Explain which of the following reactions will occur.
a.`overset (RCOOH) underset (pK_(a)=5)` + `overset (HCO_(3)^(-) underset (pK_(a)=10.3)` `rarr`
b. `RCOOH + CO_(3)^(2-) rarr`

Explanation

The acid-base equilibrium reaction favours the side with weaker acid `(W_(A))` and weaker base `(W_(B))`. If the weaker acid is on the right side, the reaction occurs, but if the weaker acid is on the left side, the reverse reaction occurs.
a. The reaction is:
`overset (RCOOH) underset (pK_(a)=5)` + `overset (HCO_(3)^(-)) underset (pK_(a)=10)` `rarr` `overset (RCOO^(-)) underset (Weaker conjugate base (C_(B))` + `overset (H_(2)O+CO_(2)) underset (W_(A)(pK_(a)=6.4))`
b. Reaction occurs
`RCOOH + CO_(3)^(2-) rarr` `overset (RCOO^(-)) underset (WC_(B))` + `overset (HCO_(3)^(-)) underset (pK_(a)=10.3 W_(A))`
c.
this reaction occurs if any substituted phenol that has `pK_(a) gt 10.5` does not react, e.g.,
e.
f. Reaction occurs.
`PhO^(-) + `overset (H_(2)O + CO_(2)) underset pK_(a)=6.4)` `rarr` `overset (PhOH) underset (W_(A)pK_(a)=10)` + `HCO_(3)^(-)`
g. Reaction occurs. RSH is a stronger acid than `H_(2)O`, and ROH. Therefore, `RS^(-)` is a weaker base than `O^(-)H` and `RO^(-)`.
h. Reverse reaction occurs.
`overset (ROH + O^(-)H) underset (W_(A) W_(B))` `overset (RS^(-) + H_(2)O) underset _(S_(B) S_(A))`
(Alcohols are weaker acids than OH and `H_(2)O`, and `RO^(-)` is stronger base than `O^(-)H`.) However, the differences in acidities and basicities are small and all species are present in equilibrium.
i. Reverse reaction occurs.
`overset (ROH + RS^(-)) underset (W_(A) W_(B))` `RSH + RO^(-)) underset (S_(A) S_(B))`
RSH (thiols) are stronger acids than ROH, and `RO^(-)` is a stronger base than `RS^(-)`.
j. Reaction occurs. `overset (RSH + RO^(-)) underset (S_(A) S_(B))` `rarr` `overset (RS^(-) + ROH) underset (W_(B) W_(A))`