Buffers Definition and 39 Threads

Does there have to be both a salt and the conjugate acid/base of the anion/cation to create a buffer? Or can just a salt (e.g. ammonium formate) be a buffer? Does a buffer require a salt that contains the same conjugate base as the acid, or not necessarily? Thanks.

Here I used Henderson Hesselbach equation in both the cases , I.e pH= pKa + log( [(PO4)3-]/ [H3PO4]) here pKa of phosphoric acid is 2.16 but the problem Is in both the cases the log part is same and Pka is also same so both will cancel out, and how can we solve? It is confusing.

Let's keep things simple. I have pure water. pH = 7. I want to add a buffer. I add the weak acid. It dissociates little. So the pH is still close to neutral. So far so good. The problem is, we are also adding conjugate base (the conjugate base is strong). Why doesn't the added base consume the...

Hi, I'm trying to calculate the slope of a pH probe using 7.0 and 10.0 buffer solutions. I've been searching for hours but all examples use 7.0 and 4.0. I've calibrated my probe using the 7.0 and 4.0 buffers and calculated the slope, then I used 7.0 and 10.0, used the same math for the slope and...

Hemoglobin works as a buffer. It has 6 times more buffering power than plasma proteins. My book says that Hemoglobin carrying CO2 (deoxyHb) is a stronger buffer than Hemoglobin carrying O2, because deoxyHb dissociates less (i.e. it forms a weaker acid = a stronger buffer). I don't understand...

Homework Statement Calculate the volume of 0.10M phosphate solution to mix to prepare 100mL of a buffer with pH 6.0 starting with 0.10M stock solutions of NaH2PO4 and Na2HPO4. The pKa for this reaction is 7.21. Homework Equations pH=pHa+log( [A-]/[HA]) The Attempt at a Solution When I did it...

Homework Statement Prepare a buffer solution of pH 3.746 from 25 mL of 0.244 M weak acid with pka 3.54 What volume, in mL, of 0.275 M NaOH would need to be added? I think that I have the answer but I am not sure, could you look over the working to check? Also, would you do this differently...

Homework Statement You have 725 mL of an 0.55 acetic acid solution. What volume (V) of 1.30 M NaOH solution must you add in order to prepare an acetate buffer of pH = 4.99? ( The pKa of acetic acid is 4.76.) [/B] Homework Equations pH = pKa + log A/HA Ratio of A- to HA = 10^(pH-pKA)[/B]The...

Hi I was working on delay-lines and I wanted to know if a pulse is delayed by 10 pulse lengths through a delay-lines than what is the corresponding storage bit for that delay line. Thanks

Hey guys, So I have been running some simulations where I am creating a BPF around the FM band and when I measure the signal on the output, it's much lower than my original signal. So I thought if I put a buffer between the LPF and HPF to electrically isolate the circuits this would help, but...

Homework Statement I'm trying to implement the function F = A'BC+ABD+AB'D' using 3 tri-state buffers. Apparently I'm supposed to connect the buffers together and use C, D, and D' as inputs to buffers. I'm supposed to pass A and B through logic to get the input signals. I'm supposed to...

Homework Statement If a weak acid, HA, is 3% dissociated in a 0.25 M solution, calculate the Ka and the pH of the solution. Homework Equations pH = (pKa - log[HA])/2 The Attempt at a Solution Honestly, I'm not even sure where to start. I don't have the pH or the pKa - how am I...

I have two questions about pH of buffers. It's a general chemistry class, but the questions aren't similar to anything we've had yet. Homework Statement A buffer is prepared by adding 0.96 L of 0.96 M HCl to 762 mL of 1.4 M NaHCOO. What is the pH of this buffer? [Ka(HCOOH) = 1.7 × 10-4]...

Homework Statement As a technician in a large pharmaceutical research firm, you need to produce 100.0 mL of 1.00 M potassium phosphate buffer solution of pH = 7.14. The pKa of H2PO4- is 7.21. You have the following supplies: 2.00 L of 1.00 M KH2PO4 stock solution, 1.50 L of 1.00 M K2HPO4...

Homework Statement A Chemist wishes to prepare 250mL of buffer that has a Ph of 4.50. Starting with 100mL of 0.12 mol L acetic acid and a supply of 0.10 mol L NaOh. 1) explain how this can be done 3) how much 0.20 molL NaOH must e added to this buffer to raise the pH to 5.1? 3) if the...

Homework Statement An buffer is made from a 0.1M acid and a 0.25 M salt. According to the equation pH = pKa - log[acid]/[base] the ratio acid:base is 1:2 What volumes are required to make a 1 dm3 solution? Homework Equations The Attempt at a Solution According to the 1:2 ratio we would need...

"of the same concentration" buffers Homework Statement In the question below what is the signifcance of them saying "of the same concentration" thanks http://www.thestudentroom.co.uk/attachment.php?attachmentid=113982&d=1321805514 Homework Equations The Attempt at a Solution

This is an example calculation about the phosphate buffer system from my Biochemistry textbook. Homework Statement If the total cellular concentration of phosphate is 20 mM (millimolar) and the pH is 7.4, the distribution of the major phosphate species is given by pH = pKa + log10...

An buffer solution consists of a mixture of a weak acid and its salt (conjugate base and a cation) or a mixture of a weak base and its salt (conjugate acid and an anion). When you titrate (for example) a weak acid with a strong base, then at the half equivalence point, there are equal...

