Question

Citric acid,HC6H7O7 and lithium propanoate,LiC3H5O2.

write the identity of the two species in each set  (strong acid/strong base/weak acid/weak base/salt/other) and explain reason. Identify  if anything in common betweenthe  two species .How are the two species in each set are related to each other?   If there is a weak acid or a weak base present writethe equation for the dissociation of the weak acid or the weak base. Then label the species in theequation as a weak acid and its conjugate base or a weak base and its conjugate acid. Also determine the Ka for the acid species (if you are dealing  with  a  weak base how could you possibly find a Ka  for  the  acid  species  in  the  equation?)Is this mixture a buffer and why?

Answer 1

Answer:

Citric Acid is the Organic Acid, It is the weak acid.

Lithium propanoate is the salt from weak acid and strong base

CH₃CH₂COOH + LiOH CH₃CH₂COOLi + H₂O

Weak acid Strong base Salt   

From these two compounds we can prepare the Buffer

Acid buffer:

Weak acid + weak acid strong base salt

That means

Citric acid + Lithium propanoate

Dissociation of Weak acid:

HOOCCH₂C(OH)(COOH)CH₂COOH HOOCCH₂C(OH)(COOH)CH₂COO^- Ka₁

HOOCCH₂C(OH)(COOH)CH₂COO^-    -OOCCH₂C(OH)(COOH)CH₂COO^- Ka₂

^-OOCCH₂C(OH)(COOH)CH₂COO^-    -OOCCH₂C(OH)(COO^-)CH₂COO^- Ka₃

Note:

Weak acids can not dissociate completely. Hence we can show the dissociation as equilibrium.

Lithium propanoate dissociation:

CH₃CH₂COOLi     CH₃CH₂COO^-  + Li⁺

Note:

Lithium propanoate is the strong base weak acid salt. Hence it can dissociate completely.