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Calcium arsenate

Calcium arsenate

Last updated: March 19, 2023

Calcium arsenate is an inorganic compound with formula Ca₃(AsO₄)₂.

Table of contents

Names

List of substance names

Nomenclature

Name

Typical name: Calcium arsenate

Compositional nomenclature: Calcium arsenate; Tricalcium bis(arsenate)

Additive nomenclature: Calcium tetraoxidoarsenate

Other names: Calcium arsonate

Formulae and structures

List of formulae

Formula name

Formula

Typical formula: Ca₃(AsO₄)₂

Compositional formula: Ca₃(AsO₄)₂

Structural formula

Other structural formulas

Lewis structure

Colored Lewis structure

Properties

List of substance properties

Item

Value

Name: Calcium arsenate

Formula: Ca₃(AsO₄)₂

Appearance: Colorless solid

Odor: Odorless

Molar mass: 398.070 g/mol

Density: 3.620 g/cm³^[1]
Solid

Melting point: –

Boiling point: –

Constituents

Constituent ions

Ion	Name	Charge number	Number
Ca²⁺	Calcium ion	2	3
AsO₄³⁻	Arsenate ion	-3	2

Constituent atoms

Atom	Name	Oxidation state	Number
Ca	Calcium	+2	3
As	Arsenic	+5	2
O	Oxygen	−2	8

Ratio of atoms

Atom	Atomic weight	Number	Atomic ratio	Weight ratio
Ca	40.078	3	23.08%	30.20%
As	74.922	2	15.38%	37.64%
O	15.999	8	61.54%	32.15%

Thermodynamic properties

Phase transition properties

Item

Value

Enthalpy of fusion: –

Enthalpy of vaporization: –

Enthalpy of vaporization at 25°C: –

Enthalpy of other transition: –

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	−3298.7^[2]	−3063.0^[2]	226.^[2]	–
Crystalline solid hydrated precipitate	−3343.^[2]	–	–	–

Solubility

Qualitative solubility

Reactive

Miscible

Very soluble

Soluble

Slightly soluble

Very slightly soluble: H₂OWater

Insoluble

Solubility in water (g/100 mL)^[1]

25°C
0.013

Solubility curve (g/100 mL)

Hazards

GHS label^[3]

Item

Value

Hazard pictograms: GHS06: Skull and crossbones; GHS07: Exclamation mark; GHS08: Health hazard

Signal word: Danger

Hazard statements: H301: Toxic if swallowed; H319: Causes serious eye irritation; H350: May cause cancer; H361: Suspected of damaging fertility or the unborn child; H370: Causes damage to organs; H370: Causes damage to respiratory system; H370: Causes damage to nervous system; H370: Causes damage to blood system; H370: Causes damage to kidney; H370: Causes damage to circulatory system; H370: Causes damage to digestive system; H370: Causes damage to liver; H370: Causes damage to skin; H372: Causes damage to organs through prolonged or repeated exposure; H372: Causes damage to respiratory system through prolonged or repeated exposure; H372: Causes damage to blood system through prolonged or repeated exposure; H372: Causes damage to liver through prolonged or repeated exposure; H372: Causes damage to kidney through prolonged or repeated exposure; H372: Causes damage to nervous system through prolonged or repeated exposure; H372: Causes damage to skin through prolonged or repeated exposure; H372: Causes damage to circulatory system through prolonged or repeated exposure; H372: Causes damage to gastrointestinal digestive system through prolonged or repeated exposure

Physical hazards^[3]

Classification	Category	Label	Hazard statement
Explosives	Not applicable
Flammable gases	Not applicable
Aerosols	Not applicable
Oxidizing gases	Not applicable
Gases under pressure	Not applicable
Flammable liquids	Not applicable
Flammable solids	Not classified
Self reactive substances and mixtures	Not applicable
Pyrophoric liquids	Not applicable
Pyrophoric solids	Not classified
Self heating substances and mixtures	Not classified
Substances and mixtures which in contact with water emit flammable gases	Not classified
Oxidizing liquids	Not applicable
Oxidizing solids	Classification not possible
Organic peroxides	Not applicable
Substances and mixtures corrosive to metals	Classification not possible
Desensitized explosives	No data

