Which pairs of substances will form a buffer when mixed in equal concentrations?
You didn't list any pairs. The answer to your question, however, when you get it printed is a mixture of a weak acid and its salt or a weak base and its salt.
To determine which pairs of substances will form a buffer when mixed in equal concentrations, we need to consider two key components: a weak acid (or base) and its conjugate base (or acid). When these components are mixed in equal concentrations, they will create a buffer solution that can resist changes in pH.
Here's a step-by-step approach to finding such pairs of substances:
1. Identify a weak acid (or base): Look for compounds that can donate or accept a proton (H+) but do not completely dissociate in water. Examples include acetic acid (CH3COOH), carbonic acid (H2CO3), and ammonia (NH3).
2. Find the conjugate base (or acid) of the weak acid (or base): The conjugate base is formed by removing a proton from the weak acid (or adding a proton to the weak base). For example, the conjugate base of acetic acid (CH3COOH) is acetate ion (CH3COO-), and the conjugate acid of ammonia (NH3) is ammonium ion (NH4+).
3. Mix equal concentrations of the weak acid (or base) and its conjugate base (or acid): It is crucial to have equal concentrations of the weak acid/base and its conjugate base/acid. This ensures that the buffer maintains its pH capacity.
Examples of pairs that form a buffer solution when mixed in equal concentrations include:
- Acetic acid (CH3COOH) and sodium acetate (CH3COONa)
- Carbonic acid (H2CO3) and sodium bicarbonate (NaHCO3)
- Ammonia (NH3) and ammonium chloride (NH4Cl)
Remember, the key is to have both components (weak acid/base and its conjugate base/acid) present in equal concentrations to create an effective buffer solution.