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Chemical reactions
3H2 + 2AgSCN → 2Ag + 2H2S + 2HCN

3H₂ + 2AgSCN → 2Ag + 2H₂S + 2HCN

Last updated: June 13, 2022

Reaction of hydrogen and silver(I) thiocyanate: 3H₂Hydrogen + 2AgSCNSilver(I) thiocyanate
⟶
2AgSilver + 2H₂SHydrogen sulfide + 2HCNHydrogen cyanide

The reaction of hydrogen and silver(I) thiocyanate yields silver, hydrogen sulfide, and hydrogen cyanide (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:

Reaction of reducing species and reducible species

Table of contents

Reaction data

Chemical equation

Reaction of hydrogen and silver(I) thiocyanate: 3H₂Hydrogen + 2AgSCNSilver(I) thiocyanate
⟶
2AgSilver + 2H₂SHydrogen sulfide + 2HCNHydrogen cyanide

General equation

Reaction of reducing species and reducible species: Reducing speciesReducing agent + Reducible speciesOxidizing agent
⟶
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of hydrogen and silver(I) thiocyanate

Reactants

Chemical formula	Name	Coefficient	Type	Type in general equation
H₂	Hydrogen	3	Reducing	Reducing
AgSCN	Silver(I) thiocyanate	2	Oxidizing	Reducible

Products

Chemical formula	Name	Coefficient	Type	Type in general equation
Ag	Silver	2	Reduced	–
H₂S	Hydrogen sulfide	2	Oxidized	–
HCN	Hydrogen cyanide	2	Redoxed product	–

Thermodynamic changes

Changes in standard condition

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −19.96 kJ/mol K 3.14 × 10³ pK −3.50: 3H₂Gas + 2AgSCNCrystalline solid
⟶
2AgCrystalline solid + 2H₂SGas + 2HCNLiquid

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	0.7	−19.96	68.3	48
per 1 mol of Hydrogen	0.23	−6.653	22.8	16
per 1 mol of Silver(I) thiocyanate	0.35	−9.980	34.1	24
per 1 mol of Silver	0.35	−9.980	34.1	24
per 1 mol of Hydrogen sulfide	0.35	−9.980	34.1	24
per 1 mol of Hydrogen cyanide	0.35	−9.980	34.1	24

Changes in aqueous solution (1)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −114.7 kJ/mol K 1.24 × 10²⁰ pK −20.09: 3H₂Un-ionized aqueous solution + 2AgSCNIonized aqueous solution
⟶
2AgCrystalline solid + 2H₂SGas + 2HCNIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−91.5	−114.7	−1480	–
per 1 mol of Hydrogen	−30.5	−38.23	−493.3	–
per 1 mol of Silver(I) thiocyanate	−45.8	−57.35	−740.0	–
per 1 mol of Silver	−45.8	−57.35	−740.0	–
per 1 mol of Hydrogen sulfide	−45.8	−57.35	−740.0	–
per 1 mol of Hydrogen cyanide	−45.8	−57.35	−740.0	–

Changes in aqueous solution (2)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −220.1 kJ/mol K 3.63 × 10³⁸ pK −38.56: 3H₂Un-ionized aqueous solution + 2AgSCNIonized aqueous solution
⟶
2AgCrystalline solid + 2H₂SGas + 2HCNUn-ionized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−178.5	−220.1	−1419	–
per 1 mol of Hydrogen	−59.50	−73.37	−473.0	–
per 1 mol of Silver(I) thiocyanate	−89.25	−110.0	−709.5	–
per 1 mol of Silver	−89.25	−110.0	−709.5	–
per 1 mol of Hydrogen sulfide	−89.25	−110.0	−709.5	–
per 1 mol of Hydrogen cyanide	−89.25	−110.0	−709.5	–

