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0.40 M lactate ion C3H5O3^- pH 8.728 Kb

by 영원파란 2020. 11. 29.

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0.40 M lactate ion C3H5O3^- pH 8.728 Kb

 

 

The lactate ion, C3H5O3^- is a weak base.

A 0.40 M solution has a pH of 8.728.

a. Calculate the Kb of the lactate ion.

b. Calculate the Ka for lactic acid, HC3H5O3.

 

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C3H5O3^-(aq) + H2O(l) HC3H5O3(aq) + OH^-(aq)

Kh = Kb = (x) (x) / (0.40-x)

( 참고 https://ywpop.tistory.com/4294 )

 

 

 

pOH = 14.00 8.728 = 5.272

( 참고 https://ywpop.tistory.com/2706 )

 

pOH = -log[OH^-] = 5.272

[OH^-] = 10^(-5.272) M = x

 

 

 

 

a. Calculate the Kb of the lactate ion.

 

Kb = (10^(-5.272))^2 / [ 0.40 - (10^(-5.272)) ]

= 7.14×10^(-11)

 

 

 

 

b. Calculate the Ka for lactic acid, HC3H5O3.

 

Ka = Kw / Kb

( 참고 https://ywpop.tistory.com/2937 )

 

= (10^(-14)) / (7.14×10^(-11))

= 0.000140

= 1.40×10^(-4)

 

 

 

 

[키워드] 젖산 이온의 Kb 기준문서, 젖산의 Ka 기준문서

 

 

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