Health hazards^[3]

Classification	Category	Label	Hazard statement
Acute oral toxicity	Category 3	Danger	H301: Toxic if swallowed
Acute dermal toxicity	Not classified
Acute inhalation toxicity by gas	Not applicable
Acute inhalation toxicity by vapor	Classification not possible
Acute inhalation toxicity by dust or mist	Classification not possible
Skin corrosion irritation	Classification not possible
Serious eye damage eye irritation	Category 2	Warning	H319: Causes serious eye irritation
Respiratory sensitization	Classification not possible
Skin sensitization	Classification not possible
Germ cell mutagenicity	Classification not possible
Carcinogenicity	Category 1A	Danger	H350: May cause cancer
Reproductive toxicity	Category 2	Warning	H361: Suspected of damaging fertility or the unborn child
Specific target organ toxicity single exposure	Category 1 (Respiratory system, Nervous system, Blood system, Kidney, Circulatory system, Digestive system, Liver, Skin)	Danger	H370: Causes damage to organs H370: Causes damage to respiratory system H370: Causes damage to nervous system H370: Causes damage to blood system H370: Causes damage to kidney H370: Causes damage to circulatory system H370: Causes damage to digestive system H370: Causes damage to liver H370: Causes damage to skin
Specific target organ toxicity repeated exposure	Category 1 (Respiratory system, Blood system, Liver, Kidney, Nervous system, Skin, Circulatory system, Digestive system)	Danger	H372: Causes damage to organs through prolonged or repeated exposure H372: Causes damage to respiratory system through prolonged or repeated exposure H372: Causes damage to blood system through prolonged or repeated exposure H372: Causes damage to liver through prolonged or repeated exposure H372: Causes damage to kidney through prolonged or repeated exposure H372: Causes damage to nervous system through prolonged or repeated exposure H372: Causes damage to skin through prolonged or repeated exposure H372: Causes damage to circulatory system through prolonged or repeated exposure H372: Causes damage to gastrointestinal digestive system through prolonged or repeated exposure
Aspiration hazard	Classification not possible

Environmental hazards^[3]

Classification	Category	Label	Hazard statement
Hazardous to the aquatic environment short term	Classification not possible
Hazardous to the aquatic environment long term	Classification not possible
Hazardous to the ozone layer	No data

Preparations

Precipitation reaction

When calcium ion and arsenate ion react in aqueous solution, a precipitate of calcium arsenate is formed.

Reaction of calcium chloride and sodium arsenate ◆ Δ_rG −105.5 kJ/mol K 3.04 × 10¹⁸ pK −18.48: 3CaCl₂Calcium chloride + 2Na₃AsO₄Sodium arsenate
💧
⟶
Ca₃(AsO₄)₂↓Calcium arsenate + 6NaClSodium chloride

Reaction of calcium bromide and sodium arsenate ◆ Δ_rG −105.4 kJ/mol K 2.92 × 10¹⁸ pK −18.47: 3CaBr₂Calcium bromide + 2Na₃AsO₄Sodium arsenate
💧
⟶
Ca₃(AsO₄)₂↓Calcium arsenate + 6NaBrSodium bromide

Reaction of calcium iodide and sodium arsenate ◆ Δ_rG −105.4 kJ/mol K 2.92 × 10¹⁸ pK −18.47: 3CaI₂Calcium iodide + 2Na₃AsO₄Sodium arsenate
💧
⟶
Ca₃(AsO₄)₂↓Calcium arsenate + 6NaISodium iodide

