Добавил:

fench Опубликованный материал нарушает ваши авторские права? Сообщите нам.

Вуз:

Казанский национальный исследовательский технологический университет

Предмет:

Химия

Файл:

Lange's Handbook of Chemistry (15th Edition) / 63847 8.pdf

Скачиваний:

152

Добавлен:

15.08.2013

Размер:

1.02 Mб

Скачать

☆

<<< < Предыдущая 1 2 3 4 56 / 116 7 8 9 10 11 > Следующая >>>

8.106

SECTION 8

TABLE 8.15 Compositions of Standard pH Buffer Solutions [National Bureau of Standards (U.S.)]

Air weight of material per liter of buffer solution.

		Standard			Weight, g

KH 3 (C 2O		4 )2 · 2H 2O, 0.05 M			12.61
Potassium hydrogen tartrate, about 0.034				M	Saturated at 25	C
Potassium hydrogen phthalate, 0.05				M	10.12
Phosphate:
KH 2PO 4 , 0.025 M					3.39
Na	2HPO	4 , 0.025 M			3.53
Phosphate:
KH	2PO	4 , 0.008665	M		1.179
Na	2HPO	4 , 0.03032	M		4.30
Na 2B	4 O 7 · 10H 2O, 0.01		M		3.80
Carbonate:
NaHCO		3 , 0.025 M			2.10
Na	2CO	3 , 0.025 M			2.65
Ca(OH)	2, about 0.0203		M		Saturated at 25	C

The buffer values for the NBS reference pH buffer solutions are given below:

					0.025	M	0.0087	M				0.025	M
		0.05	M	0.05 M	KH 2PO 4 ,		KH 2PO	4 ,				NaHCO	3 ,
	KH	KH	2	KH	0.25	M	0.0302	M	0.01	M		0.025	M
Buffer solution	tartrate	citrate		phthalate	Na 2HPO	4	Na 2HPO	4	Na 2B	4 O	7	Na 2CO	3
Buffer value	0.027	0.034		0.016	0.029		0.016	0.020			0.029

For the secondary pH reference standards, the buffer value is 0.070 for potassium tetroxalate and
0.09 for calcium hydroxide.
To prepare the standard pH buffer solutions recommended by the National Bureau of Standards
(U.S.), the indicated weights of the pure materials in Table 8.15 should be dissolved in water of
speciﬁc conductivity not greater than 5 micromhos. The tartrate, phthalate, and phosphates can be
dried for 2 h at 100	C before use. Potassium tetroxalate and calcium hydroxide need not be dried.

Fresh-looking crystals of borax should be used. Before use, excess solid potassium hydrogen tartrate and calcium hydroxide must be removed. Buffer solutions pH 6 or above should be stored in plastic containers and should be protected from carbon doxide with soda-lime traps. The solutions should

be replaced within 2 to 3 weeks, or sooner if formation of mold is noticed. A crystal of thymol may be added as a preservative.

8.3.2Standards for pH Measurement of Blood and Biological Media

Blood is a well-buffered medium. In addition to the NBS phosphate standard of 0.025				M	(pH s
6.480 at 38	C), another reference solution containing the same salts, but in the molal ratio 1 : 4, has
an ionic strength of 0.13. It is prepared by dissolving 1.360 g of KH				2PO 4 and 5.677 g of Na	2HPO	4
(air weights) in carbon dioxide-free water to make 1 liter of solution. The pH				s is 7.416 0.004 at
37.5 and 38	C.
The compositions and pH		s values of	tris (hydroxymethyl)aminomethane, covering the pH range
7.0 to 8.9, are listed in Table 8.16.

							ELECTROLYTES, EMF, AND CHEMICAL EQUILIBRIUM												8.107
TABLE 8.16			Composition and pH Values of Buffer Solutions
Values based on the conventional activity pH scale as deﬁned by the National Bureau of Standards (U.S.) and																		55: 197 (1955)
pertain to a temperature of 25							C [Ref: Bower and Bates,				J. Research Natl. Bur. Standards (U.S.),							55: 197 (1955)
and Bates and Bower,						Anal. Chem.,		28: 1322 (1956)]. Buffer value is denoted by column headed										.

