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Preparation of pH buffer solutions HOME Email Webmaster Related link: Analysis Buffers For EDTA titrations For Fluoride (TISAB) For Determination of Fe. On this page: Click the links below to jump to the relevant info: The preparation of pH buffer solutions acetate buffers phosphate buffers solid mixture buffers
Phosphates Phosphate salts are known by several names and the correct phosphate must be used to prepare buffer solutions. One phosphate cannot be substituted for another phosphate. Check formula of salt to be certain. Formula
Standardization buffers For pH=7.00 : Add 29.1 ml of 0.1 molar NaOH to 50 ml 0.1 molar potassium dihydrogen phosphate. Alternatively : Dissolve 1.20g of sodium dihydrogen phosphate and 0.885g of disidium hydrogen phosphate in 1 liter volume distilled water. For pH= 4.00 : Add 0.1 ml of 0.1 molar NaOH to 50 ml of 0.1 molar potassium hydrogen phthalate . Alternatively : Dissolve 8.954g of disodium hydrogen phosphste.12 H2 O and 3.4023g of potassium dihydrogen phosphate in 1 liter volume distilled water.
Tris (hydroxylmethyl) aminomethane / Hydrochloric acid
7.0 - 9.00
Sodium tetraborate/ Hydrochloric acid
8.1 - 9.2
Glycine/ Sodium hydroxide
8.6 - 10.6
Sodium carbonate/ Sodium hydrogen carbonate
9.2 - 10.8
Sodium tetraborate/ Sodium hydroxide
9.3 - 10.7
Sodium bicarbonate / Sodium hydroxide
9.60 - 11.0
Sodium hydrogen orthophosphate / Sodium hydroxide
11.0 - 11.9
Potassium chloride/ Sodium hydroxide
12.0 - 13.0
Preparing a Buffer Solution ² This page gives tabulated info on the preparation of buffers by mixing adjusters with a known volume of the primary salt solution, and made up to 200ml with distilled water. BUFFERS 1.00 - 9.00 Buffer A : pH 1.0 - 2.2
Buffer B : pH 2.2 - 4.00
50 ml 0.2 M KCl + mls of 0.2 M HCl
100 ml 0.1 M potassium 100 ml 0.1 M potassium hydrogen phthalate + mls of hydrogen phthalate + mls of 0.1 M HCl. 0.1 M NaOH
pH
mls of 0.2M pH HCl added
Buffer C : pH 4.10 - 5.90
mls of 0.1M HCl added pH
Buffer D : pH 5.8 - 8.00
mls of 0.1M NaOH added
Buffer E : pH 7.0 - 9.00
. 100 ml 0.1 M 100 ml 0.1 M tris KH2PO4 + mls of 0.1 (hydroxymethyl) M NaOH. aminomethane + mls of 0.1 M HCl. pH
mls of 0.1M NaOH added
pH
mls of 0.1 M HCl added
1.00 134.0
2.20 99.0
4.10 2.6
5.80 7.2
7.00 93.2
1.10 105.6
2.30 91.6
4.20 6.0
5.90 9.2
7.10 91.4
1.20 85.0
2.40 84.4
4.30 9.4
6.00 11.2
7.20 89.4
1.30 67.2
2.50 77.6
4.40 13.2
6.10 13.6
7.30 86.8
1.40 53.2
2.60 70.8
4.50 17.4
6.20 16.2
7.40 84.0
1.50 41.4
2.70 64.2
4.60 22.2
6.30 19.4
7.50 80.6
1.60 32.4
2.80 57.8
4.70 27.2
6.40 23.2
7.60 77.0
1.70 26.0
2.90 51.4
4.80 33.0
6.50 27.8
7.70 73.2
1.80 20.4
3.00 44.6
4.90 38.8
6.60 32.8
7.80 69.0
1.90 16.2
3.10 37.6
5.00 45.2
6.70 38.6
7.90 64.0
2.00 13.0
3.20 31.4
5.10 51.0
6.80 44.8
8.00 58.4
2.10 10.2
3.30 25.8
5.20 57.6
6.90 51.8
8.l0 52.4
2.20 7.8
3.40 20.8
5.30 63.2
7.00 58.2
8.20 45.8
3.50 16.4
5.40 68.2
7.10 64.2
8.30 39.8
3.60 12.6
5.50 73.2
7.20 69.4
8.40 34.4
3.70 9.0
5.60 77.6
7.30 74.0
8.50 29.4
3.80 5.8
5.70 81.2
7.40 78.2
8.60 24.4
3.90 2.8
5.80 84.6
7.50 82.2
8.70 20.6
4.00 0.2
5.90 87.4
7.60 85.6
8.80 17.0
7.70 88.4
8.90 14.0
7.80 90.6
9.00 11.4
7.90 92.2 8.00 93.4
BUFFERS 08 - 13 Buffer F: pH 8.0 - 9.10
Buffer G : pH 9.2 - 10.80
Buffer H : pH 9.60 - 11.00
Buffer I : pH 10.90 - 12.00
100 mL 0.025 M Na2B4O7.10H2O (borax) + mls of 0.1 M HCl.
100 mL 0.025 M Na2B4O7.10H2O (borax) + mls of 0.1 M NaOH.
