A buffer is made by dissolving H3PO4 and NaH2PO4 in water.
1. Write an equation that shows how this buffer neutralizes added acid.
Express your answer as a chemical equation. Identify all of the phases in your answer.
2. Write an equation that shows how this buffer neutralizes added base.
Express your answer as a chemical equation. Identify all of the phases in your answer.
To write the chemical equations for the neutralization of added acid and base by the buffer solution made from H3PO4 and NaH2PO4, we need to understand the dissociation of these compounds in water.
First, let's look at the dissociation of H3PO4, which is a weak acid:
H3PO4 (l) ⇌ H+ (aq) + H2PO4- (aq)
Next, let's consider the dissociation of NaH2PO4, which is a salt:
NaH2PO4 (s) → Na+ (aq) + H2PO4- (aq)
Now, let's proceed with the chemical equations for the neutralization of added acid and base by the buffer solution.
1. Neutralization of added acid with the buffer:
In this case, we'll assume that hydrochloric acid (HCl) is added as an example.
HCl (aq) + H2PO4- (aq) → H3PO4 (l) + Cl- (aq)
The added acid, HCl, reacts with the H2PO4- ion from the buffer, resulting in the formation of H3PO4 and Cl- ions.
2. Neutralization of added base with the buffer:
In this case, we'll consider sodium hydroxide (NaOH) as the added base.
NaOH (aq) + H3PO4 (l) → H2PO4- (aq) + H2O (l) + Na+ (aq)
The added base, NaOH, reacts with the weak acid, H3PO4, from the buffer. The products of this reaction are H2PO4- (dihydrogen phosphate ion), water, and Na+ (sodium ion).
Therefore, the chemical equations for the neutralization of added acid and base with the buffer made from H3PO4 and NaH2PO4 are:
1. Neutralization of added acid: HCl (aq) + H2PO4- (aq) → H3PO4 (l) + Cl- (aq)
2. Neutralization of added base: NaOH (aq) + H3PO4 (l) → H2PO4- (aq) + H2O (l) + Na+ (aq)
In these equations, (l) represents the liquid phase, (aq) indicates aqueous or dissolved in water, and (s) denotes solid.