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Magnesium metasilicate

Magnesium metasilicate

Last updated: March 19, 2023

Magnesium metasilicate is an inorganic compound with formula MgSiO₃.

Table of contents

Names

List of substance names

Nomenclature

Name

Typical name: Magnesium metasilicate

Compositional nomenclature: Magnesium metasilicate; Magnesium silicate

Additive nomenclature: Magnesium trioxidosilicate(2−); Magnesium catena-poly[(dioxidosilicate-μ-oxido)(2−)]

IUPAC acceptable common names: Magnesium metasilicate

Formulae and structures

List of formulae

Formula name

Formula

Typical formula: MgSiO₃

Compositional formula: MgSiO₃; Mg_n(SiO₃)_n

Structural formula

Structural formula with no conjugation

Lewis structure

Colored Lewis structure

Properties

List of substance properties

Item

Value

Name: Magnesium metasilicate

Formula: MgSiO₃

Appearance: Colorless solid

Odor: Odorless

Molar mass: 100.387 g/mol

Density: 3.192 g/cm³^[1]
Solid, 25°C

Melting point: 1557 °C^[1]
Decompose → MgO, SiO₂

Boiling point: –

Constituents

Constituent ions

Ion	Name	Charge number	Number
Mg²⁺	Magnesium ion	2	1
SiO₃²⁻	Metasilicate ion	-2	1

Constituent atoms

Atom	Name	Oxidation state	Number
Mg	Magnesium	+2	1
Si	Silicon	+4	1
O	Oxygen	−2	3

Ratio of atoms

Atom	Atomic weight	Number	Atomic ratio	Weight ratio
Mg	24.305	1	20.00%	24.21%
Si	28.085	1	20.00%	27.98%
O	15.999	3	60.00%	47.81%

Thermodynamic properties

Phase transition properties

Item

Value

Enthalpy of fusion: 71 kJ · mol⁻¹^[1]
at 1557°C

Enthalpy of vaporization: –

Enthalpy of vaporization at 25°C: –

Enthalpy of other transition: 0.67 kJ · mol⁻¹^[1]
at 630°C; 1.63 kJ · mol⁻¹^[1]
at 985°C

Standard thermodynamic properties

State	Standard enthalpy of formation Δ_fH° kJ · mol⁻¹	Standard Gibbs energy of formation Δ_fG° kJ · mol⁻¹	Standard molar entropy S° J · K⁻¹ · mol⁻¹	Standard molar heat capacity at constant pressure C_p° J · K⁻¹ · mol⁻¹
Crystalline solid	−1549.00^[2]	−1462.09^[2]	67.74^[2]	81.38^[2]

Solubility

Qualitative solubility

Reactive

Miscible

Very soluble

Soluble

Slightly soluble

Very slightly soluble: HF (aq)^[1]Hydrofluoric acid

Insoluble: H₂O^[1]Water

Preparations

Reaction of acid and base

The reaction of acid and base can yield magnesium metasilicate.

Reaction of metasilicic acid and magnesium hydroxide ◆ Δ_rG −10.4 kJ/mol K 6.64 × 10¹ pK −1.82: H₂SiO₃Metasilicic acid + Mg(OH)₂Magnesium hydroxide
⟶
MgSiO₃Magnesium metasilicate + 2H₂OWater

Reaction of silicic acid and magnesium hydroxide ◆ Δ_rG −7.1 kJ/mol K 1.75 × 10¹ pK −1.24: H₄SiO₄Silicic acid + Mg(OH)₂Magnesium hydroxide
⟶
MgSiO₃Magnesium metasilicate + 3H₂OWater

Reaction of base and acidic oxide

The reaction of magnesium hydroxide and silicon dioxide yields magnesium metasilicate and water.

Reaction of magnesium hydroxide and silicon dioxide ◆ Δ_rG −9.07 kJ/mol K 3.88 × 10¹ pK −1.59: Mg(OH)₂Magnesium hydroxide + SiO₂Silicon dioxide
⟶
MgSiO₃Magnesium metasilicate + H₂OWater

Reaction of basic oxide and acid

The reaction of basic oxide and acid can yield magnesium metasilicate.

Reaction of magnesium oxide and metasilicic acid ◆ Δ_rG −40.9 kJ/mol K 1.46 × 10⁷ pK −7.17: MgOMagnesium oxide + H₂SiO₃Metasilicic acid
⟶
MgSiO₃Magnesium metasilicate + H₂OWater

Reaction of magnesium oxide and silicic acid ◆ Δ_rG −37.5 kJ/mol K 3.71 × 10⁶ pK −6.57: MgOMagnesium oxide + H₄SiO₄Silicic acid
⟶
MgSiO₃Magnesium metasilicate + 2H₂OWater

Reaction of basic oxide and acidic oxide

The reaction of magnesium oxide and silicon dioxide yields magnesium metasilicate.

