Preparation of 1M Sodium Phosphate Monobasic (NaH₂PO₄)

OVERVIEW
A 1M Sodium phosphate monobasic (also called Monosodium phosphate and Sodium dihydrogen phosphate) solution can be prepared by dissolving 119.98 g of Sodium phosphate monobasic (Na₂HPO₄, Molecular weight 119.98) in deionized water to a final volume of 1000 ml.

REQUIREMENTS

Reagents and solutions
Sodium phosphate monobasic, anhydrous (Na₂HPO₄) (Molecular weight: 119.98)
Deionized / Distilled water

Equipment and disposables
Measuring cylinder
Conical flask / Beaker
Magnetic stirrer
Spatula

COMPOSITION
1 M Sodium phosphate monobasic

OBJECTIVE
Preparation of 1000 ml of 1M Sodium phosphate monobasic solution in water from Sodium phosphate monobasic  (Na₂HPO₄)

PREPARATION:

Use personal protective equipment (lab coat, gloves, goggles, etc) for your safety and follow the guidelines of your institute.

Step 1: To prepare 1000 ml of 1M Sodium phosphate monobasic solution, weigh out 119.98 g of  Sodium phosphate monobasic (Molecular weight : 119.98). Transfer to a 2 L  beaker/conical flask. Add 800 ml of deionized/distilled water. Mix until sodium phosphate monobasic dissolves completely.

Note
Anhydrous Sodium phosphate monobasic is readily converted into hydrated forms due to its hygroscopic nature.

Tip
One can use manual shaking using a glass pipette to mix the ingredients. Magnetic stirrer makes the dissolving process easy and convenient.

Precaution
Do not dissolve in 1000 ml of deionized / Distilled water. In most cases, solution volume increases when a large amount of solute dissolves in the solvent.

Step 2: Adjust the volume to 1000 ml with deionized / Distilled water. Mix it again.

Note:
The solution will appear colorless and transparent.

Step 4: Transfer the solution to an autoclavable bottle. Sterilize the solution by autoclaving (20 minutes at 15 lb/sq.in. (psi) from 121-124°C on liquid cycle).

STORAGE
Solution can be stored at room temperature.

APPLICATIONS

• Preparation of Sodium phosphate buffer