Please verify that the pka of pyrrole is 6.04 and the pka of imidazole is 6.95. Why are they different? Doesn't pysrrole have one more bonded H in the ring structure than imidazole? I would expect slightly more acidic behavior

1,833 results
  1. chemistry

    In protein precipitation, two liters of 5mM buffer solution with pH 5.2 is needed in the isolation of albumin. Which among the buffer solutions is best fitted for the said purpose?justify your answer. a. acetate buffer with pka=4.73? b. tris-aminomethane

  2. chem

    rank strongest acid to weakest acid? rank strongest acid to weakest acid H3CNH2 CH3C (triple bond) CH CH2=CHCH3 H20 CH4 i tried to rank them using the Pka values but I couldn't find the pKa value of the alkyne and I thought the H3CNH2 was the strongest but

  3. Chemistry

    100 mL of 1.0 M formic acid (HCOOH) is titrated with 1.0 M sodium hydroxide (NaOh). The Approximate pKa is 4 At the pKa, what fraction of the carboxyl group will have been converted to COO-?

  4. Chemistry

    The question is: what is the ratio [NH3/[NH4+] in an ammonia/ammonium chloride buffer solution with pH= 10.00? (pKa for ammonia=9.25) When working the problem, I tried to solve it a bit backwards, in that I plugged in each of the multiple choices I was

  5. chemistry buffers

    What molar ratio of HPO4 2- to H2PO4 - in solution would produce a pH of 7.0? Phosphoric acid (H3PO4), a triprotonic acid, has pKa values: 2.14, 6.86, and 12.4. Only one of the pKa values is relevant here. how do i know which pka value to use.. please

  6. Chemistry

    Given the following table of pKa values, at a pH of 4.5 which substance exists predominantly in the protonated form? Acid pKa Value HNO3 -1.3 HSCN 4.0 HCN 9.4 HoCl 7.5 A. Only HNO3 B. Both HCN and HOCl C. Both HNO3 and HSCN D. Only HCN Is the answer for

  7. Chemistry help!!

    Consider the titration of the weak acid HA with NaOH. At what fraction of Ve does pH = pKa - 1? At what fraction of Ve does pH = pKa + 1? Calculate the pH at these two points plus Vb = 0, 1/2Ve, Ve and 1.2Ve, if 100 mL of 0.100 M anilinium bromide (pKa =

  8. chem

    Malonic acid and succinic acid each have two different pKa values. Malonic Acid pKas: 2.85 and 5.70. Succinic acid pKas: 4.20 and 5.60. Explain clearly why the first pKa of malonic acid is lower than the first pKa of succinic acid, and why the second pKa

  9. Chemistry

    Given the following table of pKa values, at a pH of 4.5 which substance exists predominantly in the protonated form? Acid pKa Value HNO3 -1.3 HSCN 4.0 HCN 9.4 HoCl 7.5 A. Only HNO3 B. Both HCN and HOCl C. Both HNO3 and HSCN D. Only HCN Someone please help.

  10. chem

    What is the strongest acid among the following? a. CH3COOH b. (Cl)CH2COOH c. (Cl)2CHCOOH d. (Cl)3CCOOH isnt it the most electronegative if the oxygens are the same? The strength of an organic acid depends on the degree of ionization. The chloride end

  11. chemistry

    Which of the following 0.10 M aqueous solutions gives the LOWEST pH? 1. CH3COOH (pKa = 4.75) 2. CCl3COOH (pKa = 0.52) 3. HF (pKa = 3.45) 4. H3PO4 (pKa1 = 2.12) 5. Because all are acids, the pH is the same for all solutions

  12. Chemistry

    30 mL of 1 M HCl were added to 200 mL of 0.1 M lysine solution having pH = pKa of the side-chain amino group. What is the new pH? pKa values for lysine are 2.18, 8.95 and (R-group) 10.53. Answer is suppose to be 5.57

  13. science(chem) Dr.Bob (activity coeficent)

    When a 0.1M solution of weak acid HA was titrated with a 0.1M NaOH. The pH measured when Volbase=1/2Voleq point was 4.62. Using the activity coeficents, calculate pKa. fA-=0.854 and fHA=1.00 For this I'm confused once again. I know that using the activity

