Buffer capacity of a buffer is given as two units for a change in pH b...
Buffer capacity is denoted by ? = number of moles of acid or base added to one litre of the buffer by a change in pH. Here the change in pH is given as 1, and the buffer capacity is given as 2, therefore, by substituting, we get that 2 moles of acid or base are added in one litre of the solution.
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Buffer capacity of a buffer is given as two units for a change in pH b...
Understanding Buffer Capacity
Buffer capacity is a measure of the ability of a buffer solution to resist changes in pH when an acid or base is added. It is defined as the amount of acid or base that can be added to a solution without causing a significant change in pH.
Definition of Buffer Capacity
- The buffer capacity (β) is quantitatively expressed as the change in pH (ΔpH) per unit of acid or base added (Δ[H⁺] or Δ[OH⁻]).
- In this case, a buffer capacity of 2 units indicates that for every 1 unit change in pH, 2 moles of acid or base can be added to the solution.
Calculating Moles Added
- If we consider a buffer capacity of 2, it means that to change the pH by 1 unit, 2 moles of either acid or base can be added per liter of solution.
- Therefore, if the change in pH is 1 unit, the effective amount of acid or base that can be added is given by:
- Buffer capacity (β) = moles of acid/base added (n) / change in pH (ΔpH)
- Rearranging gives: n = β × ΔpH
Final Calculation
- Substituting the values:
- n = 2 moles/unit × 1 unit = 2 moles
- Hence, when 2 moles of acid or base are added to one liter of the solution, the pH changes by 1 unit.
Conclusion
- The correct answer is option 'A', which states that 2 moles of acid or base can be added to the buffer solution to change the pH by 1 unit. Understanding this principle is crucial for applications in chemistry and biology, particularly in fields like biochemistry and medicine.