Answer: a) ![HCN(aq.)+H_2O\rightleftharoons H_3O^+(aq.)+CN^-(aq.)](https://tex.z-dn.net/?f=HCN%28aq.%29%2BH_2O%5Crightleftharoons%20H_3O%5E%2B%28aq.%29%2BCN%5E-%28aq.%29)
b)
: acid
:conjugate base.
And,
: base
: conjugate acid.
c) ![HCN(aq.)+NaOH(aq)\rightleftharoons NaCN(aq.)+H_2O(l)](https://tex.z-dn.net/?f=HCN%28aq.%29%2BNaOH%28aq%29%5Crightleftharoons%20NaCN%28aq.%29%2BH_2O%28l%29)
d) ![NaCN(aq)\rightarrow Na^+(aq.)+CN^-(aq)](https://tex.z-dn.net/?f=NaCN%28aq%29%5Crightarrow%20Na%5E%2B%28aq.%29%2BCN%5E-%28aq%29)
e) ![NaCN(aq)+HCl(aq)\rightarrow NaCl(aq.)+HCN(aq)](https://tex.z-dn.net/?f=NaCN%28aq%29%2BHCl%28aq%29%5Crightarrow%20NaCl%28aq.%29%2BHCN%28aq%29)
Explanation:
a) Weak acid is defined as the acid which does not completely dissociates when dissolved in water. They have high pH. These releases
ions in their aqueous states.
The equation for the dissociation of
acid is given by:
![HCN(aq.)+H_2O\rightleftharoons H_3O^+(aq.)+CN^-(aq.)](https://tex.z-dn.net/?f=HCN%28aq.%29%2BH_2O%5Crightleftharoons%20H_3O%5E%2B%28aq.%29%2BCN%5E-%28aq.%29)
b) According to the Bronsted-Lowry conjugate acid-base theory, an acid is defined as a substance which looses donates protons and thus forming conjugate base and a base is defined as a substance which accepts protons and thus forming conjugate acid.
For the given chemical equation:
is loosing a proton, thus it is considered as an acid and after losing a proton, it forms
which is a conjugate base.
And,
is gaining a proton, thus it is considered as a base and after gaining a proton, it forms
which is a conjugate acid.
c) Neutralization reaction is a reaction in which an acid reacts with base to produce salt and water.
![HCN(aq.)+NaOH(aq)\rightarrow NaCN(aq.)+H_2O(l)](https://tex.z-dn.net/?f=HCN%28aq.%29%2BNaOH%28aq%29%5Crightarrow%20NaCN%28aq.%29%2BH_2O%28l%29)
d) The chemical equation for dissociation of
in water.
![NaCN(aq)\rightarrow Na^+(aq.)+CN^-(aq)](https://tex.z-dn.net/?f=NaCN%28aq%29%5Crightarrow%20Na%5E%2B%28aq.%29%2BCN%5E-%28aq%29)
e) The chemical equation for the reaction of
and ![HCI](https://tex.z-dn.net/?f=HCI)
![NaCN(aq)+HCl(aq)\rightarrow NaCl(aq.)+HCN(aq)](https://tex.z-dn.net/?f=NaCN%28aq%29%2BHCl%28aq%29%5Crightarrow%20NaCl%28aq.%29%2BHCN%28aq%29)