Acetic Acid Ka Formula

Acetic Acid Dissociation Constant:

\[ K_a = 1.8 \times 10^{-5} \, \text{mol/L} \, \text{at} \, 25^\circ\text{C} \]

Dissociation Constant (K_a):

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1. What Is Acetic Acid Ka Formula?

The acetic acid dissociation constant (K_a) represents the equilibrium constant for the dissociation of acetic acid in water. It quantifies the acid's strength and its tendency to donate protons in aqueous solution.

2. How Does The Calculator Work?

The calculator uses the standard dissociation constant and acid-base equilibrium principles:

\[ K_a = 1.8 \times 10^{-5} \, \text{mol/L} \, \text{at} \, 25^\circ\text{C} \] \[ \text{CH}_3\text{COOH} \rightleftharpoons \text{CH}_3\text{COO}^- + \text{H}^+ \] \[ \text{pH} = -\log_{10}\sqrt{K_a \times C} \]

Where:

\( K_a \) — Acid dissociation constant (1.8 × 10⁻⁵ mol/L)
\( C \) — Initial concentration of acetic acid (mol/L)
Temperature — Standard value at 25°C

Explanation: The dissociation constant indicates that acetic acid is a weak acid, only partially dissociating in aqueous solution.

3. Importance Of Ka Calculation

Details: Knowing the Ka value is essential for understanding acid strength, predicting pH of solutions, calculating buffer capacities, and designing chemical processes involving acetic acid.

4. Using The Calculator

Tips: Enter temperature in °C and acetic acid concentration in mol/L. The calculator provides the standard Ka value and calculates the resulting pH of the solution.

5. Frequently Asked Questions (FAQ)

Q1: Why Is Acetic Acid Considered A Weak Acid?
A: Acetic acid has a small Ka value (1.8 × 10⁻⁵), indicating it only partially dissociates in water, making it a weak acid compared to strong acids like HCl.

Q2: How Does Temperature Affect Ka?
A: Ka values generally increase with temperature for weak acids as dissociation is endothermic, though the change is relatively small for acetic acid.

Q3: What Is The Relationship Between Ka And pKa?
A: pKa = -log₁₀(Ka). For acetic acid, pKa = -log(1.8 × 10⁻⁵) = 4.74 at 25°C.

Q4: Can Ka Be Used For Buffer Calculations?
A: Yes, Ka is fundamental for Henderson-Hasselbalch equation used in buffer pH calculations: pH = pKa + log([A⁻]/[HA]).

Q5: How Accurate Is The Standard Ka Value?
A: The value 1.8 × 10⁻⁵ mol/L is well-established experimentally and widely accepted in chemical literature for acetic acid at 25°C.