1. What is Concentration of Acid in Acidic Buffer?

Definition: This calculator determines the concentration of acid needed in a buffer solution using Henderson's equation, based on salt concentration, pH, and pK_a.

Purpose: It helps chemists and biochemists prepare buffer solutions with specific pH values for experiments and industrial processes.

2. How Does the Calculator Work?

The calculator uses Henderson's equation:

Where:

• \( C_{acid} \) — Concentration of acid (mol/m³)
• \( C_{salt} \) — Concentration of salt (mol/m³)
• \( pH \) — Negative log of hydronium concentration
• \( pK_a \) — Negative log of acid ionization constant

Explanation: The equation relates the concentrations of acid and salt in a buffer solution to the pH and the acid's dissociation constant.

3. Importance of Buffer Calculations

Details: Accurate buffer preparation is crucial for maintaining stable pH in chemical reactions, biological systems, and industrial processes.

4. Using the Calculator

Tips: Enter the salt concentration (mol/m³), desired pH (0-14), and pK_a of the acid. All values must be valid (salt > 0, 0 ≤ pH ≤ 14, pK_a ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What is Henderson's equation used for?
A: It's used to calculate the pH of buffer solutions or to determine the ratio of acid to conjugate base needed for a specific pH.

Q2: What's a typical pK_a value for common acids?
A: Acetic acid (4.76), phosphoric acid (2.15, 7.20, 12.35 for its three protons), and citric acid (3.13, 4.76, 6.40).

Q3: When would I need to calculate acid concentration?
A: When preparing buffer solutions for laboratory experiments, pharmaceutical formulations, or biochemical assays.

Q4: What units should I use for concentration?
A: The calculator uses mol/m³, but you can convert from mol/L (M) by multiplying by 1000 (1 M = 1000 mol/m³).

Q5: How accurate is this calculation?
A: It provides theoretical values; actual preparation may require fine-tuning based on experimental conditions.