  14. Chemistry

    A chemist performs an acid–base titration using 0.176 M aqueous NaOH as the titrant with 26.15 mL of 0.102 M H2SO4. The endpoint of the titration is detected using phenolphthalein as the indicator. Some acid–base indicators are listed along with their

  15. science

    Given the list of pKa values, which acid will have the largest amount of conjugate base present in the solution at equilibrium? Acid: Pka: H20 15.7 NH3 38 HCL -8 NH4+ 9.2 H2O NH3 NH4+ HCl

  16. CHEMISTRY FOR DR. BOB or anyone else

    A hypothetical weak acid HA, was combined with NaOH in the following proportions: 0.20 mol HA, 0.08 mol NaOH. The mixture was then diluted to a total volume of 1L, and the pH measured. (a) If pH=4.80, what is the pKa of the acid (b) how many additional

  17. Chemistry

    I have a question regarding the titration curve. When the ph is equal pKa that mean there are equal amount of conjugate acid to conjugate base. When a weak acid dissociates for example H3Po4 H+ H2PO4- My problem: I don’t understand how the ph rises

  18. Chemistry

    the pka of acetone is CH3COCH3 is 19.3 which of these bases is strong enough to deprotonate acetone? a)KOH (pka of H20 = 15.7) b)Na+ -C(triplebond)CH (pka of C2H2 = 25) c)NaHCO3 (pka of H2CO3 = 6.4) d)NaOCH3 pka of CH3OH = 15.6) i know the answer is b but

  19. Biochemistry

    How would you make 100 mL of a carbonic acid buffer at 0.5 M and pH = 6.0 using 1.0 M NaHCO3 and either 1.0 M NaOH or 1.0 M HCl and water? so far, I have 50 mL NaHCO3. I plugged that into the Henderson-Hasselbalch equation of pH=pKa + log [A-]/HA] and

  20. Biochem

    You prepare a 1L solution of 0.5 M imidazole. (pKa= 7.05). Calculate the pH of the solution after you add 0.1 moles of HCl. I need to create an ICE table. I also know I need to use the Henderson- Hasselbalch equation but I'm confused on what to plug in.

  21. Chemistry

    Given the table of pKa values, at a pH of 3.5, which substance(s) exist predominantly in the non-protonated form? Acid pKa HNO3 -1.3 HSCN 4.0 HCN 9.4 HOCI 7.4

  22. Analytical Chemistry 2

    Consider the titration of the weak acid HA with NaOH. At what fraction of Ve does pH = pKa - 1? At what fraction of Ve does pH = pKa + 1? Calculate the pH at these two points plus Vb = 0, 1/2Ve, Ve and 1.2Ve, if 100 mL of 0.100 M anilinium bromide (pKa =

  23. chemistry

    A 1.11 M solution of fluoroacetic acid, FCH2CO2H, is 5% dissociated in water. Calculate the value of the pKa of FCH2CO2H. pKa: ?? I dn't even know how to strt with this

  24. chemistry

    Consider an acid, HA, with pKa =3.33 0.025 moles of hydroxide ion are added to 17.4mL of a 0.519 M solution of the acid. What is the resulting pH? I know pKa=-log([Ka]) pH=-log([H+]) I don't know how to link this information. Thanks

  25. chemistry

    We have 1L of 0.1mol/l solution of ammonium chloride, with pKa 9.2 for NH4+/NH3 Place in an increasing order on a pKa axis the different conjugate acid /base pairs present in the solution. Write the equation of the different reactions that may take place

  26. Biochemistry

    Complete hydrolysis of 25 mM ethyl acetate in an enzyme esterase catalyzed reaction is carried out in a 40 mM NaCl solution buffered by 0.2 M Tris-Cl, pH 9.1. What is the pH at the end of the reaction? (For Tris base, which is the abbreviation for Tris

  27. chemistry

    In experiment concerning potentiometric determination of puriy and Ka of KHP, we obtained an experimental pKa of 5.04 and when compared with the theoretical pKa of 5.51, we obtained a % relative error of 192%. Could this error mean that a cerain impurity

  28. Chemistry

    I actually posted this up before and Gk helped out but i don't understand the steps what do i enter for the pka for the first one? __________________________________________ I did an experiment on Buffers: In a polystyrene beaker, mix 20 ml of 0.1M Acetic

