Content Writer
Manganese (II) chloride with the chemical formula MnCl2 is the dichloride salt of manganese. It is generally found in tetrahydrate form (MnCl2.4H2O).
- Two other forms of manganese (II) chloride are anhydrous and dihydrate (MnCl2.2H2O).
- An anhydrous form of manganese (II) chloride is found as a mineral called scacchite.
- It is a silvery-white metal that is prepared by a chemical reaction between manganese oxide and hydrochloric acid.
- The aqueous solution of manganese (II) chloride is used in the process to determine the size of sheets of phospholipid vesicles.
- Moreover, dry cell batteries are made with the use of dichloride salt of manganese.
- You will be surprised to know it is used in many food items like nuts, grains, tea, and green leafy vegetables.
Key Terms: Manganese (II) Chloride Formula, Manganese (II) Chloride, Manganese, Mineral, Monopotassium Phosphate Formula, Manganese Oxide, Hydrochloric Acid
Manganese (II) Chloride Formula Structure
[Click Here for Sample Questions]
In manganese (II) chloride, the elements manganese and chlorine are bonded together with an ionic bond. The structure of this inorganic compound varies depending on its hydration state.
- The chemical formula for Manganese (II) Chloride is divided into three categories, which are as follows:
Anhydrous form: MnCl2
The anhydrous form of manganese chloride is a white, crystalline solid with no water molecules. It is composed of manganese ions, which have a charge of +2, bonded with chloride ions, which have a charge of -1.
Manganese (II) Chloride Anhydrous form
Dihydrate form: MnCl2.2H2O
The dihydrate form of Manganese (II) Chloride is a pale pink crystalline solid with two water molecules. In this structure, manganese ions are surrounded by chloride ions and water molecules.
Tetrahydrate form: MnCl2.4H2O
In the tetrahydrate form four water molecules surrounds the manganese ions along with the chloride ions. This forms a pale pink or light red crystalline solid.
Manganese (II) Chloride Tetrahydrate form
| Chemistry Related Concepts | ||
|---|---|---|
| Ammonia | Organic Compounds | S- Block Elements |
| Oxidizing Agent | Silicon dioxide | The Alkali Metals |
Preparation of Manganese (II) Chloride
[Click Here for Sample Questions]
Various ways for preparation of Manganese (II) Chloride are as follows:
- When manganese (IV) oxide (MnO2) and concentrated hydrochloric acid (HCl) are heated together then gives the required product, manganese (II) chloride along with chlorine and water. Earlier, this method was used for the preparation of chlorine.
MnO2 + 4 HCl → MnCl2 + 2 H2O + Cl2
- Tetrahydrate form can be prepared by reacting the manganese metal (Mn) with the hydrochloric acid (HCl) in the presence of water (H2O). The resulting product involves hydrogen molecules (H2) also.
Mn + 2 HCl + 4 H2O → MnCl2(H2O)4 + H2
- Carbon dioxide and tetrahydrate form of manganese (II) chloride are the products of the chemical reaction between manganese (II) carbonate and hydrochloric acid in presence of water.
MnCO3 + 2 HCl + 3 H2O → MnCl2(H2O)4 + CO2
Properties of Manganese (II) Chloride
[Click Here for Sample Questions]
The physical and chemical properties of Manganese (II) Chloride are as follows:
Physical Properties of Manganese (II) Chloride
The physical properties are as follows:
- Manganese (II) chloride is a paramagnetic salt that is pink, like other species of Manganese (II).
- The melting and boiling point of the compound is 654 °C and 1225 °C respectively.
- Moreover, the density is 2.977 g/cm3 for the anhydrous form but 2.27 g/cm3 and 2.01 g/cm3 for dihydrate and tetrahydrate forms.
- An anhydrous form of Manganese (II) chloride with the compound formula MnCl2 has a molar mass of 125.844 amu.
- The dihydrate and tetrahydrate form of the compound has a molar mass of 161.874 amu and 197.91 amu, respectively.