Reaction of magnesium oxide and silicon dioxide ◆ Δ_rG −39.50 kJ/mol K 8.32 × 10⁶ pK −6.92: MgOMagnesium oxide + SiO₂Silicon dioxide
⟶
MgSiO₃Magnesium metasilicate

Reaction of salt of weak base and strong base

The reaction of salt of weak base and strong base can yield magnesium metasilicate.

Reaction of manganese(II) metasilicate and magnesium hydroxide ◆ Δ_rG −3.1 kJ/mol K 3.49 × 10⁰ pK −0.54: MnSiO₃Manganese(II) metasilicate + Mg(OH)₂Magnesium hydroxide
⟶
MgSiO₃Magnesium metasilicate + Mn(OH)₂Manganese(II) hydroxide

Reaction of iron(II) metasilicate and magnesium hydroxide: FeSiO₃Iron(II) metasilicate + Mg(OH)₂Magnesium hydroxide
⟶
MgSiO₃Magnesium metasilicate + Fe(OH)₂Iron(II) hydroxide

Precipitation reaction

When magnesium ion and metasilicate ion react in aqueous solution, a precipitate of magnesium metasilicate is formed.

Reaction of magnesium chloride and sodium metasilicate ◆ Δ_rG −175.78 kJ/mol K 6.24 × 10³⁰ pK −30.80: MgCl₂Magnesium chloride + Na₂SiO₃Sodium metasilicate
💧
⟶
MgSiO₃↓Magnesium metasilicate + 2NaClSodium chloride

Reaction of magnesium bromide and sodium metasilicate ◆ Δ_rG −193.5 kJ/mol K 7.94 × 10³³ pK −33.90: MgBr₂Magnesium bromide + Na₂SiO₃Sodium metasilicate
💧
⟶
MgSiO₃↓Magnesium metasilicate + 2NaBrSodium bromide

Reaction of magnesium iodide and sodium metasilicate ◆ Δ_rG −213.2 kJ/mol K 2.24 × 10³⁷ pK −37.35: MgI₂Magnesium iodide + Na₂SiO₃Sodium metasilicate
💧
⟶
MgSiO₃↓Magnesium metasilicate + 2NaISodium iodide

Reaction of magnesium chloride and potassium metasilicate: MgCl₂Magnesium chloride + K₂SiO₃Potassium metasilicate
💧
⟶
MgSiO₃↓Magnesium metasilicate + 2KClPotassium chloride

Reaction of magnesium bromide and potassium metasilicate: MgBr₂Magnesium bromide + K₂SiO₃Potassium metasilicate
💧
⟶
MgSiO₃↓Magnesium metasilicate + 2KBrPotassium bromide

Reaction of active metal and acid

The reaction of magnesium and metasilicic acid yields magnesium metasilicate and hydrogen.

Reaction of magnesium and metasilicic acid ◆ Δ_rG −369.7 kJ/mol K 5.87 × 10⁶⁴ pK −64.77: MgMagnesium + H₂SiO₃Metasilicic acid
⟶
MgSiO₃Magnesium metasilicate + H₂↑Hydrogen

Reaction of active metal, acidic oxide, and water

The reaction of magnesium, silicon dioxide, and water yields magnesium metasilicate and hydrogen.

Reaction of magnesium, silicon dioxide, and water ◆ Δ_rG −368.32 kJ/mol K 3.36 × 10⁶⁴ pK −64.53: MgMagnesium + SiO₂Silicon dioxide + H₂OWater
⟶
MgSiO₃Magnesium metasilicate + H₂↑Hydrogen

Chemical reactions

Electrolytic dissociation

Electrolytic dissociation of magnesium metasilicate yields magnesium ion and metasilicate ion.

Electrolytic dissociation of magnesium metasilicate: MgSiO₃Magnesium metasilicate
⟶
Mg²⁺Magnesium ion + SiO₃²⁻Metasilicate ion

Reaction with strong acid

The reaction of magnesium metasilicate and strong acid yields salt of strong acid and metasilicic acid.