100 mL 0.05 M NaHCO3 + mls of 0.1 M NaOH.
100 mL 0.05 M 50 mL 0.2 M KCl + Na2HPO4 + mls of 0.1 volume indicated (in mL) M NaOH. 0.2 M NaOH.
pH
pH
pH
mls of 0.1M HCl added pH
mls of 0.1M NaOH added
mls of 0.1M NaOH added
mls of 0.1M NaOH added
Buffer J : pH 12.00 - 13.00
pH
mls of 0.2M NaOH added
8.00 41.0
9.20 1.8
9.60 10.0
10.90 6.6
12.00 12.0
8.10 39.4
9.30 7.2
9.70 12.4
11.00 8.2
12.10 16.0
8.20 37.6
9.40 12.4
9.80 15.2
11.10 10.2
12.20 20.4
8.30 35.4
9.50 17.6
9.90 18.2
11.20 12.6
12.30 25.6
8.40 33.2
9.60 22.2
10.00 21.4
11.30 15.2
12.40 32.4
8.50 30.4
9.70 26.2
10.10 24.4
11.40 18.2
12.50 40.8
8.60 27.0
9.80 30.0
10.20 27.6
11.50 22.2
12.60 51.2
8.70 23.2
9.90 33.4
10.30 30.4
11.60 27.0
12.70 64.4
8.80 19.2
10.00 36.6
10.40 33.0
11.70 32.4
12.80 82.4
8.90 14.2
10.10 39.0
10.50 35.6
11.80 38.8
12.90 106.0
9.00 9.2
10.20 41.0
10.60 38.2
11.90 46.0
13.00 132.0
9.10 4.0
10.30 42.6
10.70 40.4
12.00 53.8
10.40 44.2
10.80 42.4
10.50 45.4
10.90 44.0
10.60 46.6
11.00 45.4
10.70 47.6 10.80 48.5
Acetate buffer solutions pH 3 - 6 ³ Make up the following solutions (1) 0.1M acetic acid (2) 0.1M sodium acetate (tri-hydrate) (13.6g / l) Mix in the following proportions to get the required ph
ph
Vol. of 0.1M acetic acid
Vol. of 0.1M sodium acetate
3
982.3 mls
17.7 mls
4
847.0 mls
153.0 mls
5
357.0 mls
643.0 mls
6
52.2 mls
947.8 mls
Acetate buffer solutions pH 3.6 - 5.6 Make up the following solutions (1) 0.1M acetic acid (2) 0.1M sodium acetate (tri-hydrate) (13.6g / l) Mix in the following proportions to get the required ph [Pearse 1980]
ph
Vol. of 0.1M acetic acid
Vol. of 0.1M sodium acetate
3.6
185 mls
15 mls
3.8
176 mls
24 mls
4.0
164 mls
36 mls
4.2
147 mls
53 mls
4.4
126 mls
74 mls
4.6
102 mls
98 mls
4.8
80 mls
120 mls
5.0
59 mls
141 mls
5.2
42 mls
158 mls
5.4
29 mls
171 mls
5.6
19 mls
181 mls
Phosphate buffer solutions ph 5.8 - 8.0 Make up the following solutions 5 (1) 0.2M KH2PO4 (g/ l) (2) 0.2M NaOH Add the vol. of 0.2M NaOH in table to 50 mls of 0.2M KH2PO4 and dilute to 200 mls. ph
Vol. of Naoh
ph
Vol. of NaOH
5.8
3.72 mls
7.0
29.63 mls
6.0
5.70 mls
7.2
35.00 mls
6.2
8.60 mls
7.4
39.50 mls
6.4
12.60 mls
7.6
42.80 mls
6.6
17.80 mls
7.8
45.20 mls
6.8
23.65 mls
8.0
46.80 mls
Addition of acid or base to a salt pH 3 - 11 Here, the primary salt is a solid and is weighed out in grams. A measured amount of 0.1M HCl or NaOH is added and made up to 1 liter to give the required ph. 4
pH
Salt mixture Dilute each mixture to 1 liter solution with distilled water
3
10.21g potassium hydrogen phthalate and 223ml of 0.10M HCl
4
10.21g potassium hydrogen phthalate and 1ml of 0.10M HCl
5
10.21g potassium hydrogen phthalate and 226ml of 0.10M NaOH
6
6.81g potassium dihydrogen phosphate and 56ml of 0.10M NaOH
7
6.81g potassium dihydrogen phosphate and 291ml of 0.10M NaOH
8
6.81g potassium dihydrogen phosphate and 467ml of 0.10M NaOH
9
4.77g sodium tetraborate and 46ml of 0.10M HCl
10 4.77g sodium tetraborate and 183ml of 0.10M NaOH 11 2.10g sodium bicarbonate and 227ml of 0.10M NaOH
1. The Physical and Theoretical Laboratory, Oxford University. 2. "Electrolyte solutions" Robinson, R. A., and Stokes, R. H., 2nd ed., rev. London, Butterworths, 1968. 3. "Practical chemistry" J. Lambert and T.A. Muir, 3rd. Ed. Heineman, London. 4. pdf file, www.bc.ca/bcsc/resources/ (Canadian Teachers Federation). 5. "Determination of hydrogen Ions" Clark and Lubs, Williams and Wilkins, Baltimore, 1928.