- The compound is soluble in water and ethanol but insoluble in ether.
The physical properties are tabulated below:
| Compound | Data |
|---|---|
| Chemical formula | MnCl2 |
| Molecular weight | 125.844 g/mol (anhydrous), 161.874 g/mol (dihydrate) and 197.91 g/mol (tetrahydrate) |
| Density | 2.977 g/cm3 (anhydrous), 2.27 g/cm3 (dihydrate) and 2.01 g/cm3 (tetrahydrate) |
| Melting point | 654 °C (anhydrous), 135 °C (dihydrate) and 58 °C (tetrahydrate) |
| Boiling point | 1,225 °C (2,237 °F; 1,498 K) |
Chemical Properties of Manganese (II) Chloride
The chemical properties are as follows:
Acidic Characteristics
Lewis acid is a chemical compound that can accept a pair of nonbonding electrons or is classified as an electron-pair acceptor. So, manganese (II) chloride is a weak Lewis acid that gives ions such as [MnCl3]−, [MnCl4]2−, and [MnCl6]4− when reacted with chlorine ions. The pH value is around 4 when the hydrate is dissolved in water.
Treatment with Organic ligands
Mn(III) complexes, such as include [Mn(EDTA)]− and [Mn(CN)6]3− are the by-product of the chemical reaction of MnCl2 with organic ligands as it undergoes oxidation by air. For example,
MnCl2 + 2 Ph3P → [MnCl2(Ph3P)2]
Formation of Manganese Compounds
Anhydrous manganese(II) chloride is used in the formation of various manganese compounds such as manganocene. When MnCl2 reacts with a solution of sodium cyclopentadienide to give the compound manganocene along with sodium chloride. This reaction takes place in presence of tetrahydrofuran.
MnCl2 + 2 NaC5H5 → Mn(C5H5)2 + 2 NaCl
Uses of Manganese(II) Chloride
[Click Here for Sample Questions]
Various applications of Manganese(II) Chloride are as follows:
- MnCl2 is used in daily life for the treatment of magnesium deficiency in humans.
- It is used in the production of magnesium metal by the process of electrolysis.
- Manganese (II) chloride is used as a contrasting agent in MRI scanning.
- The compound is used in the assembly of Leclanche cell batteries.
- The aqueous solutions of manganese (II) chloride are used in the preparation of P-NMR.
Read More:
| Chapter Related Concepts | ||
|---|---|---|
| Potassium Dichromate | Elimination Reaction | Sulfates |
| Stereochemistry | Sodium peroxide. | Carbonates |
Things to Remember
- Manganese (II) chloride is found in three different forms, generally in tetrahydrate.
- It is found in rare mineral scacchite.
- MnCl2 is completely soluble in water.
- The salt manganese (II) chloride is paramagnetic in nature.
- Solubility of the compound increases with increase in temperature.
- The pH of aqueous solution of MnCl2 is 4.
- It is used for the production of manganese carbonate and manganese (II) oxide.
Sample Questions
Ques: Describe the solubility of manganese (II) chloride? (2 marks)
Ans: Manganese (II) chloride is completely soluble in water as well as ethanol. At 0 °C, 3.4 g of compound can dissolve in 100 ml of water but it increases with the temperature as 73.9 g of MnCl2 is soluble in same amount of water when the temperature rises to 20 °C. Moreover, it is slightly soluble in pyridine whereas insoluble in ether.
Ques: How can we prepare manganocene from manganese (II) chloride? (3 marks)
Ans: Manganocene with the chemical formula Mn(C5H5)2 is prepared by the help of manganese (II) chloride which acts as a reactant and reacts with a solution of sodium cyclopentadienide (NaC5H5) in the presence of the tetrahydrofuran (THF).
MnCl2 + 2 NaC5H5 → Mn(C5H5)2 + 2 NaCl
Anhydrous manganese (II) chloride is used as a primary compound in the formation of manganese compounds.
