Sodium hydroxide Stock Solution

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Stock Solution Preparation Guide – 10 M Sodium Hydroxide (NaOH) Solution

A 10 M sodium hydroxide (NaOH) stock solution is widely used for pH adjustment and alkaline reagent preparation. The molarity equals the normality for NaOH (10 M ≈ 10 N). A 10 M solution is strongly alkaline and requires careful handling due to the exothermic dissolution of NaOH pellets.

Objective

Preparation of 100 mL of 10 M NaOH stock solution.

Composition

• 10 M sodium hydroxide (NaOH) aqueous solution

Required Materials

• Sodium hydroxide pellets (NaOH solid)
• Deionized or double‑distilled water
• Analytical balance
• Beaker or Erlenmeyer flask
• Measuring cylinder or volumetric flask (100 mL)
• Glass stirring rod or magnetic stirrer
• Ice bath (optional, for heat control)
• Personal protective equipment (lab coat, gloves, goggles)

Procedure

• Step 1
  To prepare 100 mL of 10 M NaOH solution, accurately weigh **40 g** of NaOH pellets (MW = 40).
• Step 2
  Place approximately **70 mL** of deionized water in a beaker. Slowly add the pellets into the water in small portions (e.g., 4–5 pellets at a time), stirring continuously until dissolved. This reaction is highly exothermic; consider using an ice bath to control heat.
• Step 3
  Transfer the dissolved solution to a 100 mL volumetric flask or measuring cylinder. Rinse the beaker with deionized water and add rinses to the flask. Add water to adjust the final volume to **100 mL**. Mix thoroughly.
• Step 4
  There is no need to sterilize this concentrated base; microorganisms will not grow in 10 M NaOH.

Note: NaOH pellets are hygroscopic; do not expose solid to air for prolonged periods while weighing. Always label the container clearly with concentration, preparation date, and hazard warnings. Store the solution at room temperature in a tightly sealed chemical bottle.

Available Reagents