What is Buffer: Definition and 197 Discussions

A buffer solution (more precisely, pH buffer or hydrogen ion buffer) is an aqueous solution consisting of a mixture of a weak acid and its conjugate base, or vice versa. Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many systems that use buffering for pH regulation. For example, the bicarbonate buffering system is used to regulate the pH of blood, and bicarbonate also acts as a buffer in the ocean.

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  1. C

    Buffer solution working with DNA -- I have to dissolve dried oligos in PBS

    This is the first time I am working with DNA and I have to dissolve the dried oligos in PBS( 10mM phosphate buffer, 100mM NaCl, ph=7.4) buffer. However I don't understand how to do that. I will really appreciate if somebody can please explain me. Thank you in advance.
  2. M

    Finding height of buffer regions and viscous sublayer turbulent flow

    Hi, I was recently attempting a problem about the height of buffer regions and viscous sublayer. Question: A fluid flows through a smooth pipe of diameter 150 mm with flow rate, density and kinematic viscosity of 0.180 m^{3} s^{-1} and a density 700 kg and 0.40 \times 10^{−6} 𝑚^2...
  3. Kaushik

    How does a buffer actually work?

    Buffer is a solution of weak acid and its conjugate base which resists the change in pH when strong acid/base is added to the solution. But how does it work? Consider, HA + H2O ⇄ H3O+ + A- When we add strong acid, the H+ from the strong acid reacts with the conjugate base A- to for HA...
  4. D

    Calculating the pH of a Buffer Solution

    Hi everyone. I'm doing the multi-step problem above, and I've found myself stuck at part 3. For step 1, I determined that the equation that we're dealing with is: $$CH_3CH_2CO_2H + H_2O ⇔ CH_3CH_2CO_2^- + H_3O^+$$ I've also determined that the molar mass of propanoic acid is about 74.08g/mol...
  5. J

    Creating a buffer out of 0.100M solutions

    Homework Statement The questions asks which of the following would make a buffer given that all solutions are 0.100M and you have solutions of acetic acid, sodium hydroxide, and hydrochloric acid. 20.00mL of each solution is mixed. 20.00mL of acetic acid and 30.00mL of NaOH are mixed...
  6. R

    What's the advantage of using a voltage buffer amplifier?

    i want to understand what's the advantage of using a voltage follower
  7. Krushnaraj Pandya

    Calculate pH change of a basic buffer

    Homework Statement to 1 L solution containing 0.1 mole each of NH3 and NH4Cl, 0.05 moles of NaOH is added. The change in pH will be? (pK for NH3=4.74) The Attempt at a Solution I have the solution and the answer is 0.48. The following was the first step calculated initial pH from henderson's...
  8. Krushnaraj Pandya

    Calculate pH of a buffer solution

    Homework Statement Calculate pH of a solution containing 0.1 mole of Ch3cooh, 0.2 mol of CH3COONa and 0.05 mol of naoh in 1 L. (Pka for Ch3cooh=4.74). 2. The attempt at a solution The 0.05 mol of NaOH will react with the 0.10 mol CH3COOH to produce 0.05 mol CH3COONa , and there will bve 0.05...
  9. J

    Which of the following combinations would act as buffered solutions

    Homework Statement Which of the following combinations would act as buffered solutions? a. HCl and NaCl b. CH_3COOH and KCH_3COO c. H_2S and NaHS d. H_2S and Na_2S Homework Equations none really... The acid needs to be weak and the base strong though. The Attempt at a Solution HCl is one...
  10. Dhh1994

    Can pH of a His buffer change during lyophilization?

    We lyophilized 50mg/ml mAb with PI of 7.5 in a 10mM His buffer pH 6.2. Upon reconstitution the pH is 6.5. Does anyone have an explanation for this? I am under the impression His is much less susceptible to pH change during lyophilization as opposed to something like a phosphate buffer. Thanks.
  11. A

    Why is one a buffer solution but not the other?