  29. Chemistry

    pH indicators change color at their _____. The pH at which the color change happens for a particular indicator molecule depends on its: A. pKa; concentration. B. pKa; Ka or Kb. C. equivalence point; Ka or Kb. D. equivalence point; concentration. Is the

  30. chemistry

    An enzyme-catalyzed reaction is carried out in a 50-mL solution containing 0.1 M TRIS buffer. The pH of the reaction mixture at the start was 8.0. As a result of the reaction, 0.002 mol of H+ were produced. What is the ratio of TRIS base to TRIS acid at

  31. chemistry

    At equilibrium, a solution of formic acid at 25°C has a pH of 2.18. The pKa of formic acid, HCOOH, is 3.74. Which of the following is the initial concentration of the solution? Not sure what to do my thoughts: use henderson hasselback equation pH = pKa +

  32. science- pka- chem

    Please verify that the pka of pyrrole is 6.04 and the pka of imidazole is 6.95. Why are they different? Doesn't pysrrole have one more bonded H in the ring structure than imidazole? I would expect slightly more acidic behavior just on the basis of this.

  33. chemistry

    i posted this already but i got the answer for someone elses question. the pka of acetone is CH3COCH3 is 19.3 which of these bases is strong enough to deprotonate acetone? a)KOH (pka of H20 = 15.7) b)Na+ -C(triplebond)CH (pka of C2H2 = 25) c)NaHCO3 (pka of

  34. chemistry

    i posted this already but i got the answer for someone elses question. the pka of acetone is CH3COCH3 is 19.3 which of these bases is strong enough to deprotonate acetone? a)KOH (pka of H20 = 15.7) b)Na+ -C(triplebond)CH (pka of C2H2 = 25) c)NaHCO3 (pka of

  35. Chemistry

    Which solution will have the lowest pH? a. 0.10 M HClO2, pKa = 1.96 b. 0.10 M HCN, pKa = 9.21 c. 0.10 M HF, pKa = 3.19 d. 0.10 M HClO, pKa = 7.538 e. 0.00010 M HCl Does the lower the pka stronger the acid, means the lower the ph, so the answer is A?

  36. college chemistry

    In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the best indicator for

  37. CHEMISTRY

    In the analysis of food, the nitrogen from the protein is sometimes converted into ammonia which is titrated against a strong acid. Given that the final NH3 concentration (approximate) is 0.2M and that pKa for NH4+ is 9.2, choose the best indicator for

  38. Analytical Chemistry

    Show the predominant form of the amino acid tyrosine at pH=13.9 and ph=7.8. Be sure to include the proper number of hydrogens on heteroatoms and the correct formal charges on atoms. I calculated the pka values for COOH (pka=2.41) NH3 (pka=8.67), and OH

  39. Biochemistry

    Find the net charge of cysteine at pH 8.75 using the follwing pka values: carboxyl group has pka=1.9 amino group pka= 10.7 side chain=8.4

  40. chemistry

    In a buffer solution, if [Aƒ{] < [HA], which of the following must be true? a. pH < pKa b. pH = pKa c. pH > pKa d. pH < 7.00 e. pH > 7.00

  41. Chemistry(Please check)

    an acid with the equilibrium concentration is listed below: 1) HA + H2O = H3O^+ + A- HA= 10^-1 M, H3O=10^-3M, A=10^-3M Calculate the Ka and pKa for the acid. Ka=[10^-3][10^-3] / [10^-1] = 1.00 X 10^-5 pKa = -log[1.00 X 10^-5] = -1.00 Did I do this

  42. chem -please help!!!!!!!!!!!!

