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Explain the terms (a) flocculation, (b) pH, (c) acid dissociation constant (Ka), (d) conjugate pair - Leaving Cert Chemistry - Question 8 - 2001
Question 8
Explain the terms (a) flocculation, (b) pH, (c) acid dissociation constant (Ka), (d) conjugate pair. Give the name or formula of a flocculating agent commonly used ... show full transcript
Worked Solution & Example Answer:Explain the terms (a) flocculation, (b) pH, (c) acid dissociation constant (Ka), (d) conjugate pair - Leaving Cert Chemistry - Question 8 - 2001
Step 1
(a) flocculation
Answer
Flocculation is the process by which fine particulates are agglomerated into a floc. This occurs when a flocculating agent is added to a suspension, leading to the formation of larger aggregates that settle out of the liquid. This process is crucial in water treatment, as it effectively removes suspended solids, making water clearer and reducing the load on filtration systems.
Step 2
(b) pH
Answer
pH is a measure of the hydrogen ion concentration in a solution, indicating its acidity or alkalinity on a logarithmic scale ranging from 0 to 14. A pH of 7 is neutral; values below 7 indicate acidity, while values above 7 indicate alkalinity. The pH of water is critical in various treatment processes, as it affects the solubility and availability of many chemical species.
Step 3
(c) acid dissociation constant (Ka)
Answer
The acid dissociation constant, denoted as Ka, is a quantitative measure of the strength of an acid in solution. It is defined by the equation:
K_a = rac{[H^+][A^-]}{[HA]}
where [H+] is the concentration of hydrogen ions, [A^-] is the concentration of the conjugate base, and [HA] is the concentration of the acid. A higher Ka value indicates a stronger acid, which dissociates more completely in solution.
Step 4
(d) conjugate pair
Answer
A conjugate pair consists of an acid and its corresponding base that differ by a single proton. In a reaction, when an acid donates a proton (H+), it forms its conjugate base. Conversely, the base can accept a proton to regenerate the acid. For example, in the pair ext{HA} (acid) and ext{A}^- (conjugate base), HA donates a proton to form A^-.
Step 5