    Homework Statement A student prepares two solutions: Solution A is prepared by mixing 50cm3 of 0.100mol dm-3 CH3COOH(aq) with 25cm3 of 0.100mol dm-3 NaOH(aq) Solution B is prepared by mixing 25cm3 of 0.200mol dm-3 CH3COOH(aq) with 50cm3 of 0.100mol dm-3 NaOH(aq) Explain why solution A is a...
  12. ReidMerrill

    PH and Molarity of a Buffer

    For a lab I need to create a 0.1M solution of NaOAc buffer at pH 5 It's been a while since I worked with buffers. I'm struggling to find a way to get both the proper morality and proper pH. My first though was to create a 0.2M solution of acetic acid and titrate it to pH 5 using sodium...
  13. Asmaa Mohammad

    Hemoglobin as a Buffer: How It Becomes Weak & Strong Acid

    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...
  14. H

    Volumes of a Buffer using Henderson-Hasselbalch?

    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...
  15. I

    How does a buffer amp not remove all loading effect?

    Homework Statement I recently completed a lab where I set up a buffer amp. Its input was a function generator set at 5Vp amplitude and we placed various load resistors on the output to test Vout on an oscilloscope ( 75kΩ, 3300Ω, 510Ω and 68Ω.) From my data I noticed that the Vout was the same...
  16. I

    Buffer solutions and pKa confusion

    Homework Statement A chemist dissolves 16mmol of a nucleoside diphosphate, CDP, in 1L of an aqueous solution containing Mg2+ and buffers the solution at pH 8.7. The chemist monitor the reaction by measuring the amount of inorganic phosphate produced. No reaction is detected for 30mins, then the...
  17. T

    Distributing a clock signal using a clock fanout buffer

    hi, im trying to distribute a clock signal using a clock fanout buffer. I have an oscillator and i need to get its clock signal to 4 other devices. My first idea was to supply the clock signal of the oscillator to a clock buffer. I have chosen this clock buffer...
  18. J

    Ionic strength of Mcilvaine's Buffer

    Table 1. Preparation of Constant Ionic Strength McIlvaine Buffered Solutions Reference: P.J. Elving, J.M. Markowitz, I. Rosenthal, Analyt. Chem. 28(7): 1179-1180 (1956) pH Desired Composition, G/Liter of Solution Composition, Moles/Liter of Solution Buffer System G/Liter of KCl added per liter...
  19. Fips

    Why isn't there a buffer on an oscilloscope?

    Today in my electronics class, we were introduced to the amp op concept. After going through some fundamentals, the teacher challanged us to find v0 of a simple circuit with a battery and two resistances of 1M ohm each(v0 is in between these resistances). Afterwards he asked us if this same...
  20. T

    Cascaded low-pass filter followed by a buffer amplifier

    Homework Statement 3. FIGURE 3(a) shows a simple low-pass filter followed by a buffer amplifier. (a) Write down the transfer function for the filter. (b) Determine the 3db frequency (fc) if R = 10 kΩ and C = 10 nF. (c) If four such stages are cascaded as shown in FIGURE 3(b), determine the gain...
  21. Natsu1993

    How to prepare 50mM Na2HPO4/H3PO4 buffer, pH 4.5

    The have to prepare the buffer but I really don't know how. Is the any formula for the buffer preparation? Ps. Sorry but one more thing, what does the "/" between Na2HPO4 and H3PO4 mean?
  22. ReidMerrill

    Phosphate Buffer and pH: Would it be Effective at pH 8.5? - Homework Discussion

    Homework Statement Phosphate, present to an extent of 0.01 M, is one of the main buffers in blood plasma, whose pH is 7.45. Would phosphate be as useful if the plasma pH were 8.5? Homework Equations pH = pKa+log[A/HA] Ka1 = 7.11x10^-3 pka1= 2.148 Ka2=6.34x10^-8 pka2= 7.198 Ka3 = 4.22x10^-13...
  23. N

    Buffer solution preparation

    Homework Statement So I have prepare a buffer solution of 100 mL with ph of 4.00 .I have to use acetic acid and NaAc (sodium acetate ) to do so . The sum of the concentration of weak acid and its conjugate base is equal to 0.10 M ca + cb = 0.10 M How much volume of acetic acid and NaAc should...
  24. A

    How to make 0.2 M Tris-Acetate Buffer pH 6

    Hello, I need to make a 0.2 M Tris-Acetate Buffer pH 6 and I can't find a protocol for this specific buffer. I know that I can make a Tris solution (i.e. 12.11 g of tris(hydroxymethyl)aminomethane in water), adjust the pH to 8 and dilute to 1000 mL with water. Is the same true for pH 6...
  25. T

    Buffer solutions acid or base

    Homework Statement Homework EquationsThe Attempt at a Solution From what I know, to make buffer solutions you need a weak acid or base and it's salt. Non of the options has this. What am I missing? Cheers!
  26. K

    How do I find the ph without using Hasselbach's equation?

