Aim: To prepare and submit 30ml of Magnesium hydroxide mixture BP
Hydroxide IP Synonym: Milk of Magnesia/Cream of Magnesia.
Apparatus:
- Beaker
- Glass rod
- Glass funnel
- Measuring cylinder
Formula:
| Ingredients | Official Formula | Working Formula |
|---|---|---|
| Magnesium sulphate | 47.5g | 14.25g |
| Sodium hydroxide | 15g | 0.45g |
| Light Magnesium oxide | 52.5g | 1.6g |
| Citric acid | 1g | 0.03g |
| Chloroform | 2.5ml | 0.075ml |
| Purified Water(freshly boiled and cooled) | 1000ml | 30ml |
Principle:
Magnesium hydroxide is obtained by two chemical reactions namely hydration and precipitation.
Hydration of magnesium oxide alone results in suspension which is more like a gel which is difficult to pour. Precipitation reaction alone produce solid which settles easily.
However, when hydration along with precipitation reactions are combined, product has required viscosity and the solids haves acceptable diffusivity. Hence Magnesium sulphate is reacted with alkali hydroxide to get magnesium hydroxide precipitate. However, alkali sulphate is formed as by product as by product which produces cathartic effect. Thus repeated washing of precipitate with water is essential to remove sulphate ion.
MgO + H2O → Mg(OH)2 Hydration reaction( Gelatinous product)
NaOH + MgSO4 → Na2SO4 + Mg(OH)2 Precipitation reaction (precipitation settles easily)
Wash water is mixed with barium chloride solution and if no milky white turbidity is observed indicates absence of sulphate ion(white turbidity is due to formation of barium sulphate).
BaCl2 + SO42- → BaSO4 + 2Cl-
The preparation is alkaline in nature add to reduce its interaction with glass container, citric acid is added. Chloroform water acts as vehicle, preservative and flavor.
Procedure:
- Dissolve sodium hydroxide in sufficient water, add light magnesium oxide , mix to form smooth paste. Add water to produce to about 10ml
- Pour this in a thin stream into the solution of magnesium sulphate (in about 10ml) withstirring.
- Allow the precipitate to settle, decant the clear supernatant
- Wash the precipitate repeatedly with distilled water until removal of sulphate ion
- Once sulphate ions are removed , clear liquid is drained
- Precipitate is mixed with citric acid and chloroform, transferred to a container
- Make up the volume with water, label and dispense
Category: Antacid (Neutralizes acid in stomach, relieve heartburn) and (laxative(promotes emptying to bowels, used to combat constipation)
Dose: Antacid 2-4ml; laxative 8-16 ml
Direction: Shake well before use.
Storage: Store in a well closed blue color container in warm place protected from light (not in cool place to avoid aggregation of solids).
Report: 30ml Magnesium hydroxide mixture B.P prepared and submitted
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