Reaction of calcium chloride and potassium arsenate ◆ Δ_rG −105.5 kJ/mol K 3.04 × 10¹⁸ pK −18.48: 3CaCl₂Calcium chloride + 2K₃AsO₄Potassium arsenate
💧
⟶
Ca₃(AsO₄)₂↓Calcium arsenate + 6KClPotassium chloride

Reaction of calcium bromide and potassium arsenate ◆ Δ_rG −105.5 kJ/mol K 3.04 × 10¹⁸ pK −18.48: 3CaBr₂Calcium bromide + 2K₃AsO₄Potassium arsenate
💧
⟶
Ca₃(AsO₄)₂↓Calcium arsenate + 6KBrPotassium bromide

Reaction of active metal and acid

The reaction of calcium and arsenic acid yields calcium arsenate and hydrogen.

Reaction of calcium and arsenic acid ◆ Δ_rG −1531.0 kJ/mol K 1.66 × 10²⁶⁸ pK −268.22: 3CaCalcium + 2H₃AsO₄Arsenic acid
⟶
Ca₃(AsO₄)₂Calcium arsenate + 3H₂↑Hydrogen

Reaction of nonmetal and hydroxide base

The reaction of arsenic and calcium hydroxide yields calcium arsenate, arsine, and calcium oxide.

Reaction of arsenic and calcium hydroxide ◆ Δ_rG 1353.5 kJ/mol K 0.75 × 10⁻²³⁷ pK 237.12: 16AsArsenic + 15Ca(OH)₂Calcium hydroxide
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⟶
3Ca₃(AsO₄)₂Calcium arsenate + 10AsH₃↑Arsine + 6CaOCalcium oxide

Reaction of nonmetal, base, and water

The reaction of arsenic, calcium hydroxide, and water yields calcium arsenate and arsine.

Reaction of arsenic, calcium hydroxide, and water ◆ Δ_rG 1009.5 kJ/mol K 0.14 × 10⁻¹⁷⁶ pK 176.86: 16AsArsenic + 9Ca(OH)₂Calcium hydroxide + 6H₂OWater
🔥
⟶
3Ca₃(AsO₄)₂Calcium arsenate + 10AsH₃↑Arsine

Chemical reactions

Electrolytic dissociation

Electrolytic dissociation of calcium arsenate yields calcium ion and arsenate ion.

Electrolytic dissociation of calcium arsenate ◆ Δ_rG 105.4 kJ/mol K 0.34 × 10⁻¹⁸ pK 18.47: Ca₃(AsO₄)₂Calcium arsenate
⟶
3Ca²⁺Calcium ion + 2AsO₄³⁻Arsenate ion

Reaction with strong acid

The reaction of calcium arsenate and strong acid yields salt of strong acid and arsenic acid.

Reaction of calcium arsenate and hydrogen chloride ◆ Δ_rG −129.7 kJ/mol K 5.28 × 10²² pK −22.72: Ca₃(AsO₄)₂Calcium arsenate + 6HClHydrogen chloride
⟶
3CaCl₂Calcium chloride + 2H₃AsO₄Arsenic acid

Reaction of calcium arsenate and hydrogen bromide ◆ Δ_rG −129.7 kJ/mol K 5.28 × 10²² pK −22.72: Ca₃(AsO₄)₂Calcium arsenate + 6HBrHydrogen bromide
⟶
3CaBr₂Calcium bromide + 2H₃AsO₄Arsenic acid

Reaction of calcium arsenate and hydrogen iodide ◆ Δ_rG −129.7 kJ/mol K 5.28 × 10²² pK −22.72: Ca₃(AsO₄)₂Calcium arsenate + 6HIHydrogen iodide
⟶
3CaI₂Calcium iodide + 2H₃AsO₄Arsenic acid

Reaction of calcium arsenate and perchloric acid ◆ Δ_rG −129.7 kJ/mol K 5.28 × 10²² pK −22.72: Ca₃(AsO₄)₂Calcium arsenate + 6HClO₄Perchloric acid
⟶
3Ca(ClO₄)₂Calcium perchlorate + 2H₃AsO₄Arsenic acid