    Homework Statement hi so in my lab class we made a buffer solution by mixing 20.00 ml of 0.100 M Sodium Hydroxide and 40.00 ml of 0.100 M of acetic acid. We then poured 15ml of this buffer solution into a beaker. So we essentially have 15 ml of this buffer solution in the beaker. We then added...
  27. Titan97

    Buffer action and titration

    If H2A2+ is being titrated with NaOH, a buffer forms. The processes taking place are equilibrium between H2A2+ and HA+ ions, autoprotolysis of water and reaction of OH- ions with H2A2+ ions. As NaOH is added, the concentration of acid tends to decrease but because of the equilibrium ##H_2A^{2+}...
  28. alr1014

    Chemistry Moles of a conjugate base in a buffer solution

    Homework Statement You need to produce a buffer solution that has a pH of 5.70. You already have a solution that contains 0.0200 moles of acetic acid. Using the Henderson-Hasselbalch equation calculate the moles of sodium acetate needed to create a buffer with the desired pH? The Ka of acetic...
  29. A

    Is a 12V Tri-state Buffer Available for Programming PIC Microcontrollers?

    Hello, I'm trying to build a hub to connect several circuits that have a PIC microcontroller and be able to select one of them and download the program to it. The circuit that I have in mind to select and program one PIC microcontroller is this...
  30. W

    Best optimal buffer, highest buffering capacity against naoh

    Homework Statement Group#1: Buffer pH = 4.00 Group#2: Buffer pH = 4.35 Group#3: Buffer pH = 4.70 Group#4: Buffer pH = 5.00 Group#5: Buffer pH = 5.30 Group#6: Buffer pH = 5.60 1. Explain which group should havethe BEST OPTIMAL BUFFER (see choices above). 2. Explain which group has a buffer...
  31. TheExibo

    Create Buffer: Sodium Citrate & Citric Acid

    Homework Statement Using sodium citrate and citric acid, create a buffer solution that will withstand an addition of 20ml of 0.1mol/L HCl or NaOH solution without a significant increase in pH (+/-2). Bonus marks for using the smallest amount of buffer solution. Homework Equations Reaction...
  32. brainbaby

    How a current buffer transistor cancels the early effect (Cascode)

    In the given circuit Q2 is a current buffer tranistor which maintains constant current voltage for Q1 just to cancel the harms of early effect...how does it do so??
  33. C

    Estimating pH for Highest Buffer Capacity from HO2C-C6H4-CO2H & HO2C-C6H4-CO2Na

    Ka values of the 1st and 2nd dissociation of phthalic acid (HO2C-C6H4-CO2H) are given below. Estimate the pH value for highest buffer capacity when a buffer is prepared from 1:1 mixture of phthalic acid and sodium hydrogen phthalate (HO2CC6H4- CO2Na) in water? HO2C-C6H4-CO2H <=> H+...
  34. F

    Guide 34 pH Buffer Sources: Find NIST Traceable Vendors

    Hello! Can anyone recommend a good guide 34 and NIST traceable pH buffer vendor. Our experience with our current vendor has left a bit to be desired, and we need a large variety of standards that limits our supply. Thank you for reading this and any help you may offer.
  35. T

    PH buffer calculations

    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...
  36. S

    Work/Energy Question - Buffer

    Hi, I've attached the question and answer below. I've got (i) but I'm unsure how to achieve the answer for (ii). I've tried using the linear motion equations and also a combination of the kinetic/potential energy questions but haven't had any luck as of yet... Help is much appreciated, thanks!
  37. M

    Buffer solution + equilibrium + Organic compound

    For this question,why Ka =(ch3coo-)(h+)/(ch3cooh) instead of Ka =(ch3coo +x)(x)/(ch3cooh-x) ?
  38. H

    Passing High Voltage/Amperage Through Tri-State Buffer (car LED project)

    Hi guys, I'm a total greenhorn so please bear with me. I'm designing a circuit in which I use a lot of tri-state buffers. All ICs in the circuit will be powered with 5V, but I need to pass 12V (and up to 15A) from the input to the output of the tri-state buffers when the buffer is enabled...
  39. CivilSigma