Reaction of magnesium metasilicate and hydrogen chloride ◆ Δ_rG −31.5 kJ/mol K 3.30 × 10⁵ pK −5.52: MgSiO₃Magnesium metasilicate + 2HClHydrogen chloride
⟶
MgCl₂Magnesium chloride + H₂SiO₃Metasilicic acid

Reaction of magnesium metasilicate and hydrogen bromide ◆ Δ_rG −27.2 kJ/mol K 5.82 × 10⁴ pK −4.77: MgSiO₃Magnesium metasilicate + 2HBrHydrogen bromide
⟶
MgBr₂Magnesium bromide + H₂SiO₃Metasilicic acid

Reaction of magnesium metasilicate and hydrogen iodide ◆ Δ_rG 8.1 kJ/mol K 0.38 × 10⁻¹ pK 1.42: MgSiO₃Magnesium metasilicate + 2HIHydrogen iodide
⟶
MgI₂Magnesium iodide + H₂SiO₃Metasilicic acid

Reaction of magnesium metasilicate and hydrogen chloride ◆ Δ_rG −32.87 kJ/mol K 5.74 × 10⁵ pK −5.76: MgSiO₃Magnesium metasilicate + 2HClHydrogen chloride
⟶
MgCl₂Magnesium chloride + SiO₂Silicon dioxide + H₂OWater

Reaction of magnesium metasilicate and sulfuric acid ◆ Δ_rG −110.9 kJ/mol K 2.68 × 10¹⁹ pK −19.43: MgSiO₃Magnesium metasilicate + H₂SO₄Sulfuric acid
⟶
MgSO₄Magnesium sulfate + H₂SiO₃Metasilicic acid

Reaction with reducing species

The reaction of reducing species and magnesium metasilicate yields a variety of products.

Reaction of sodium and magnesium metasilicate ◆ Δ_rG −237.18 kJ/mol K 3.57 × 10⁴¹ pK −41.55: 4NaSodium + 3MgSiO₃Magnesium metasilicate
⟶
2Na₂SiO₃Sodium metasilicate + SiSilicon + 3MgOMagnesium oxide

Reaction of sodium and magnesium metasilicate ◆ Δ_rG 145.22 kJ/mol K 0.36 × 10⁻²⁵ pK 25.44: 4NaSodium + MgSiO₃Magnesium metasilicate
🔥
⟶
2Na₂OSodium oxide + SiSilicon + MgOMagnesium oxide

Decomposition

Decomposition of magnesium metasilicate yields magnesium oxide and silicon dioxide.

Decomposition of magnesium metasilicate ◆ Δ_rG 39.50 kJ/mol K 0.12 × 10⁻⁶ pK 6.92: MgSiO₃Magnesium metasilicate
🔥
⟶
MgOMagnesium oxide + SiO₂Silicon dioxide

Decomposition of magnesium metasilicate ◆ Δ_rG 896.14 kJ/mol K 0.10 × 10⁻¹⁵⁶ pK 157.00: MgSiO₃Magnesium metasilicate
🔥
⟶
MgOMagnesium oxide + SiSilicon + O₂↑Oxygen

Decomposition of magnesium metasilicate ◆ Δ_rG 3014.8 kJ/mol K 0.68 × 10⁻⁵²⁸ pK 528.17: 3MgSiO₃Magnesium metasilicate
🔥
⟶
3MgOMagnesium oxide + 3SiSilicon + 2O₃↑Ozone

References

List of references

1
James G. Speight (2017)
Lange's Handbook of Chemistry, 17th edition
https://www.accessengineeringlibrary.com/content/book/9781259586095
McGraw Hill Education
- Amazon
Citation list
- ^ Density, 3.192 g/cm³ - p.51
- ^ Melting point, 1557 °C - p.51
- ^ Enthalpy of fusion, 71 kJ · mol⁻¹ - p.304
- ^ Enthalpy of other transition, 0.67 kJ · mol⁻¹ - p.304
- ^ Enthalpy of other transition, 1.63 kJ · mol⁻¹ - p.304
- ^ Qualitative solubility, Insoluble in water - p.51
- ^ Qualitative solubility, Very slightly soluble in hydrofluoric acid - p.51
2
Janiel J. Reed (1989)
The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI Units
https://doi.org/10.18434/M32124
National Institute of Standards and Technology (NIST)
Citation list

Δ_rG	−10.4 kJ/mol
K	6.64 × 10¹
pK	−1.82

Δ_rG	−7.1 kJ/mol
K	1.75 × 10¹
pK	−1.24

Δ_rG	−9.07 kJ/mol
K	3.88 × 10¹
pK	−1.59

Δ_rG	−40.9 kJ/mol
K	1.46 × 10⁷
pK	−7.17