    An unknown compound, X, is though to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 and 8. When 75 mL of 0.1M NaOH is added to 100 mL of a 0.1M solution of X at pH 2.0, the pH increases to 6.72. Calculate the pKa

  43. Chemistry

    I have the answer to this question but the book does not explain WHY this is a good buffer solution? It uses pH=pKa - log(base/acid) and shows 7.2=7.2 - log(1). I don't understand why they can only use pKa7.2 and ignore the pKa 12.7. You are instructed to

  44. DrBob222 : need help with the problem

    An unknown compound, X, is though to have a carboxyl group with a pKa of 2.0 and another ionizable group with a pKa between 5 and 8. When 75 mL of 0.1M NaOH is added to 100 mL of a 0.1M solution of X at pH 2.0, the pH increases to 6.72. Calculate the pKa

  45. Chemistry

    Calculate the pI (isoelectric point) of the dipeptide, Lys-Gly, assuming that there is negligible shift in the values of acid dissociation constants from the values of the constituent amino acids. Gly pkA 9.87 an pka 2.35; Lys pka 9.18, 2.16 y 10.79

  46. chemistry- titration

    Once you have calculated your Ka value, use the data to find the concentration of the unknown acids. Vol. of acid solution=25mL concentration of NaOH used = 1M Buffer (pH) = 8.35 at 11.5mL 1/2 11.5=5.75mL which is a pH of 3.58 I did pH=pKa + log(acid/base)

  47. chemistry

    glycine and lysine, have the following values of the relevant acid dissociation constants (pKa) glycine, pKa=2.35 lysine,pKa=10.79 For an aqueous solution of glycine alone, calculate the value of pH at which the ratio of the concentration of neutral

  48. Relative Acidities

    Rank the given compounds on their relative acidity. Here was the order I thought it was but it turned out to be wrong. (i based it based off of sp being most acidic and sp3 being least acidic) STRONGEST HC(triple bond)C-CH3 H2C=CH2 CH3NH2 H2O CH4-->

  49. Organic Chem

    what is the pka of anhydride? i've searched the whole web and can't seem to find the pka of the functional group.

  50. AP CHEM

    What is the pKa for the acid HA if a solution of 0.65 M HA and 0.85 M NaA has a pH of 4.75? ~~~I know you find the ph by doing -log of pka; how do you do the reverse when you have molarity? I am completely lost. :-(

  51. chemistry

    Arrange the acids I) hydrogen selenate ion (HSeO− 4 ), pKa = 1.92; II) phosphoric acid (H3PO4), pKa = 2.12; III) selenous acid (H2SeO3), pKa = 2.46; IV) phosphorous acid (H3PO3), pKa1 = 2.00; in increasing order of strengths. 1. I, III, II, IV 2. None of

  52. chemistry

    Arrange the acids I) hydrogen selenate ion (HSeO− 4 ), pKa = 1.92; II) phosphorous acid (H3PO3), pKa1 = 2.00; III) phosphoric acid (H3PO4), pKa = 2.12; IV) selenous acid (H2SeO3), pKa = 2.46; in increasing order of strengths. 1. IV, III, II, I 2. II, IV,

  53. CHEM!

    Okay well I suddenly got confused for a lab I did We took pH meter than we calibrate it. Then we measure the pH of the acetic acid solution, which was used to determine the Ka of the acetic acid using the first method. We made a 1M solution of NaOH which

  54. Chemistry

    Howdy, I need suggestion on this question. You spotted a mixture of Ala, Arg, Asp, Glu, His, and Lys on an isoelectric focusing where the left and right sides have pH 2 and 13, respectively. After a while, all amino acids stop migration on the strip.

  55. chemistry

    Here are 2 questions I worked out, but need them checked. Also, can't get answer to another question correct unless question 1 is correct. Would you check the first 2 and help me with the third? 1) What is the pH of a 0.05 M solution of TRIS acid (pka =

  56. chemistry lab

    Here are 2 questions I worked out, but need them checked. Also, can't get answer to another question correct unless question 1 is correct. Would you check the first 2 and help me with the third? 1) What is the pH of a 0.05 M solution of TRIS acid (pka =

  57. Chemistry

    What is the pH of a 2.62 x 10^-1 HCN solution? The pKa for HCN = 9.212 I don't know whether to use the Henderson Hasselbalch Equation or just convert pKa to Ka and work it out that way.

  58. Chemistry

    How many moles of solid Mg(OH)2 should you add to 200mL of 0.15M lactic acid solution to produce pH 4.0 buffer? -I don't know how to do this w/0 knowing pKa, but I don't think the point is to look up pKa. Is there some other way to solve this?

