What is Buffer: Definition and 198 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. S

    Unity Gain Buffer: Why R1 Must be Infinity

    all of the electronics textbooks say that you can make a unity gain buffer out of a non inverting amplifier by making R2 = 0 and R1 = infinity. Why does R1 have to be infinite? The TF for a non inverting amp is 1 + r2/r1, so as long as r2 = 0, and R1 should make a unity gain buffer, right...
  2. S

    Chemistry - Adding Strong Acid to Buffer

    Homework Statement A beaker with 135 mL of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.1 M. A student adds 7.80 mL of a 0.400 M solution to the beaker. How much will the pH change? The pKa of acetic acid...
  3. S

    Question: Adding Strong Acid to Buffer

    A beaker with 135 mL of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.1 M. A student adds 7.80 mL of a 0.400 M solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.76. What I did...
  4. K

    Is Weak Acid Titration a Buffer Problem?

    Buffer problem or not?? I have this problem and I worked it out completely, got my answers, and breathed a sigh of relief. Then, when I was looking through my notes and the book I noticed that the problem may have to be done completely differently because it might be a buffer problem. Can...
  5. K

    Is It a Buffer Problem in Weak Acid-Strong Base Titration?

    Buffer problem or not?? I have this problem and I worked it out completely, got my answers, and breathed a sigh of relief. Then, when I was looking through my notes and the book I noticed that the problem may have to be done completely differently because it might be a buffer problem. Can...
  6. T

    Forming precipitate in buffer solution

    Homework Statement The solubility of a hydroxide M(OH)2 is .0090 g/liter. Molecular weight of M(OH)2 is 150. If 1.0 g of MSO4 is dissolved in 500 ml of water buffered at pH 8.5, will a precipitate form? Homework Equations pOH + pH = 14 molarity = mol/liter The Attempt at a...
  7. D

    Methods for Making Buffer Solutions: A Comprehensive Guide

    What methods are there to make buffer solutions? Could anyone outline them? thanks.
  8. K

    Potassium Permanganate Reduction in Aqueous Buffer

    Hello everybody, I'm told that potassium permanganate is dissolved in an aqueous buffer of ammonia and ammonium at equal concentrations (1M), and treated with 1M sodium hypochlorite, the permanganate ion is reduced to insoluble manganese dioxide as the hypochlorite ion is oxiddized to...
  9. K

    Exploring Using LIGO as a Photon Buffer for Quantum Eraser Experiments

    Just a few questions for anyone. I am trying to buffer photons for a long delay quantum eraser. Is there anyway to convert one arm of a 4km LIGO interferometer into a high-fidelity photon buffer? If a beam is merely reflected once down the length of the tube, it is stored for ~13 µs with...
  10. L

    Calculate pH of Buffer Solution After HCl Added

    Question A buffer solution is prepared by mixing 600.0 ml of 0.600 M HClO and 400.0 ml of 1.00 M NaClO. Calculate the pH of the solution after 40.0 ml of 3.00 M HCl is added to the buffer. For HClO, Ka = 3.0 X 10^-8. Work so Far A buffer solution os prepared by mixing 600.0 ml of 0.600 M...
  11. L

    Calculate the pH of Buffer Solution with Ka=1.34x10^-5

    Question A buffer solution is prepared by mixing 380.0 ml of 0.250 M propionic acid, C2H5COOH, and 120.0 ml of 0.350 M sodium propionate, C2H5COONa. Calculate the pH of the prepared buffer solution. For propionic acid, Ka = 1.34 X 10^-5. Work thus far We have this C2H5COOH <-->...
  12. A

    How to determine if the mixing of two solution would result in buffer solution?

    Homework Statement Which of the following mixtures would result in buffered solutions whn 1.0 L of each of the two solutions are mixed? (i) 0.10 M sodium chloride and 0.10 M sodium nitrite (ii) 0.10 M sodium chloride and 0.10 M ammonium chloride (iii) 0.10 M hydrochloric acid and 0.10 M...
  13. A

    A buffer problem, I need serious help

    A buffer problem, I need serious help! 3. Blood has a normal pH of 7.35-7.45 and contains two major buffer systems. It is important that the pH of blood remains relatively constant because at pH below 6.8 or greater than 8.0, cells cannot function properly and death may result. The HCO3-/CO2...
  14. B

    Did I Prepare My Phosphate Buffer Solution Correctly?

