March 28, 2024, 08:59:34 PM
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91
Based on what you said, it seems obvious that the adjusting the pH with H3PO4 will increase the amount of phosphate in the buffer which has already 5mM of ammonium phosphate monobasic, so the molarity of phosphate will increase and it can't stay the same or decrease.
What is missing in this paragraph is a consideration of the volume of H3PO4.  Does that help?
92
Yes,

That's not a correct answer.


Why, what do you mean
You cut out only the Word yes
Should it be NO. For what reason?

I am assuming you answered

So the addition of phosphoric acid should affect the final concentration of phosphate buffer. right?

Neither "yes" nor "no" are correct answer.

Sad that you both attempt to guess instead of doing the math.

I think YOU are wrong, unless you can explain.
93
Yes,

That's not a correct answer.


Why, what do you mean
You cut out only the Word yes
Should it be NO. For what reason?

I am assuming you answered

So the addition of phosphoric acid should affect the final concentration of phosphate buffer. right?

Neither "yes" nor "no" are correct answer.

Sad that you both attempt to guess instead of doing the math.
94
Yes,

That's not a correct answer.


Why, what do you mean
You cut out only the Word yes
Should it be NO. For what reason?


95
It is the question doesn't need the calculation. This is the yes or no question. Why do I need to do the calculation?

Learning opportunity - once you do the calculations you will realize where is the mistake in your thinking.
96
So the addition of phosphoric acid should affect the final concentration of phosphate buffer. right?

Have you tried to calculate?

Why does it need a calculation to confirm? If you we prepare the 5 mM ammonium phosphate buffer by adding salt to have 5 mM, then adjusting the pH with phosphoric acid, isn't it very obvious that if some of the phosphoric acid will be included as phosphate as it is clear that phosphoric acid is phosphate as well?

My original question in the post was:
"If there is instruction that 'prepare a 5.0 mM phosphate buffer solution by adding 5mM of ammonium phosphate monobasic and then adjust the pH to x.x with H3PO4 solution', can we still call this solution a 5.0 mM phosphate buffer? My concern is that we don't know how much H3PO4 solution is added. It doesn't matter for molarity calculation?"

Based on what you said, it seems obvious that the adjusting the pH with H3PO4 will increase the amount of phosphate in the buffer which has already 5mM of ammonium phosphate monobasic, so the molarity of phosphate will increase and it can't stay the same or decrease.

It is the question doesn't need the calculation. This is the yes or no question. Why do I need to do the calculation?
97
Organic Spectroscopy / Reading materials about functional groups
« Last post by ohi1244 on March 18, 2024, 03:36:27 PM »
Hi,

I am a graduate student working at the Polymer division. My research involves chemical reactions that change the functional groups of both monomers and polymers. Modifying the functional group changes the overall polarity, and the solvent also changes. However, my understanding of the change in the functional groups and its impact on polarity is unclear. I can not plan on changing groups and predicting suitable solvents yet. Can anyone suggest some reading materials regarding that? I want to reach this stage of thinking, "Okay, maybe changing this into that functional group and that solvent might work."

Thanks in advance :)
99
So the addition of phosphoric acid should affect the final concentration of phosphate buffer. right?

Have you tried to calculate?
100
Yes,
generally if we say to prepare a 1 M Phosphate buffer, then all phosphates and phosphoric acid is in summery.
To calculate use Henderson Hasselbalch equation and the pKa values for the different phosphates according the pH to achieve.
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