  59. biochem

    I need to create a 100ml buffer with a pH of 4.00 using 0.100M Benzoic acid (pKa = 4.20)and 0.180M sodium benzoate. What volume of each material do I need to make this buffer? I think I need to use pH=pKa + log(A/HA)but am not sure if that is correct. Any

  60. chemistry

    Need help with HW question. You have an 11 mM acetate buffer at pH 3.76. What is the concentration (mM) of the acetate ion? Acetic acid has a pKa of 4.76. I used the Henderson Hasselbach eq. by the difference btw the ph and pka and then the conc. of HA and

  61. Chemistry(Please check)

    A 0.0170 M solution of an acid has a pH of 2.5. What is the pKa? i did 10^-2.5=3.16e-3 Then 0.0170 - 3.16e-3=0.01384 ka= (3.16e-3)^2 / 0.01384 = 7.21e-4 pKa = -log(7.21e-4) = 3.14 The pKa is 3.14 Would you agree?

  62. Biochemistry

    All amino acids have two ionizable groups (an alpha-amino group with pKa~9.3, and an alpha-carboxyl group with pKa~2.2). Lysine also has an ionizable side-chain (R) with a pKa of 10.5. What percentage of the Lysine side chain is deprotonated at pH 11.5?

  63. Chemistry

    I am attempting to answer a question which asks to explain the sequence of pKaH values for a series of substituted guanidines (NH2)2CNR where R varies. The order is R = H , Ph , CH3CO , MeO , CN , NO2 pKaH = 14.5 , 10.8 , 8.3 , 7.5 , -0.4 , -0.9 I'm not

  64. chemistry

    You have 100.7 g of saccharin, a sugar substitute, and you want to prepare a pH = 5.80 solution. What volume of solution can be prepared? For saccharin (HC7H4NSO3), pKa = 11.70 (pKa = −log Ka).

  65. Chemistry

    How many moles of conjugate base (Na2HPO4) are present in 40mL of .010M buffer at pH 7.5 vs at pH 6? Buffer was made up of Na2HPO4 and NaH2PO4. pH=pKa +log[A/HA]; pKa=7.2.... When I did the calculations I got the same amount as if it were in a 0.1M buffer

  66. chemistry

    Based on the experimental data, I was able to calculate the experimental pKa value which is 5.04 and the literature value of the pKa for KHP is 5.51. If I would be computing for the relative error between the two pKa's it would be 8.52994555%. But then,

  67. Chemistry

    A buffer system contains 0.30 M NH4+ and 0.15 M NH3. pKa of NH4+ is 9.25. How many moles of NaOH must be added to 1.00 L of this solution to increase the pH to 9.25? Hint: What is the (NH3) / (NH4+) when the pH=pKa?

  68. chemistry Please Help Dr.BOB

    Complete hydrolysis of 25 mM ethyl acetate in an enzyme (i.e., esterase)-catalyzed reaction is carried out in a 40 mM NaCl solution buffered by 0.2 M Tris-Cl, pH 9.1. What is the pH at the end of the reaction? (For Tris base, which is the abbreviation for

  69. Chemistry

    what are the other chemistry forms present in the dichloromethane solution besides the normal neutral forms for benzoic acid and quinine? (benzoic acid,pKa 4.2; quinnie, pKa 8.5)

  70. Chemistry

    When the concentration of a weak acid in solution is equal to the concentration of its conjugate base in solution, then: Would pH=pKa or would it equal pH=pKa + 1 like Henderson-Hasselbalch equation?

  71. Bio

    1.cAMP MOLECULES BIND TO THE ________ subunit of_______ a. catalytic, PKC B. regulatory, PKA C. Regulatory, PKC d. Catalytic, PKA I THINK THE RIGHT ANSWER IS "B", PLEASE HELP

  72. chemistry

    The weak acid HQ has pKa of 4.89. Calculate the (OH-) of 0.500 M HQ This is what I have: pKa = 4.89 so Ka = 10^-4.89 = 1.29x10^-5 Ka = 1.29x10^-5 = [H+][Q-] / [HQ] 1.29x10^-5 = x^2 / 0.046 - x x^2 + 1.29x10^-5x - 5.93x10^-7 = 0 x = [H+] = 7.64x10^-4M pH =

  73. Chemistry

    A solution is prepared by dissolving 0.1 mol of ethanoic acid (CH3COOH) in 500ml of water at 25 C. pKa of ethanoic acid is 4.7. What is the pH of the solution? I'm assuming the equation is pH = pKa + log[Base]/[Acid] but can't get it to work?