    Hi everybody! I want to prepare 1000 ml of 0.1M phosphate buffer solution, pH = 7.0. I used Henderson Hasselbach's equation: pH = pka + log [salt]/[acid]. I obtained 0.062 moles of H2PO4- and 0.038 moles of HPO42-. Where I am wrong? Thanks a lot! B
  15. P

    Calculating pH of Buffer Solution with HCl Addition

    Homework Statement A buffer solution was formed by mixing 30ml of 0.1M sodium acetate and 15ml of 0.1M HCl a) Calculate the pH of this buffer solution. b) Calculate the pH of this buffer solution after the addition of 15ml of 0.1M HCl. Homework Equations pH = pKa + log[salt]/[acid]...
  16. R

    Creating Buffer pH 3.9 | 0.2M NaOH, 0.2M Acetic Acid

    Homework Statement You need to prepare 2000 L of buffer pH 3.9. You have available 0.2 M NaOH solution and 0.2 M Acetic acid (pKa=4.8). How much of each solution do you need? Homework Equations I know that I have to use the H-H eqn: pH = pKa + log([HA]/[A-]) The Attempt at a...
  17. P

    Calculating pH of Mixed Solutions: HCl and Sodium Acetate, Acetic Acid and NaOH

    Homework Statement Calculate the final pH of the following solutions: a) 65.0 ml of 0.105 M HCl and 100 ml of 0.118 M sodium acetate solutions are mixed. b) 100 ml of a 0.109 M acetic acid and 100 ml of a 0.123 ml NaOH solution are mixed. Homework Equations pH = pKa = log...
  18. R

    Titrating weak acid buffer with strong acid after the base is used up

    Homework Statement I'm making a table on excel with the calculated pH of the solution vs the actual measured pH from the lab. My problem is finding the pH of a acetic acid-acetate buffer that has been titrated with HCl, once the moles of HCl are greater than the initial quantity of mols of...
  19. L

    Solve Buffer Problem: 1.00L 1.80 mol/L, pH 4.50, NaC2H3O2, pKa 4.74

    Question: A buffer with pH 4.50 is needed. You have 1.00L of 1.80 mol/L solution. How many grams of Sodium Acetate (NaC2H3O2, molar mass 82.0 g/mol) must be added to give a pH of 4.50? pKa of acetic acid is 4.74. How to solve this problem? thanks for help.
  20. S

    Which of the following solutions result in a buffer ?

    Homework Statement 2. [1pt] Which of the following solutions result in a buffer ? a) 0.100 L of 0.250 M NH3 + 0.050 L of 0.250 M HCl b) 0.100 L of 0.250 M NH3 + 0.100 L of 0.250 M HCl c) 0.100 L of 0.250 M NH4Cl + 0.050 L of...
  21. E

    Creating a pH 6.7 Buffer Solution with Imidazole and C3H5N2Cl

    I have worked through the problem and spent quite a bit of time on it but am not extremely confident in my solution. I would just like someone to check my work. Cheers. Homework Statement -Need 0.4 L of an aqueous buffer solution of pH=6.7 -Have access to 0.02 M HCl, 0.02 M NaOH, 0.01 M...
  22. U

    Solubility combined with Buffer solutions ugh

    Homework Statement Calculate the solubility of C6H5COOAg(s) in a buffer solution that has a pH of 3.20. (Ka = 6,5 x10^-5M ; Ksp = 2,5 x10^-5M^2) a) 0,0164M b) 0,0050M c) 0,0287M d) 0,0012M Homework Equations Henderson-Hasselbach, Ksp equation The Attempt at a Solution This is...
  23. J

    Analytical Chemistry involving buffer

    Homework Statement What volume of 0.200M HCl must be added to 250.0ml of 0.300M sodium mandelate to produce a buffer solution with a pH of 3.37? Homework Equations The Attempt at a Solution For 2 and 3, can I use the equation pH = pKa + log [A-/HA]? but for HCl isn't that 100%...
  24. F

    Creating Buffer Solutions w/ NH4Br - Is it Possible?