Ques: Explain the paramagnetic nature of the salt manganese (II) chloride? (2 marks)
Ans: Paramagnetic salts are the salts which consists of transition metal ions that have at least one unpaired electron in their electron configuration. It is found in pink colour but it fades which reflects the transition metal complexes with high spin d5 configuration. This property of MnCl2 is used in MRI scanning and highlight neural pathway.
Ques: What is manganese (II) chloride used for? (2 marks)
Ans: Due to the behaviour of MnCl2 as paramagnetic salt, it is used in MRI scanning. When it is dissolved in water, the solution is used in P-NMR for determining the size of phospholipid vesicles. Moreover, the salt is key integrant in dry cell batteries. Also, chloride compounds can conduct electricity when fused in water.
Ques: Is manganese (II) chloride harmful for health? (2 marks)
Ans: An inorganic compound manganese (II) chloride may be harmful for health as it causes respiratory tract irritation inhaled. It also causes skin and eyes irritation when comes in contact with the skin or eyes. Moreover, it affects the ingestion if swallowed. Also, if an individual remains in the environment of manganese dust or fumes then it leads to Manganism or manganese poisoning.
Ques: What is manganism? (2 marks)
Ans: Manganism, also known as manganese poisoning is a disease identified by James Couper in 1837. It is because of chronic exposure to manganese. The symptoms of manganism are mood changes, reduced response speed, irritability and compulsive behaviour. It is highly spoken issue in work regions due to the safety of the welders and their interaction with the manganese compound salts.
Ques: What type of bond is formed in Manganese (II) chloride? (2 marks)
Ans: Ionic bonds is the type of bond because of the attraction between two oppositely charged ions in the compound. Manganese (II) chloride is an inorganic compound in which Manganese (Mn) is bonded with two chlorine (Cl) atoms with ionic bond. In MnCl2, two ions i.e., Mg2+ and 2 Cl- are linked together and thus forms the ionic bond.
Ques: Is manganese (II) chloride a solid, liquid or gas? (2 marks)
Ans: An anhydrous form of manganese (II) chloride is polymeric solid in nature. It is mostly found in its tetrahydrate form which is pink in colour. It is in layered cadmium chloride like structure. Also, manganese chloride along with other salts of the manganese solution precipitates when added to the sodium hydroxide.
Ques: What type of acids is manganese (II) chloride? (2 marks)
Ans: The nature of the compound is classified by the value of pH. When manganese (II) chloride dissolve in water, it gives mildly acidic solution of approximately pH value 4. These solutions consist of the metal aquo complex [Mn(H2O)6]2+. It is considered as Lewis’s acid because it gives ions [MnCl3]−, [MnCl4]2−, and [MnCl6]4− when reacted with chlorine.
Ques: How tetrahydrate form is converted to anhydrous form of manganese (II) chloride? (2 marks)
Ans: When the tetrahydrate form of manganese (II) chloride is heated at the temperature of 198°C or less then it is separate the manganese chloride and water. The heating should be placed in vacuum condition. Hence, anhydrous form of MnCl2 is obtained.
MnCl2.4H2O → MnCl2 + 4H2O
Ques: What is the molecular mass of dihydrate form of manganese (II) chloride? (3 marks)
Ans: Here, atomic mass of Manganese (Mn) = 55 amu (approx.)
atomic mass of Chlorine (Cl) = 35 amu (approx.)
atomic mass of Hydrogen (H) = 1 amu
atomic mass of Oxygen (O) = 16 amu
So, molecular mass of MnCl2.2H2O = atomic mass of Manganese (Mn) + 2 × atomic mass of Chlorine (Cl) + 4 × atomic mass of hydrogen(H) + 2 × atomic mass of Oxygen(O)
Molecular mass of MnCl2.2H2O = 55 + 2×35 + 4×1 + 2× 16 amu
Molecular mass of MnCl2.2H2O = 55 + 70 + 4 + 32 amu
Molecular mass of MnCl2.2H2O = 161 amu
The exact mass of MnCl2.2H2O is 161.874 amu.
Read Also:
Comments