Question

What is the pH of Sodium Carbonate (${\mathrm{Na}}_2{\mathrm{CO}}_3$)?

Answer 1

Part 1: pH

• The pH of any solution is defined as the negative log of Hydrogen ion concentration.
• Mathematically, $\mathrm{pH}=-{\log }_{10}\left[{\mathrm{H}}^{+}\right]$
• pH is used to determine the nature of the solution whether it is acidic, basic, or neutral.

Solution	pH range
Acidic	1 - 6.9
Neutral	7
Basic	7.1 - 14

Part 2: Identifying the pH of the Sodium carbonate

• The corresponding acid and base of salt can be produced by the hydrolysis of salt.
• The hydrolysis reaction can be represented as:

$\underset{\mathrm{Sodium}\mathrm{carbonate}}{{\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}\to \underset{\mathrm{Carbonic}\mathrm{acid}}{{\mathrm{H}}_2{\mathrm{CO}}_3\left(\mathrm{aq}\right)}+\underset{\mathrm{Sodium}\mathrm{hydroxide}}{2\mathrm{NaOH}\left(\mathrm{aq}\right)}$

• Therefore, Sodium carbonate is a basic salt that is formed by the neutralization of a weak hydrochloric acid by a strong base Sodiium hydroxide.
• Hence, the pH of Sodium carbonate lies in the slightly basic range.
• Hence, pH value of Sodium carbonate lies in the range of 10 to 11.