Explain the ionization of water and calculate the H3O+ concentration at 50°C.

7.1.1. The ionization of water is ENDOTHERMIC.
As the temperature increases from $25 \text{ °C}$ to $50 \text{ °C}$, the value of $K_w$ increases from $1.00 \times 10^{-14}$ to $5.48 \times 10^{-14}$. An increase in the equilibrium constant with increasing temperature indicates that the forward reaction (ionization) is favored by higher temperatures, which is characteristic of an endothermic process.

7.1.2.

7.2.1. Water acts as an acid (donates a proton to $\text{HCO}_3^-$):

7.2.2. Water acts as a base (accepts a proton from $\text{HCO}_3^-$):

7.3.1. An electrolyte is a substance that, when dissolved in a solvent (typically water), produces ions and is therefore capable of conducting electricity.

7.3.2. The most effective electrolyte is $\text{H}_2\text{C}_2\text{O}_4$.
The reason is that $\text{H}_2\text{C}_2\text{O}_4$ has the largest $K_a$ value ($6.0 \times 10^{-2}$) among the given acids. A larger $K_a$ value indicates a stronger acid, meaning it ionizes to a greater extent in solution, producing a higher concentration of ions and thus making it a more effective electrolyte.