25 ml 0.2			M	KCl				50 ml 0.1		M	KH Phthalate			50 ml 0.1		M	KH Phthalate
x ml 0.2			M	HCl,				x ml 0.1 M				HCl,			x ml 0.1		M	NaOH,
Diluted to 100 ml								Diluted to 100 ml							Diluted to 100 ml

pH			x					pH			x			pH			x

1.00		67.0					0.31	2.20		49.5				4.20		3.0		0.017
1.20		42.5					0.34	2.40		42.2			0.036	4.40	6.6			0.020
1.40		26.6					0.19	2.60		35.4			0.033	4.60	11.1			0.025
1.60		16.2					0.077	2.80		28.9			0.032	4.80	16.5			0.029
1.80		10.2					0.049	3.00		22.3			0.030	5.00	22.6			0.031
2.00		6.5					0.030	3.20		15.7			0.026	5.20	28.8			0.030
2.20		3.9					0.022	3.40		10.4			0.023	5.40		34.1			0.025
								3.60			6.3		0.018	5.60		38.8			0.020
								3.80			2.9		0.015	5.80		42.3			0.015

								50 ml 0.1		M Tris		(hydroxy-
								methyl)aminomethane							50 ml of a Mixture
									x ml 0.1		M	HCl,		0.1 M		with Respect to
50 ml 0.1			M	KH		2PO 4		Diluted to 100 ml						Both KCl and H				3 BO	3
x ml 0.1			M		NaOH,			pH/ t 0.028							x ml 0.1		M	NaOH,
Diluted to 100 ml										I 0.001		x			Diluted to 100 ml

pH			x					pH			x			pH			x

5.80		3.6						7.00		46.6				8.00		3.9
6.00		5.6					0.010	7.20		44.7			0.012	8.20	6.0			0.011
6.20		8.1					0.015	7.40		42.0			0.015	8.40	8.6			0.015
6.40		11.6					0.021	7.60		38.5			0.018	8.60	11.8			0.018
6.60		16.4					0.027	7.80		34.5			0.023	8.80	15.8			0.022
6.80		22.4					0.033	8.00		29.2			0.029	9.00	20.8			0.027
7.00		29.1					0.031	8.20		22.9			0.031	9.20	26.4			0.029
7.20		34.7					0.025	8.40		17.2			0.026	9.40	32.1			0.027
7.40		39.1					0.020	8.60		12.4			0.022	9.60	36.9			0.022
7.60		42.4					0.013	8.80		8.5			0.016	9.80	40.6			0.016
7.80		44.5					0.009	9.00		5.7				10.00	43.7			0.014
8.00		46.1												10.20		46.2

50 ml 0.025			M		Borax			50 ml 0.025			M	Borax		50 ml 0.05			M	NaHCO	3
x ml 0.1				M	HCl,			x ml 0.1			M	NaOH,			x ml 0.1		M	NaOH,
Diluted to 100 ml								Diluted to 100 ml							Diluted to 100 ml
pH/ t 0.008								pH/ t 0.008							pH/ t 0.009
	I 0.025							I 0.001(25				x)			I 0.001(25			2x)

pH			x					pH			x			pH			x

8.00		20.5						9.20		0.9				9.60		5.0
8.20		19.7					0.010	9.40		3.6			0.026	9.80	6.2			0.014
8.40		16.6					0.012	9.60		11.1			0.022	10.00	10.7			0.016
8.60		13.5					0.018	9.80		15.0			0.018	10.20	13.8			0.015
8.80		9.4					0.023	10.00		18.3			0.014	10.40	16.5			0.013

8.108											SECTION	8
TABLE 8.16		Composition and pH						Values of Buffer Solutions (							Continued	)

50 ml 0.025				M	Borax				50 ml 0.025				M	Borax			50 ml 0.05			M	NaHCO		3
x ml 0.1				M	HCl,				x ml 0.1				M	NaOH,				x ml 0.1			M	NaOH,
Diluted to 100 ml										Diluted to 100 ml								Diluted to 100 ml
pH/ t 0.008									pH/ t 0.008									pH/ t 0.009
	I 0.025								I 0.001(25					x)				I 0.001(25				2x)

pH		x							pH			x					pH			x

9.00		4.6				0.026			10.20		20.5				0.009	10.60		19.1				0.012
9.10		2.0							10.40		22.1				0.007	10.80				21.2			0.009
									10.60		23.3				0.005	11.00				22.7