  74. organic chem

    . Use the Henderson-Hasselbach equation: pH = pKa + log [A-]/[AH], where A- is the conjugate base and AH is the weak acid. Calculate the pH of an acetate buffer in which the acetate concentration [CH3COO-] is 3.5 times greater than acetic acid [CH3COOH].

  75. org. chem

    How to start these problems out: Please help thank you Use the Henderson-Hasselbach equation: pH = pKa + log [A-]/[AH], where A- is the conjugate base and AH is the weak acid. Calculate the pH of an acetate buffer in which the acetate concentration

  76. PKA VALUES

    I understand that the pH at the half equivalence point gives is the pKa value but could someone explain why this point is the pKa value? HA is a weak acid. HA ==> H^+ + A^- Ka = (H^+)(A^-)/(HA) Solve for (H^+)= Ka*(HA)/(A^-) If we start with, say, 0.1 M HA

  77. Chemistry

    Glutamic acid is triprotic amino acid with pKa values of 2.23, 4.42, and 9.95. You are given a 0.100 M solution of it in its fully protonated form (H3A). How many moles of KOH must be added to 100 mL of this solution to make a solution with a pH of 5.00. I

  78. chemistry

    You need to determine the pKa of a weak, monoprotic acid. You add 0.500 moles of the acid to 1.00 L of water. The resulting pH was 1.87. What is the pKa of this weak acid? You may ignore the autoionization of water. 2.74 3.43 5.38 2.01 1.87

  79. chemistry

    Acid: Pka: H20 15.7 NH3 38 HCL -8 NH4+ 9.2 Given the list of pKa values, which acid will have the largest amount of conjugate base present in the solution at equilibrium? H2O NH3 NH4+ HCl

  80. Chemistry

    Acid: Pka: H20 15.7 NH3 38 HCL -8 NH4+ 9.2 Given the list of pKa values, which acid will have the largest amount of conjugate base present in the solution at equilibrium? H2O NH3 NH4+ HCl

  81. chemistry

    I have already posted this and never got a response, please help. here is my data from lab: Buffer1: HPO4- weight 3.412g; original pH Buffer 2: HEPES wt: 1.090g original pH 10.08 buffer1: pH of 0.1M: 7.5; pH of 0.01: 7.72; pH of 0.001M: 7.87 buffer2: PH of

  82. Biochemistry

    Assuming pKa values of 3.8 for the a-COOH and 8.5 for the a-amino groups and that the numbers in parentheses indicate the pKa values of side chain groups, at what pH would electrophoresis provide the best resolution of the following dipeptides? His (6.0)

  83. biochem

    I mixed 4.50mL of 10.0mM NaOH with .50mL phenol red. I need to calculate the pH of this solution. I have more information in my lab but I am not sure what data I need to look for. As part of the experiment I calculated pKa of Phenol Red. Do I use that pKa

  84. Chemistry

    The pH of a buffer can be predicted using the Hendersen-Hasselbach equation: pH=pKa+ log([conjugate base][conjugate acid]) The choice of the conjugate acid-base pair (as you did in the previous questions) determines the pKa value to be used in the H-H

  85. Chemistry

    You have 30mL of .2M HF being titrated with .15M KOH. The pka is 3.17....half way to the equivalence point you have 20mL of KOH. Find the pH when you add 40mL of KOH . Find the pH when you have 100mL of KOH added. Sol:pH = pKa + log (base / acid) = -log

  86. Plz -- Chem Help

    Posted by Rushi on Sunday, March 15, 2009 at 3:35pm. Question.. Nicotinic acid (niacin) is a monoprotic acid with the formula HC6H4NO2. A solution that is 0.012M in the nicotinic acid has a pH of 3.39 at 25C. what is the acid-ionization constant, Ka and

  87. chemistry

    What is the pH of a solution prepared by dissolving 8.40 g of aniline hydrochloride C6H5NH3Cl in 750 mL of 0.210 M aniline,C6H5NH2? i kno to use the ph = pka + log (base/acid). getting pka isnt the issue, but what do i put into the log (base/acid)?

