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Magnesium Bicarbonate, in Chemistry, is a compound in solid stage which is an unstable compound of magnesium. It has the IUPAC name as ‘Magnesium Hydrogen Carbonate.’ The formula of Magnesium Bicarbonate is Mg (HCO3)2. This compound only exists in solutions and formed due to the action of water that contains free carbon dioxide on magnesite, dolomite limestone, dolomite as well as other magnesium carbonate. This compound causes hardness in water that is temporary; which on heating decomposes back to the carbonate state.
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Structure of Magnesium Bicarbonate
The chemical structure of Magnesium Bicarbonate is:
- It is prepared with the suspension of Magnesium Hydroxide with treatment with pressurized carbon dioxide. The formula is,
Mg (OH)2 + 2 CO2 → Mg (HCO3)2
- It is also known as bicarbonate salt of magnesium
Fig. Magnesium Bicarbonate
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Properties of Magnesium Bicarbonate
The properties of Magnesium Bicarbonate are given below:
| Mg (HCO3)2 | Magnesium Bicarbonate |
| pH | 8.3 |
| Boiling Point | 333.6 °C at 760 mmHg |
| Molar mass or Molecular Weight | 146.3387 |
| Chemical Formula | C2H2MgO6 |
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Magnesium Bicarbonate: Physical Properties
The physical properties of Magnesium Bicarbonate are tabulated below:
| Appearance | In Liquid form (only) |
| Odour | Odourless |
| Charge | +2 |
| Monoisotopic Mass | 145.97 g/mol |
| Solubility | Soluble in water to 5.7 g/100ml at 20°C |
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Magnesium Bicarbonate: Chemical Properties
- This compound – Magnesium Bicarbonate decomposes easily into carbonate, water and free carbon dioxide.
- Reaction: Mg (HCO3)2 → Mg CO3 +H2O + CO2
Uses of Magnesium Bicarbonate
- Magnesium Bicarbonate is used for treatment of patients suffering with renal insufficiency and are given cautiously in case of pregnancy and also during breastfeeding
- Used for balancing the pH Level in human body
- Used to decrease the hyperacidity when given as antacids. Given in cases like peptic ulcer diseases, Hiatal hernia and gastritis.
- Magnesium Bicarbonates are used as additives in food like alkali, anti-cracking, acidity regulators and as bleaching agents
- It is used in human bodies for protein synthesis, nerve and muscle functions, and glucose control and blood-pressure regulations.
Also Read: Carbon and Its Compounds Important Questions
Magnesium Bicarbonate: Hardness of Water
- Permanent Hardness: In water, permanent hardness is caused when Magnesium and calcium chlorides or sulphides are dissolved in water. This cannot be simply removed by just boiling water. This hard water has to be treated with washing soda for the removal of permanent hardness of water.
- Temporary Hardness: when unstable chemicals such as calcium hydrogen carbonate & Magnesium hydrogen carbonate causes are dissolved in water, temporary hardness in water is caused. It can be removed by heating the hard water. While heating, the Magnesium and calcium hydrogen carbonates gets precipitated and then they can be further separated with the help of physical procedures.
Preparation of Magnesium Bicarbonate
Magnesium Bicarbonate can be prepared using these steps:
Step 1: treating magnesium acetate with sodium bicarbonate
Mg (CH3COO)2 + 2 NaHCO3 → Mg (HCO3)2 + 2CH3COONa
Step 2: Mg (HCO3)2 solution which is known as magnesium bicarbonate is obtained in which water is produced by the reaction of magnesium hydroxide (or milk of magnesia) with pressurized carbon dioxide (seltzer water). The reaction is,
Mg (OH)2 + 2CO2 → Mg (HCO3)2
The solution which is obtained when dried decomposes, turns magnesium bicarbonate to magnesium carbonate with release of water and carbon dioxide:
Mg +2HCO3 → MgCO3 +CO2 + H2O
Thermal Decomposition of Magnesium Bicarbonate
If Magnesium hydroxide is treated in a reaction with pressurized carbon dioxide, a solution of magnesium bicarbonate is obtained- Mg(OH)2 + 2CO2 → Mg(HCO3)2
Then when the resulting solution is heated, it causes the decomposition of the magnesium bicarbonate and giving out carbon dioxide, water and magnesium carbonate:
Mg2+ + 2 HCO3- → MgCO3 + CO2 + H2O
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Things to Remember
- Magnesium Bicarbonate plays an important role in human body
- Magnesium Bicarbonate is required in high concentration by our body to excrete Calcium from soft tissues
- Magnesium Bicarbonate has existence only in Solution form with a positive charge of +2.
