Magnesium Bicarbonate: Overview, Questions, Preparation

Magnesium bicarbonate is a highly unstable compound and a bicarbonate salt of magnesium in the solid state. The chemical formula of magnesium bicarbonate is Mg(HCO3)2. Unlike lithium, which forms a solid bicarbonate compound, magnesium is unable to do so, and hence magnesium bicarbonate only exists in aqueous or solution form.

• It is a basic compound.
• It has a pH value of around 8.3.
• It is odorless.
• It is a light, white and unstable friable mass or powder.

Its chemical name is magnesium bicarbonate, and the IUPAC name is magnesium hydrogen carbonate. In this salt, bicarbonate is the anion present while magnesium is the cation. 

1.   Molecular weight - 146.3387 g.
2.   Boiling point - 333.6 °C at 760 mmHg
3.   Monoisotopic mass - 145.97 g/mol
4.   Charge - 0 (Mg2+ and HCO3–) 
5.   Solubility - Soluble in water 0.077 g / (100 mL). Insoluble in ethanol. 

1.   Magnesium bicarbonate decomposes and forms magnesium carbonate, water and free carbon dioxide. The reaction is as follows: 

Mg(HCO3)2 → MgCO3 + H2O + CO2 

2.   Heating of magnesium bicarbonate causes temporary hardness in water, and on heating it easily decomposes back to carbonate. 

1.   It can be synthesised by treating sodium bicarbonate with magnesium acetate. The reaction is as follows:

Mg(CH3COO)2 + 2NaHCO3 → Mg(HCO3)2 + 2CH3COONa 

2.   It can also be produced by treating magnesium hydroxide with pressurised carbon dioxide. Magnesium hydroxide is also known as ‘milk of magnesia’. The reaction is as follows:

Mg(OH)2 + 2CO2 → Mg(HCO3)2 

The resultant product will be in solution form. On drying the above product, magnesium bicarbonate will decompose to produce magnesium carbonate along with carbon dioxide and water.  The reaction is as follows:

Mg + 2HCO3 → MgCO3 + CO2 + H2O 

1. Magnesium bicarbonate is shown to have many health benefits. It is beneficial to eliminate changes in blood pH and keep the value within an optimal range.
2. It acts as an antacid and decreases hyperacidity in conditions such as gastritis, hiatal hernia, peptic ulcers and reflux esophagitis.
3. It acts as an essential mineral and helps in blood regulation, protein synthesis and nerve and muscle functions.
4. It also helps in blood glucose control.
5. It is used to treat patients with renal insufficiency.
6. It is used in food additives including acidity regulators, alkali and anti-cracking and bleaching agents.

About Magnesium Bicarbonate in Class 10 

Magnesium bicarbonate is featured in the chapter ‘Acids, Bases and Salts’. The expected weightage of ‘Acids, Bases and Salts’ in Class 10 science is 3 marks. In this topic, students will learn about the nature and behaviour of acids, bases and salts. The topic mainly describes the chemical nature of acids, bases and salts and their reactions with metals, non-metals and each other.

• Synthesis of magnesium bicarbonate using sodium bicarbonate and magnesium acetate.

            Mg(CH3COO)2 + 2NaHCO3 → Mg(HCO3)2 + 2CH3COONa 

• Decomposition of magnesium bicarbonate.

            Mg(HCO3)2 → MgCO3 + H2O + CO2 

• Producing magnesium bicarbonate from milk of magnesia.

            Mg(OH)2 + 2CO2 → Mg(HCO3)2 

Q: What is the chemical formula of magnesium bicarbonate?

Q: What is the IUPAC name of magnesium bicarbonate?

Q: Which form does magnesium bicarbonate exist in?

Q: Are magnesium carbonate and magnesium bicarbonate different?

Q: How is magnesium bicarbonate commonly prepared?