Question

Which equilibrium system has HCO3- acting as a Brønsted-Lowry base? HCO3- H+ + CO3 2- HCO3-  :  

+ HS- H2S + CO32-  HCO3-  :
+ H2S H2CO3 + HS- :  
     HCO3- + H2O H3O+ + CO32-  : 
          HCO3- + O2- CO32- + OH-

Answer 1

Answer : The equilibrium system in which
`HCO3^-` acting as a Brønsted-Lowry base is,
`HCO_3^-+H_2S\rightleftharpoons H_2CO_3+HS^-`

Explanation :

According to the Bronsted-Lowry conjugate acid-base concept, an acid is a substance that donates protons and forming conjugate base and a base is a substance that accepts protons and forming conjugate acid.

`HCO_3^-+H_2S\rightleftharpoons H_2CO_3+HS^-`

In this equilibrium system,
`HCO3^-` acting as a Brønsted-Lowry base which accepts protons and forming conjugate acid
`H_2CO_3`.

`HCO_3^-\rightleftharpoons H^++CO_3^(2-)\\\\HCO_3^-+HS^-\rightleftharpoons H_2S+CO_3^(2-)\\\\HCO_3^-+ H_2O\rightleftharpoons H_3O^++CO_3^(2-)\\\\HCO_3^-+O^(2-)\rightleftharpoons CO_3^(2-)+OH^-`

While in these equilibrium system,
`HCO3^-` acting as a Brønsted-Lowry acid which donates protons and forming conjugate base
`CO_3^(2-)`.

Hence, the equilibrium system in which
`HCO3^-` acting as a Brønsted-Lowry base is,
`HCO_3^-+H_2S\rightleftharpoons H_2CO_3+HS^-`

Answer 2

Answer is: HCO₃⁻ + H₂S → H₂CO3 + HS⁻.

According to Bronsted-Lowry theory acid are donor of protons and bases are acceptors of protons (the hydrogen cation or H⁺).

The bicarbonate anion (HCO₃⁻) is Bronsted base and it can accept proton and become conjugate acid H₂CO₃.

H₂S (hydrogen sulfide) is Bronsted-Lowry acid because it lost proton.