The ionization of hydrochloric in water is given below: HCl(aq) + H2O (l) <=> H3O+(aq) + Cl-(aq). Label two conjugate acid-base pairs in this ionization.

In the forward reaction, $\text{HCl}$ donates a proton ($\text{H}^+$) to $\text{H}_2\text{O}$.
Therefore, $\text{HCl}$ is the acid and $\text{H}_2\text{O}$ is the base.

When $\text{HCl}$ loses a proton, it forms $\text{Cl}^-$. So, $\text{Cl}^-$ is the conjugate base of $\text{HCl}$.
When $\text{H}_2\text{O}$ gains a proton, it forms $\text{H}_3\text{O}^+$. So, $\text{H}_3\text{O}^+$ is the conjugate acid of $\text{H}_2\text{O}$.

The two conjugate acid-base pairs are:

• $\text{HCl}$ (acid) and $\text{Cl}^-$ (conjugate base)
• $\text{H}_2\text{O}$ (base) and $\text{H}_3\text{O}^+$ (conjugate acid)

Q2. The aqueous solution of sugar does not conduct electricity. However, when sodium chloride is added to water, it conducts electricity. How will you explain this statement on the basis of ionisation and how is it affected by the concentration of sodium chloride?

Sugar is a non-electrolyte because it is a covalent compound that dissolves in water as molecules, not ions. Since there are no free mobile ions, sugar solutions do not conduct electricity.

Sodium chloride ($\text{NaCl}$) is an ionic compound and a strong electrolyte. When dissolved in water, it undergoes dissociation into free, mobile ions ($\text{Na}^+$ and $\text{Cl}^-$). These mobile ions can carry electric charge, allowing the solution to conduct electricity.

The electrical conductivity of a sodium chloride solution is directly affected by its concentration. As the concentration of sodium chloride increases, the number of $\text{Na}^+$ and $\text{Cl}^-$ ions per unit volume increases. More ions mean more charge carriers, which leads to a higher electrical conductivity. Conversely, decreasing the concentration reduces the number of ions and thus decreases conductivity.