Reaction of calcium arsenate and hydrogen chloride ◆ Δ_rG −103.2 kJ/mol K 1.20 × 10¹⁸ pK −18.08: Ca₃(AsO₄)₂Calcium arsenate + 6HClHydrogen chloride
⟶
3CaCl₂Calcium chloride + As₂O₅Diarsenic pentaoxide + 3H₂OWater

Reaction with reducing species

The reaction of reducing species and calcium arsenate yields a variety of products.

Reaction of hydrogen and calcium arsenate ◆ Δ_rG 65.3 kJ/mol K 0.36 × 10⁻¹¹ pK 11.44: 5H₂Hydrogen + Ca₃(AsO₄)₂Calcium arsenate
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⟶
2AsArsenic + 3CaOCalcium oxide + 5H₂OWater

Reaction of sodium and calcium arsenate ◆ Δ_rG −626.4 kJ/mol K 5.50 × 10¹⁰⁹ pK −109.74: 10NaSodium + Ca₃(AsO₄)₂Calcium arsenate
⟶
5Na₂OSodium oxide + 2AsArsenic + 3CaOCalcium oxide

Reaction of hydrogen and calcium arsenate ◆ Δ_rG −106.7 kJ/mol K 4.93 × 10¹⁸ pK −18.69: 5H₂Hydrogen + Ca₃(AsO₄)₂Calcium arsenate
⟶
2AsArsenic + 3Ca(OH)₂Calcium hydroxide + 2H₂OWater

Reaction of hydrogen sulfide and calcium arsenate ◆ Δ_rG 2.2 kJ/mol K 0.41 × 10⁰ pK 0.39: 8H₂SHydrogen sulfide + Ca₃(AsO₄)₂Calcium arsenate
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⟶
5SSulfur + 2AsArsenic + 3CaSCalcium sulfide + 8H₂OWater

Reaction of sodium and calcium arsenate ◆ Δ_rG −2167.0 kJ/mol K 4.39 × 10³⁷⁹ pK −379.64: 15NaSodium + 4Ca₃(AsO₄)₂Calcium arsenate
⟶
5Na₃AsO₄Sodium arsenate + 3AsArsenic + 12CaOCalcium oxide

Reaction with oxidizable species

The reaction of oxidizable species and calcium arsenate yields a variety of products.

Reaction of iron(II) oxide and calcium arsenate: 15FeOIron(II) oxide + Ca₃(AsO₄)₂Calcium arsenate
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⟶
5Fe₃O₄Iron(II,III) oxide + 2AsArsenic + 3CaOCalcium oxide

Reaction of iron(II) oxide and calcium arsenate: 10FeOIron(II) oxide + Ca₃(AsO₄)₂Calcium arsenate
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⟶
5Fe₂O₃Iron(III) oxide + 2AsArsenic + 3CaOCalcium oxide

Reaction of copper and calcium arsenate ◆ Δ_rG 602.4 kJ/mol K 0.29 × 10⁻¹⁰⁵ pK 105.54: 5CuCopper + Ca₃(AsO₄)₂Calcium arsenate
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⟶
5CuOCopper(II) oxide + 2AsArsenic + 3CaOCalcium oxide

Reaction of copper and calcium arsenate ◆ Δ_rG 520.9 kJ/mol K 0.55 × 10⁻⁹¹ pK 91.26: 10CuCopper + Ca₃(AsO₄)₂Calcium arsenate
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⟶
5Cu₂OCopper(I) oxide + 2AsArsenic + 3CaOCalcium oxide

Reaction of potassium iodide and calcium arsenate ◆ Δ_rG 3285.4 kJ/mol K 0.26 × 10⁻⁵⁷⁵ pK 575.58: 5KIPotassium iodide + 3Ca₃(AsO₄)₂Calcium arsenate
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⟶
5KIO₃Potassium iodate + 6AsArsenic + 9CaOCalcium oxide

Reaction with oxidizing species

The reaction of calcium arsenate and oxidizing species yields a variety of products.