  88. chemistry

    What is the pH of a solution prepared by dissolving 8.40 g of aniline hydrochloride C6H5NH3Cl in 750 mL of 0.210 M aniline,C6H5NH2? i kno to use the ph = pka + log (base/acid). getting pka isnt the issue, but what do i put into the log (base/acid)?

  89. chemistry

    The pKb of ammonia, NH3, is 4.74 at 25°C. Which of the following is the Ka of the ammonium ion, NH4+? not sure what to do, this is what i have i guess: kb = -log 4.74 ----- pKa + pKb = 14 pKa = 9.26 ka = -log 4.26 = -0.676 ----- Ka = [NH4+][OH-]/ [NH3]

  90. Chemistry

    Strong base is dissolved in 535 mL of 0.200 M weak acid (Ka = 3.16 × 10-5) to make a buffer with a pH of 4.04. Assume that the volume remains constant when the base is added. HA (aq)+ OH^-(aq) -> H2O(l) + A^-(aq) Calculate the pKa value of the acid and

  91. chemistry

    What is the (H3O+) and the ph of a buffer that consists of 0.25M HNO2 and 0.69M KNO2? (Ka of HNO2 = 7.1 x 10^-4) is this right? pH of acidic buffer pH = pka + log(salt/acid) pka = -log ka = -log(7.1*10^(-4)) = 3.15 = 3.15+log(0.25/0.69) pH = 2.71 [H3O+] =

  92. Biochemistry

    Describe the preparation of 2.00 L of 0.100 M glycine buffer, pH 9.0, from glycine and 1.00 M NaOH. a) What mass of glycine is required? The appropriate pKa of glycine is 9.6. b) What volume of 1.00 M NaOH is required? The appropriate pKa of glycine is

  93. biochem

    How do you draw a tetrapeptide from the one letter codes(Amino acids) and also give the pI, if given the pKa values? For example the Amino acids: S,T,G,L So i know i decipher the the codes then to make tetrapeptide i start with the n terminus to the c

  94. bio

    How do you draw a tetrapeptide from the one letter codes(Amino acids) and also give the pI, if given the pKa values? For example the Amino acids: S,T,G,L i need some guidance, so i just look up the codes and draw them attached to each other form n-terminus

  95. chemistry

    what is the pH of the buffer when 4ml of 1M HCl is added to a 100ml buffer solution made using 5ml 1M Na2HPO4 and 5ml 1M NaH2PO4? The pKa for H+ + HPO4- ==> H2PO4 is 6.82. What would happen to the pH if the 100ml buffer had been made up at the starting pH

  96. Chemistry

    'A solution is prepared by titrating a 100.0 mL sample of 0.10 M HF (Ka = 7.2 x 10^-4) with 0.1 M NaOH. What is the pH after 20.0 mL of the 0.10 M NaOH is added?' I'm a little bit confused but here's my ICE chart (in moles): HF________OH-_____F-

  97. Biochemistry

    Show Calculations used in mkaing 250mL of 0.5M sodium acetate ph 4.7. You are given: 1M acetic acid (weak acid) 1M sodium hydroxide (strong base) Sodium acetate buffer: ph 4.7 acetic acid pKa: 4.7 So far this is what I've gotten: pH = pKa + log (A-/HA-)

  98. Chemistry

    The ethylammonium ion, CH3CH2NH3+, has a pKa of 10.81. It reacts with water to form ethylamine, CH3CH2NH2 and H3O+. Which of the following statements is true at pH 7? A.) ethylamine predominates B.) ethylammonium ion predominates C.) the pH is higher than

  99. Chemistry

    In a solution of a weak acid and its conjugate base, which condition has to be true for pH to equal pKa? The concentration of acid has to be greater than the concentration of base. The concentration of acid has to be equal to the concentration of base. An

  100. Chemistry

    Determine the pH of the following solutions: a) A 250.0 mL solution that contains 0.125 M benzoic acid and 0.147 M sodium benzoate. b) The solution in part (a) after 30.0 mL of 0.510 M hydrochloric acid has been added. a. Ka = 6.3 x 10^-5 pKa = 4.20 pH =

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