I don't understand how to do this problem, but i Understand how to do the reverse of it. "You have 25mL of 0.10M nh3 solution. How many grams of nh4Cl do you need to add to make a buffer with a ph of 9?) answer is 0.18M of nh4+. What I've done is set up the initial table. nh3 + h20...

Here's a solved chemistry problem: http://answers.yahoo.com/question/index?qid=20100731143735AAjKe10 Why did the answerer not use the H-H equation at the very end? Please Help. The H-H equation and the Ka= (H)(A)/(HA) equation (what was used in the problem) both use the same inputs...

Calculate final pH of 25 ml buffer 0.1 M CH3COOH/CH3COO, pH=3.50, after the addition of 1.00 ml of 0.1 M HCl. 3.50=4.75+log(base/3.16x10-4) Base = 1.78x10-5 M Acid = 3.16x10-4 M Mole base = 0.000712 - 0.0001 = 0.000612 Mole Acid = 0.01264 +0.0001 = 0.01274 Mole Acid...

Homework Statement Overall goals: Your first task will be to make a buffer solution of defined pH. Part of your grade will be based on how close your solution comes to the desired pH. Your second task will be to titrate your buffer using 0.5 M NaOH or 0.5 M HCl until the buffer “breaks”...

Homework Statement You are titrating 30.0 mL of .3 M CH3NH2 with .15 M HNO3 Kb = 4.4 x 10^-4. Calculate pH: -initially -after 10.0 mL of acid has been added at the half equivalence point at the equivalence point when 70 mL of acid has been added.Homework Equations not sure. . . The Attempt...

Homework Statement I'm a little confused, let's say i do a titration curve for a weak acid, at some point there's a buffering range near the pKa. Like i know that if we add a strong base like NaOH to acetic acid in a water solvent, then the OH- will combine with the H+ (hydronium ion) which...

I am currently using a pulse generator with a reasonably fast rise-time (something like 1 ns) for some experiments. It works well as long as I am using e.g. 50 Ohm loads but the problem is that it can't source much current, meaning it doesn't work well for lower impedances. Now, my problem is...

Homework Statement I need to work out the maximum compression of buffers for a train with 1.2kg mass, traveling at 0.45m/s and the spring constant, k, is 4.8x10^3 Nm^-1 Homework Equations I tried using 1/2kx^2 but I don't know if I am doing it right The Attempt at a Solution I...

Homework Statement Calculate the pH after 0.030 mol NaOH is added to 1.00 L 0.100 M HC3H5O2 and 0.100 M NaC3H5O2 Homework Equations Ka=[H+][A-]/[HA] pH=-log([H+]) or 14-pOH=ph The Attempt at a Solution HC3H5O2 <-> H+ + C3H5O2- NaC3H5O2 <-> Na+ + C3H5O2- I know that Na+ has no...

Homework Statement This question is for a lab write up. We prepared a 0.1 M citrate buffer with pH 4.0, we then diluted our buffer with deionized water 20 fold and then 50 fold. The subsequent changes in pH are as follows, 20 fold pH = 4.10 50 fold pH = 4.14 This confuses me because I have...

Hi there I was wondering if anyone could help me with this buffers question ... For which of these liquids is the pH likely to change least if a splash of concentrated sulphuric acid is added? Justify your answer: a) 0.1M hydrochloric acid solution b) 0.08M ethanoic acid/0.02M potassium...

Homework Statement A mixture containing 500ml of .1 M HC3H5O2 (acetic acid) and 500 ml of .1 M NaC3H5O2 what is the pH?Homework Equations can someone walk me through this? i know the answer is 4.89 but I am not sure how to get that. I am not even entirely sure how to set up the equationThe...

Very Urgent: Need Help With Buffers! I have a test coming up on Tuesday and I have no idea how to do buffers, I don't understand what Value of the Ka we are suppose to use from the chart. I get the equation a little bit: [H+]= Ka x moles HB/moles of B- I am very lost please help!

You have 35.00 mL of a 0.350 M aqueous solution of the weak base NH2OH (Kb = 6.6 x 10^-9). This solution will be titrated with 0.350 M HCl. (a)How many mL of acid must be added to reach the equivalence point? (b)What is the pH of the solution before any acid is added? (c)What is the pH of...

I understand the henderson-hasselbalch equation, and how the pH of a solution depends on the ratio of acid to its conjugate base. However, I don't understand how this concept can be related to solutions that are extremely diluted. For example, let's say you have 0.00001M acid+c.base...

hi guys need some help with buffers heh anyways my query is say i have a buffer system, then i add say a strong base or a strong acid, then the ph changes, what's a general statement i can make for these observations regarding the h+ ion concentration and stuff. I know that if i have the...

Chemistry Buffers Theory ! hi guys need some help with buffers heh anyways my query is say i have a buffer system, then i add say a strong base or a strong acid, then the ph changes, what's a general statement i can make for these observations regarding the h+ ion concentration and stuff. I...

I have two homework questions that don't make sense at all. I don't really know what formulas to use exactly. Here they are: 1. Molar mass of a certain metal carbonate, MCO3, can be determined by adding an excess of HCl acid to react with the carbonate and then "back-titrating" the remaining...

According to theory, which amounts of the following acid and its conjugate base would you need to prepare 150 ml of a 0.3 M phosphate buffer at pH 7.9? Use the pKa table below to help you in your answer. H3PO4 <–> H2PO4- + H+ pKa = 2.3 H2PO4- <–> HPO4-2 +...

what is the difference between a non-reducing and a reducing buffer? :rolleyes: and what does it mean with non-reducing and reducing? thanks a bunch!