Reaction of calcium arsenate and chlorine: 2Ca₃(AsO₄)₂Calcium arsenate + 10Cl₂Chlorine
⟶
6CaOCalcium oxide + 5O₂Oxygen + 4AsCl₅Arsenic pentachloride

Reaction of calcium arsenate and chlorine: Ca₃(AsO₄)₂Calcium arsenate + 8Cl₂Chlorine
⟶
3CaCl₂Calcium chloride + 4O₂Oxygen + 2AsCl₅Arsenic pentachloride

Decomposition

Decomposition of calcium arsenate yields calcium oxide and diarsenic pentaoxide.

Decomposition of calcium arsenate ◆ Δ_rG 468.6 kJ/mol K 0.80 × 10⁻⁸² pK 82.10: Ca₃(AsO₄)₂Calcium arsenate
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⟶
3CaOCalcium oxide + As₂O₅Diarsenic pentaoxide

Decomposition of calcium arsenate ◆ Δ_rG 674.7 kJ/mol K 0.63 × 10⁻¹¹⁸ pK 118.20: Ca₃(AsO₄)₂Calcium arsenate
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⟶
3CaOCalcium oxide + As₂O₃Diarsenic trioxide + O₂↑Oxygen

Decomposition of calcium arsenate ◆ Δ_rG 2501.8 kJ/mol K 0.51 × 10⁻⁴³⁸ pK 438.30: 2Ca₃(AsO₄)₂Calcium arsenate
🔥
⟶
6CaOCalcium oxide + 4AsArsenic + 5O₂↑Oxygen

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, 3.620 g/cm³ - p.36
- ^ Solubility in Water (g/100 mL), See the table - p.36
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
3
Chemical Management Center
GHS Classification Results
https://www.nite.go.jp/chem/english/ghs/all_fy_e.html
National Institute of Technology and Evaluation
Citation list

Δ_rG	−258.3 kJ/mol
K	1.79 × 10⁴⁵
pK	−45.25

Δ_rG	−296.6 kJ/mol
K	9.16 × 10⁵¹
pK	−51.96

Δ_rG	−430.3 kJ/mol
K	2.43 × 10⁷⁵
pK	−75.39

Δ_rG	−468.6 kJ/mol
K	1.24 × 10⁸²
pK	−82.10

Calcium arsenate

Names

List of substance names

Formulae and structures

List of formulae

Properties

List of substance properties

Constituents

Constituent ions

Constituent atoms

Ratio of atoms

Thermodynamic properties

Phase transition properties

Standard thermodynamic properties

Solubility

Qualitative solubility

Solubility in water (g/100 mL)[1]

Solubility curve (g/100 mL)

Hazards

GHS label[3]

Physical hazards[3]

Health hazards[3]

Environmental hazards[3]

Preparations

Reaction of acid and base

Reaction of base and acidic oxide

Reaction of basic oxide and acid

Reaction of basic oxide and acidic oxide

Reaction of salt of weak base and strong base

Precipitation reaction

Reaction of active metal and acid

Reaction of nonmetal and hydroxide base

Reaction of nonmetal, base, and water

Chemical reactions

Electrolytic dissociation

Reaction with strong acid

Reaction with reducing species

Reaction with oxidizable species

Reaction with oxidizing species

Decomposition

References

List of references

Related substances

Arsenate of alkaline earth metal

Acid and acidic oxide

Base and basic oxide

Related categories

Classification by constituent

Type of substance

State of substance

Property of substance

Solubility of substance

Color of substance

Odor of substance

Solubility in water (g/100 mL)^[1]

GHS label^[3]

Physical hazards^[3]

Health hazards^[3]

Environmental hazards^[3]