- IUPAC name of Magnesium Bicarbonate is Magnesium Hydrogen Carbonate
Sample Questions
Ques Why is Magnesium Bicarbonate considered good for humans? (2 Marks)
Ans. Magnesium Bicarbonate is considered good for humans as:
- It helps in resisting changes in blood pH and Keeping it in optimal range
- It acts as an ingredient to help in regulating blood pressure, synthesis of protein, controlling blood glucose in human body
Ques. Should one consume magnesium every day? (2 Marks)
Ans. Yes, Magnesium can be consumed every day. One should consume less than 350g on a daily basis which is considered safe for adults. Excessive magnesium can cause side effects like - vomiting, diarrhea, etc
Ques. If Magnesium Bicarbonate is boiled in an aqueous solution, what products will be formed? (2 Marks)
Ans. If Magnesium Bicarbonate is boiled in an aqueous solution, the reaction will be
Mg (HCO3)2 → MgCO3 + H2O + CO2 +Mg (OH)2
Hence, the products that we get are MgCO3, water and carbon dioxide.
Ques. What is the rate of solubility of magnesium bicarbonate? (2 Marks)
Ans. The basic magnesium carbonate is soluble in distilled water which is saturated with carbon dioxide at a temperature of 25 degree Celsius. The solubility of Magnesium bicarbonate is 0.77g/100mL.
Ques. How do Magnesium bicarbonates help maintain pH of the body? (2 Marks)
Ans. Magnesium is used to remove the acids produced by the body. Our body must have a pH of 7.4 which is slightly alkaline for the well-being and performance of our body. Usage of Magnesium bicarbonate for a long time is considered safe as it buffers with the acidic compounds present in the body and balances the pH of the body which is very much essential.
Also Read: Acids, Bases and Salts - Important Notes
Ques. What are the causes of permanent and temporary hardness of Water? (3 Marks)
Ans. Permanent Hardness: In water, when Magnesium and calcium chlorides or sulphides are dissolved in water, it causes permanent hardness. This permanent hardness cannot be removed by boiling water. This hardness has to be treated with washing soda for the removal of permanent hardness of water.
Temporary Hardness: Dissolving of unstable chemicals such as calcium hydrogen carbonate & Magnesium hydrogen carbonate causes temporary hardness in water, which can easily be removed by heating the hard water.
Ques. Explain the reaction of Magnesium Bicarbonate with hydrochloric acid. (5 Marks)
Ans. We can represent the reaction of Magnesium Bicarbonate with hydrochloric acid in various steps:
Step 1: the following reaction will take place in an aqueous solution
Mg (HCO3)2 (aq.) → Mg2+ (aq.) + 2HCO3- (aq.) [Dissociation takes place in Magnesium bicarbonate]
HCl (aq.) → H+ (aq.) + Cl- (aq.) [Dissociation takes place in hydrochloric acid]
Step 2: Now mixing the two above solutions, we will obtain
H2CO3 → CO2 (g) + H2O (l)
If we see the overall reaction, we get,
Mg (HCO3)2 (aq.) + 2 HCl (aq.) → MgCl2 (aq.) + 2H2O (l) + 2CO2 (g)
So, it is clear that the reaction of magnesium bicarbonate with hydrochloric acid will result in the removal of water with carbon dioxide and the formation of Magnesium chloride.
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