Understanding the Concepts
* Normality (N): Normality is a measure of concentration that expresses the number of equivalents of a solute per liter of solution. For NaOH, one mole of NaOH contains one equivalent of OH- ions.
* pH: pH is a measure of the acidity or alkalinity of a solution. It is calculated as:
pH = -log[H+]
where [H+] is the concentration of hydrogen ions.
* pOH: Similar to pH, pOH is a measure of hydroxide ion concentration. It is calculated as:
pOH = -log[OH-]
* Relationship between pH and pOH: In aqueous solutions, the following relationship holds:
pH + pOH = 14
Calculations
1. NaOH is a strong base: This means it dissociates completely in water.
NaOH(aq) → Na+(aq) + OH-(aq)
2. Concentration of OH- ions: Since the normality of NaOH is 0.1 N, the concentration of OH- ions is also 0.1 M (because 1 mole of NaOH contains 1 equivalent of OH- ions).
3. Calculate pOH:
pOH = -log[OH-] = -log(0.1) = 1
4. Calculate pH:
pH + pOH = 14
pH = 14 - pOH = 14 - 1 = 13
Therefore, the pH of a 0.1 N NaOH solution is 13.