		50 ml 0.05					M	Na 2HPO	4							25 ml 0.2		M	KCl
		x ml 0.1					M	NaOH,									x ml 0.2	M	NaOH,
			Diluted to 100 ml														Diluted to 100 ml
		pH/ t 0.025														pH/ t 0.033
		I 0.001(77						2x)								I 0.001(50			2x)

pH							x								pH			x

11.00					4.1				0.009					12.00			6.0				0.028
11.20					6.3				0.012					12.20			10.2					0.048
11.40					9.1				0.017					12.40			16.2					0.076
11.60					13.5				0.026					12.60			25.6					0.12
11.80					19.4				0.034					12.80			41.2					0.21
11.90					23.0				0.037					13.00			66.0				0.30

The phosphate-succinate system gives the values of pH			s	shown below:

	Molality	Molality	pH s	(pH		s / t )
	KH PO2	4 Na HC H 2O 6 5 7	pH s	(pH		s / t )

		0.005	6.251	0.000	86	deg	1
		0.005	6.251	0.000	86	deg
		0.010	6.197	0.000	71
		0.015	6.162
		0.020	6.131
		0.025	6.109	0.000	4

ELECTROLYTES, EMF, AND CHEMICAL EQUILIBRIUM									8.109
TABLE 8.17	Standard Reference Values			for thepH*Measurements		of
	Acidity in 50 Weight Percent Methanol-Water

	0.02 m		HOAc,				0.02 m	KH 2PO 4 ,
Temperature,	0.02 m	NaOAc,		0.02 m	NaHSuc,		0.02 m	Na	2HPO 4 ,
C	0.02	m	NaCl	0.02 m	NaCl		0.02	m	NaCl

10	5.560			5.806			7.937
15	5.549			5.786			7.916
20	5.543			5.770			7.898
25	5.540			5.757			7.884
30	5.540			5.748			7.872
35	5.543			5.743			7.863
40	5.550			5.741			7.858

	OAc		acetate	Suc	succinate
Reference:	R. G. Bates,		Anal Chem.,	40(6):35A (1968).

TABLE 8.18	pH* Values for Buffer Solutions in Alcohol-Water
	Solvents at 25			C
Liquid-junction potential not included.

Solvent
Composition
(weight per	0.01	M H	2C 2O	4 ,	0.01	M	H 2Suc,	0.01	M	HSal,
cent alcohol)	0.01 M	NH	4 HC	2O 4	0.01	M	LiHSuc	0.01	M	NaSal
		Methanol-Water Solvents
0		2.15				4.12
0		2.15				4.12
10		2.19				4.30
20		2.25				4.48
30		2.30			4.67
40		2.38				4.87
50		2.47				5.07
60		2.58				5.30
70		2.76				5.57
80		3.13			6.01
90		3.73			6.73
92		3.90				6.92
94		4.10				7.13
96		4.39				7.43
98		4.84				7.89
99		5.20				8.23
100		5.79				8.75		7.53
		Ethanol-Water Solvents
0		2.15				4.12
0		2.15				4.12
30		2.32				4.70
50		2.51				5.07
71.9		2.98				5.71
100								8.32

Suc succinate

Sal salicylate

<<< < Предыдущая 1 2 3 4 56 / 116 7 8 9 10 11 > Следующая >>>

Соседние файлы в папке Lange's Handbook of Chemistry (15th Edition)

#
15.08.2013389.34 Кб14063847 3.pdf
#
15.08.2013493.08 Кб15163847 4.pdf
#
15.08.2013909.2 Кб19163847 5.pdf
#
15.08.2013756.49 Кб13763847 6.pdf
#
15.08.20131.51 Mб13763847 7.pdf
#
15.08.20131.02 Mб15263847 8.pdf
#
15.08.201354.75 Кб13463847 9.pdf
#
15.08.201353.14 Кб12663847 pref.pdf