    Homework Statement Can NH4Br be used to create a buffer solution? Homework Equations N/A The Attempt at a Solution I said yes because NH4+ is a weak acid, and its conjugate base, NH3 can be added to create a buffer solution. However, I am not sure whether having Br(the conj. base...
  25. R

    Buffer Solution pH: Impact of Adding 1L of 5pH on a 100L Solution

    what will be the new pH of a 100 lt solution if 1 lt buffer solution of 5 pH is added to it
  26. S

    How to write an equation for buffer reacting with excess base?

    I have a conjugated acid + excess base (OH-) ---><---... I don't know how to write the part on the right. Help.. Thanks.
  27. S

    Explaining Resistance in pH of Buffer: Strong vs Weak Acids

    could the equation - pH=pKa+log([A]/[HA]) - be applied for the case of strong acid? Although the percentage of dissociation of strong acid/base is very high, there still exists a equilibrium, right? secondly, if i tried to explain the resistance in pH of buffer *in terms of* the above...
  28. F

    Understanding pH and Buffer Solutions: Acid-Salt Ratio and pKa vs. pH and pKb

    This is not a homework question, so I cannot give exact values or anything, sorry. If we have to make a buffer solution, and we know the pH and the pKa of the acid we are going to use, would it be true to say that if the pH < pKa, we will need more of the weak acid than salt? If pH > pKa, we...
  29. S

    Reacting OH- with CO2 in a Buffer Solution: Which Molecule Takes Priority?

    Here's the buffer solution H2O + CO2 <=> HCO3- + H+ so the question is why when OH- is added to the solution it reacts with CO2 to get HCO3- and H+ :confused: how do you know which one will OH- react with?Why doesn't the OH- react with the H+ :confused:
  30. Hootenanny

    An Introduction to pH and Buffer Solutions Calculations

    An Introduction to pH and Buffer Solutions Calculations [work in progress] This is a work in progress 1. pH and Strong Acids pH is defined as the negative logarithm of the hydrogen ion concentration in a solution; pH = - log10[H+(aq)]. (From this point forward 'log' will represent log to the...
  31. T

    Ph and buffer solutions help

    Hey I have been having a lot of trouble in solving these problems and I have exams soon and I really don't know where to start, I know u aint meant to give the answers so instead would someone please go through all of the steps to finish this! I really need some kinda help, This question was in...
  32. A

    Determining Minimum NaOH Amount for 0.4M Acetic Acid Buffer Capacity

    What is the smallest amount of solid NaOH that will exceed the buffer capacity 500mL of a buffer that is 0.4M in acetic acid and 0.15M in NaOAc? a)5.69 b)5.16 c) 4.74 d) 4.31 e)3.00 grams Since this is a strong base, we only need to deal with the 0.4M of acetic acid. so 0.4M *.5L =...
  33. M

    How Do You Calculate Buffer Capacity in a Mixed Acid-Base System?

    Ok, I have a problem... I have a buffer consisting of acetic acid and sodium hydroxide to which I add HCl (solution 1) and NaOH (solution 2). I'm supposed to find the moles of HCl produced and the moles of NaOH produced in each one. I know the volume of acetic acid is 25.00mL and the volume of...
  34. N

    Finding pH of a buffer solution

    Hi. I was wondering if someone could please explain how to do this question. Find the pH of 1 L buffer (1 mol/L CH3COOH, 1 mol/L CH3COO-) when 0.1 mL 1 mol/L HCl is added. Help would be appreciated. Thanks in advance.
  35. D

    How to Prepare 0.1 M Tris-HCl Buffer: Step-by-Step Guide for Chem Gurus

    Would appreciate some assistance from some chem gurus :smile: Trying to make the calculations necessary to prepare 0.1 M Tris-HCl buffer. I have 80mL of a 0.1 M tris solution and need to find the volume of 1 N HCl required to adjust the pH of Tris to 8.0. I believe I need to use the...
  36. I

    What is an octal buffer and how is it used in electronic circuits?