    Creating a Buffer pH of 9.23: Step-by-Step Guide

    Hello, I have the following problem: What volumes of 0.200 M HCOOH and 2.00 M NaOH would make 500.0 mL of a buffer with the pH of one made from 475 mL 0.200 M benzoic acid and 25 mL of 2.00 M NaOH? I have determined that the pH of the buffer should be 9.23. Now, I am stuck on how I would...
  40. Ramana

    Unity Gain Buffer with Op-Amp 741 for LVDT Sensor

    Hello, Here need a suggestion on Unity gain buffer using op-amp 741. The output i need in the range according to change in LVDT sensor (resistive type). The output of the sensor is 35mv to 3.5 VDC. The circuit i build using op-amp741 as voltage follower where the output is given feedback to...
  41. F

    What happens if an acid is added to this buffer?

    Homework Statement In grapes, there is an equilibrium between tartaric acid and hydrogen tartrate and hydrogen ions: (1) H2T (aq) <=> HT- (aq) + H+ NOTE: "T" stands for the tartrate ion C4H4O6. There is also a buffer system in grapes, involving a solubility equilibrium of potassium hydrogen...
  42. D

    BioRad Turbo Blot Transfer Buffer Composition?

    Recently, my lab has bought a BioRad Turbo Blot Transfer system. It allows for you to do an efficient 7 minute transfer from a minigel to nitrocellulose. The transfer buffer, however is very expensive because you can only purchase it in conjunction with precut nitrocellulose membranes and thick...
  43. Y

    H2PO42- HPO4- buffer system

    Hello Forum! 1g of H2PO4- and 1 g of HPO42- are put together into 100 ml of H2O. What is the pH of the buffer created. Ka1= 7.5x10^-3 Ka2=6.2x10^-8 Ka3=4.8x10^-13 ______________________ Okay. I uploaded my solutions. (Please disregard the part 1.184 g/mol and the 34% on my answers...
  44. R

    Engineering Find voltage for circuits with buffer amp

    Homework Statement Homework Equations The Attempt at a Solution I first found Vab which was 10 by using voltage division on the first device. By connecting CD to AB, the equivalent resistor is 80// 20, 16? I am not sure where to go from here.
  45. A

    Calculate Moles of CH3NH2 Needed for pH 9.55: Buffer Solution

    You want to have a ph of 9.55 with a buffer. How many grames of CH3NH3ClO4 would you add to 800 ml of 0.258 M CH3NH2 to do this. Assume volume remains constant. Kb for methylamine is 4.2x10^-4. My answer is 320g. Can anyone check this please? I have an exam on buffers very fast. You would do...
  46. Q

    Do I Need a Buffer for My ADC When Sharing a Bus with NAND Flash?

    somebody says put a buffer between a bus and an ADC .even if the ADC has an internal buffer. it iminimises the noise feed through,and may improve ADC accuracy by lowering power dissipation. in the project i am working on,the ADC must share 16bit BUS with a nand flash.the bufer is necessary...
  47. Q

    Understanding Buffers: Definition and Composition

    Homework Statement What's a buffer? Homework Equations The most general definition is that a buffer resists changes in pH. However, my textbook and ChemWiki by UC Davis maintain that a buffer is composed of conjugate pairs (i.e. a base and its conjugate acid). The Attempt at a Solution...
  48. mishima

    Simple circuit to demonstrate buffer action/loading effects?

    I was looking for a simple circuit to breadboard that demonstrates how a buffer prevents "loading" effects. I would like to do something like this: 1. Build circuit without buffer where loading effects are observable 2. Add buffer to circuit and observe the elimination of this effect I...
  49. M

    Iodine Clock H2O2/I-/H+ why buffer it?

    The RSC Classic Chemistry Demos list the method for the hydrogen peroxide iodine clock variant as being buffered at pH5.8 with ethanoic acid/sodium ethanoate. Can anyone explain why it might be useful to buffer a clock reaction in this way? It seems this is for a demo rather than a serious...
  50. D

    Interpreting buffer solution reaction

    So it seems I've been seeing two different ways of interpreting buffer solution reactions. One to me seems to work with Le Chatelier's Principle and the other doesn't. I am dropping a strong base, NaOH, into a weak acid/base buffer solution. View A: HA + H2O <--> (H3O+) + (A-) Reasoning: The...
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