Because solution pH is a measurement of either [H3O+] or [-OH] concentration, the acidic or
basic nature of the acids and bases used in this experiment can be ascertained by inspecting
just the density (electrostatic) potentials from the products (which contain either H3O+ or –
OH). Using this data, classify the starting materials (HCl, CH3COOH, NH3, NaOH) as acids
or bases and as strong or weak electrolytes. Provide an explanation for each classification.
To classify the starting materials as acids or bases and as strong or weak electrolytes, we need to consider their behavior in water.
Acids are substances that release hydrogen ions (H+) in water. The greater the concentration of hydrogen ions, the stronger the acid. Bases, on the other hand, release hydroxide ions (OH-) in water. The greater the concentration of hydroxide ions, the stronger the base.
Strong electrolytes completely dissociate in water, producing a high concentration of ions. Weak electrolytes only partially dissociate, resulting in a lower concentration of ions.
Let's examine each of the starting materials:
1. HCl: HCl is hydrochloric acid. When it dissolves in water, it ionizes completely, producing a high concentration of H+ ions. Therefore, HCl is a strong acid and a strong electrolyte.
2. CH3COOH: CH3COOH is acetic acid. It partially ionizes in water, producing a low concentration of H+ ions. Therefore, CH3COOH is a weak acid and a weak electrolyte.
3. NH3: NH3 is ammonia. In water, it reacts with water to form ammonium ions (NH4+) and hydroxide ions (OH-). However, the concentration of hydroxide ions produced is relatively low, so NH3 is considered a weak base and a weak electrolyte.
4. NaOH: NaOH is sodium hydroxide. It completely dissociates in water, producing a high concentration of OH- ions. Therefore, NaOH is a strong base and a strong electrolyte.
In summary:
- HCl is a strong acid and a strong electrolyte.
- CH3COOH is a weak acid and a weak electrolyte.
- NH3 is a weak base and a weak electrolyte.
- NaOH is a strong base and a strong electrolyte.
By inspecting the density potentials of the products, we can observe the presence of significant concentrations of either H3O+ or OH- ions, which allows us to classify the starting materials as acids or bases and as strong or weak electrolytes.