    Hello, I am new to electronics and have been reading as much as I can about the subject when time permits. I am doing a project to make an adapter to hook a ttl magnetic swipe reader to my computer via the gaming port. There are also plans to make an adapter that would allow you to connect it to...
  37. S

    Diluting 0.01 M HCl to pH 8.0: Question & Explanation

    I have a question about acid and base rxns. For example, if I have a solution of 0.01 M HCl which has pH 2.0. How much should I add H2O to dilute the solution to pH 8.0. I am not sure what to do and how can I explain this problem. Thanks
  38. E

    Determining Buffer Systems: NH3/NH4NO3

    Here's my question: State whether each of the following solutions is a buffer system or not. a) KH2PO4/H3PO4 H3PO4 is a weak acid H2PO4- is the conjugate base derived from the salt thus, this is a buffer system b) NaClO4/HClO4 not a buffer system b/c HClO4 is a strong acid c)...
  39. S

    Making 25 mM Tris-phosphate Buffer (pH 7.8)

    how can i make this buffer? i know how to make Tris- HCl buffer, but how about this one? what is the acid and base here? 25 mM Tris-phosphate (pH 7.8) any ideas? thanks.
  40. A

    Understanding Equilibrium and Buffer Solutions

    Hiya, I am just having abit of an issue understanding the whole concept of this particular chapter. If I have a mixture that is at equilibrium, it implies that the mixture can undergo a forward and reverse reaction ?? So then a buffered solution is also at equilibirum but is composed of an...
  41. R

    What purpose unity gain buffer amplifiers serve

    urgent help needed Can anyone tell me what purpose unity gain buffer amplifiers serve and why do you connect 2 low pass filters of same corner frequency by cascading them using one of these op amp buffers and not directly together. Also can you show me the diagram of this and where the...
  42. P

    Testing Buffer Solutions with Cabbage Dye Indicator

    I am very stuck on this question and I am hoping someone can help me with this. We did this in lab and mine did not come out right, but I still have to turn it in and my lab teacher said to figure it out! Buffer solutions using a cabbage dye indicator: Which of these is a buffered solution...
  43. J

    Calculate Buffer Effect of Adding HCl to Ethanoic Acid Solution

    Hi ppl, could anyone give me a hint as to how to calculate this: Calculate the effect of adding 10cm3 of hydrochloric acid of concentration 1M to 1dm3 of a buffer. The buffer is a solution of ethanoic acid(Ka=1.8 * 10^-5 M) at a concentration of 0.1M and sodium ethanoate at 0.1M. Thanks...
  44. S

    Lysis Buffer: Help Deciphering Protocol

    lysis buffer- help! the protocol for the lysis buffer i use is: 5mM Tris 1mM EDTA pH7.4 does it mean that the lysis buffer has to be pH7.4 or does it mean that the EDTA buffer alone is ph7.4? can you guys tell me which one of these options is correct? 1. add EDTA and Tris to the same...
  45. E

    How to Prepare a Buffer Solution with a pH of 12.50 Using Given Reagents?

    Got a tough problem I have no clue how to do. I have to prepare 500mL of a buffer solution with a pH of 12.50 and must be at least .10 M. The only reagents I have are: solid sodium dihydrogen phosphate dihydrate NaH2PO4 x (H2O)2 Distilled water 1.00 M NaOH(aq) 1.00 M HCL(aq) Not all...
  46. R

    What caused the low pH in my Tris-HCl buffer?

    I don't know if I can effectively convey what I am doing here, but I am going to try because I need the help. I am trying to determine my ratio of acid to base and subsequently make a .5M Tris-HCl buffer utilizing Tris base, and concentrated HCl. By my calculations I get a 19.05 parts acid/1...
  47. Astrophysics

    How do oceans act as a buffer?

    Does anyone have any reliable information about how oceans work as a buffer? I'm not sure if 'buffer' is the correct word, but with buffer i mean a substance, which exists out of a weak acid and it's conjucated base in an equal scale. I thank you in advance, Yasha :smile:
  48. G

    Solving a Buffer Problem in Chemistry: pH Calculation

    here is a buffer problem in my HW that I'm not sure how to do. Plz help me. Plz show me how. Thanks a lot. Formula: pH = pKa + log([B-]/[HB]) ***A buffer is made up of 0.500 L each of .300 M KH2PO4 and .400 M K2HPO4. Calculate a) The pH of the buffer after the addition of 0.0500 mole of...
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