Question

What is the chemical purpose of adding HCl in this step?

a) Neutralizing a base
b) Initiating a reaction
c) Increasing acidity

Answer 1

The chemical purpose of adding HCl is to increase acidity by adding H+ ions to the solution, which can neutralize bases, initiate reactions, or increase solution acidity.

Step-by-step explanation:

The addition of HCl (hydrochloric acid) to a chemical reaction typically serves the purpose of increasing acidity by introducing more H+ ions into the solution. According to the Arrhenius Theory of Acids and Bases, an Arrhenius acid such as HCl increases the concentration of H+ ions in aqueous solution. When HCl is added to water, it dissociates completely into hydrogen (H+) and chloride (Cl⁻) ions, which can have several effects:

1. Neutralizing a base: If there is a basic substance in the solution, the H+ ions from HCl can react with the OH⁻ ions from the base to form water, thereby neutralizing the base.
2. Initiating a reaction: In some reactions, the presence of excess H+ ions is necessary to proceed, making the addition of HCl a way to initiate or drive the reaction forward.
3. Increasing acidity: In cases where the desired condition is a lower pH, the addition of HCl will increase the amount of free H+ ions, resulting in increased acidity of the solution.

In the context provided, the addition of HCl is likely serving to increase the percent of acetic acid that reacts by shifting the equilibrium to favor the production of CH3 CO₂⁻ ions.