Question

Which of the following combinations produces a buffer system that allows maintaining pH = 7.4? (Use the pKa). Indicates if any mixture does not form a buffer system, and explains why to.

a. A mixture of 200 mL of 0.200 M HCl with 200 mL of 0.200 M NaOH.

b. A mixture of 200 mL 0.200 M with 200 mL of 0.200 M

c. A mixture of 200 mL 0.200 M with 200 mL of 0.200 M

d. A mixture of 200 mL 0.200 M with 200 mL of 0.200 M

NaH2PO4 Na3PO4 NaH2PO4 Na2HPO4 Constantes ácidas de disociación a 25°C Fórmula 0 K2 3.2 x 10-12 4698 10-11 1.73 x 105 4.02 x 10-7 6.32 x 108 4.62 × 10-7 3.21 x 10-3 4.5 x 10-13 trans-HOOCCH: CHCOOH 3 cis-HOOCCH: CHCOOH HOOCCHOHCH2COOH HOOCCH2COOH 5.9 x 10-7 8.00 × 10-6 2.01 x 10-6 1 0 0 5 3.91 x 106 5.42 x 10 4 5 x 10-9 HOOCCH2CH2COOH 2.31 x 106 1.02 x 102 6.6 x 10-8 4.31 × 10-5 HOoC(CHOH) COOH Fórmula 3 Cl,CCOOH eno Ion anilinio Ion dimetilamonio HOC2HANH 0 1.18 × 10-10 0 Peróxido de hidrógeno Sulfuro de hidrógeno 1.3 x 10-14 Nota: la mayor parte de los datos son para fuerza iónica cero. Fuente: De A. E. Martell y R. M. Smith, Critical Stability Constants, Vol. 1-6, Plenum Press, Nueva York, 1974-1989

Answer 1

Incorrect options:

a) A strong acid and a strong base do not form a buffer.

b) The buffer formed by this pair is pH = 2.1.

c) They are not a conjugate base acid pair.

d) They are two salts, they are not a conjugate base acid pair.

None of the above mixtures forms a buffer system of pH = 7.4.

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