(s) and record the numbers in your notebook.
If you let this pink endpoint solution continue to stir for a while (without your adding anything) it will very slowly (minutes) become colorless again. This is due to the surface of the stirred liquid being in contact with the atmosphere in the room. What might be in the earth’s atmosphere that would react with a solution with a slight excess of base (about pH 9) and return it to “the acid side”? A good question.
Thanks for Listening
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