How does NaCl react with HCl?

Learn everything related to the reaction of sodium chloride with hydrochloric acid in this article with chemical reactions and their applications.

Introduction:

Sodium chloride NaCl also called table salt is most probably the most common salt on our planet Earth. It has a silvery-white appearance and a crystal lattice structure in its molecule. Both sodium ions (Na⁺) and chloride ions (Cl⁻) in this lattice are held together by ionic bonds and this arrangement makes it a very soluble salt in water.

It is worth mentioning that NaCl doesn’t go through any chemical change when dissolved in water but rather embraces a physical change. A liter of water may dissolve around 350–390 grams of NaCl putting it in the salts category with high water solubility. It is commonly used in the seasoning of food and during various other industrial processes.

Hydrogen chloride HCl is a very corrosive acid with high oxidative characteristics and a strong acidic nature. When introduced to water, it completely dissociates into its respective ions i.e., hydrogen ions (H⁺) and chloride ions (Cl⁻) making the solution very acidic (near to 0 pH value). It finds many industrial uses as well in different sectors.

The Reaction of sodium chloride with hydrochloric acid

When these two are allowed to react with each other, no significant reaction can be observed leading to chemical changes to both NaCl and reaction participants. The reason behind this is that NaCl is a neutral salt formed by the reaction of a strong base and a strong acid (sodium hydroxide and hydrochloric acid).

Unlike some of the neutral salts, this one doesn’t react with an acid and focuses just on making ions. As a result, no significant chemical change in NaCl is recorded during its exposure to HCl. The high reactivity of HCl ions will not stop sodium from converting itself into its ions. These ions just stay in the solution without altering the chemical stability of sodium chloride.

You will just observe NaCl being dissolved in the aqueous solution of HCl (if diluted with water) but no actual chemical reaction is happening between the two as sodium chloride will undergo a physical change rather than a chemical change (as explained above).

But wait, a Few Things Do happen:

The reaction appears to be not happening between the two but there are some changes in the solution which will occur due to the concentration of acid used in this reaction. We know that both sodium chloride with hydrochloric acid readily converts themselves in their respective ions but when concentrated HCl acid is added to table salt, a phenomenon called the common ion effect happens for the Cl⁻ ions.

The phenomenon of common ions happens in a solution containing a weak electrolyte and a salt of that specific weak electrolyte present in the solution. The addition of more salt in this electrolyte makes common ions in that specific solution (in this case Cl⁻ ions) and brings observable impacts on the properties of the reactant. These “impacts” include a shift in equilibrium between the ions, suppression of Ionization of weak electrolytes, and most importantly, a decrease in the solubility of salt in the solution.

This is exactly what you will observe in the above reaction of sodium chloride with hydrochloric (concentrated aqueous state) where sodium salt will become less soluble in this solution and will appear whiter and observable in the solution. It should be noted that the common ion effect happens usually for weak electrolytes but in this case, both are strong electrolytes with high reactivity. So, these elements in the solution have special criteria for the common ion effect.

The reaction between NaCl and HCl has no direct applications in the current industry. However, in some regions, their solution is used for the production of chlorine by carrying out electrolysis. As the common ion between the two is chlorine, carrying out electrolysis of brine yields chlorine at the anode where HCl is used to maintain the pH of the solution.

Conclusion:

When sodium chloride with hydrochloric acid is allowed to react with each other, no significant reaction takes place. Both give away strong electrolytes and they dissociate to create their ions but don’t react with each other. The only observation will be the decreased solubility of sodium chloride salt in the solution due to the common ion effect happening between the two reactants.