Changes in aqueous solution (3)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −103.3 kJ/mol K 1.25 × 10¹⁸ pK −18.10: 3H₂Un-ionized aqueous solution + 2AgSCNIonized aqueous solution
⟶
2AgCrystalline solid + 2H₂SUn-ionized aqueous solution + 2HCNIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−129.6	−103.3	−1650	–
per 1 mol of Hydrogen	−43.20	−34.43	−550.0	–
per 1 mol of Silver(I) thiocyanate	−64.80	−51.65	−825.0	–
per 1 mol of Silver	−64.80	−51.65	−825.0	–
per 1 mol of Hydrogen sulfide	−64.80	−51.65	−825.0	–
per 1 mol of Hydrogen cyanide	−64.80	−51.65	−825.0	–

Changes in aqueous solution (4)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −208.7 kJ/mol K 3.65 × 10³⁶ pK −36.56: 3H₂Un-ionized aqueous solution + 2AgSCNIonized aqueous solution
⟶
2AgCrystalline solid + 2H₂SUn-ionized aqueous solution + 2HCNUn-ionized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	−216.6	−208.7	−1589	–
per 1 mol of Hydrogen	−72.20	−69.57	−529.7	–
per 1 mol of Silver(I) thiocyanate	−108.3	−104.3	−794.5	–
per 1 mol of Silver	−108.3	−104.3	−794.5	–
per 1 mol of Hydrogen sulfide	−108.3	−104.3	−794.5	–
per 1 mol of Hydrogen cyanide	−108.3	−104.3	−794.5	–

Changes in aqueous solution (5)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −60.5 kJ/mol K 3.97 × 10¹⁰ pK −10.60: 3H₂Un-ionized aqueous solution + 2AgSCNUn-ionized aqueous solution
⟶
2AgCrystalline solid + 2H₂SGas + 2HCNIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	–	−60.5	–	–
per 1 mol of Hydrogen	–	−20.2	–	–
per 1 mol of Silver(I) thiocyanate	–	−30.3	–	–
per 1 mol of Silver	–	−30.3	–	–
per 1 mol of Hydrogen sulfide	–	−30.3	–	–
per 1 mol of Hydrogen cyanide	–	−30.3	–	–

Changes in aqueous solution (6)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −165.9 kJ/mol K 1.16 × 10²⁹ pK −29.06: 3H₂Un-ionized aqueous solution + 2AgSCNUn-ionized aqueous solution
⟶
2AgCrystalline solid + 2H₂SGas + 2HCNUn-ionized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	–	−165.9	–	–
per 1 mol of Hydrogen	–	−55.30	–	–
per 1 mol of Silver(I) thiocyanate	–	−82.95	–	–
per 1 mol of Silver	–	−82.95	–	–
per 1 mol of Hydrogen sulfide	–	−82.95	–	–
per 1 mol of Hydrogen cyanide	–	−82.95	–	–

Changes in aqueous solution (7)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −49.1 kJ/mol K 4.00 × 10⁸ pK −8.60: 3H₂Un-ionized aqueous solution + 2AgSCNUn-ionized aqueous solution
⟶
2AgCrystalline solid + 2H₂SUn-ionized aqueous solution + 2HCNIonized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	–	−49.1	–	–
per 1 mol of Hydrogen	–	−16.4	–	–
per 1 mol of Silver(I) thiocyanate	–	−24.6	–	–
per 1 mol of Silver	–	−24.6	–	–
per 1 mol of Hydrogen sulfide	–	−24.6	–	–
per 1 mol of Hydrogen cyanide	–	−24.6	–	–

Changes in aqueous solution (8)

Reaction of hydrogen and silver(I) thiocyanate ◆ Δ_rG −154.5 kJ/mol K 1.17 × 10²⁷ pK −27.07: 3H₂Un-ionized aqueous solution + 2AgSCNUn-ionized aqueous solution
⟶
2AgCrystalline solid + 2H₂SUn-ionized aqueous solution + 2HCNUn-ionized aqueous solution

	Standard enthalpy of reaction Δ_rH° kJ · mol⁻¹	Standard Gibbs energy of reaction Δ_rG° kJ · mol⁻¹	Standard entropy of reaction Δ_rS° J · K⁻¹ · mol⁻¹	Standard heat capacity of reaction at constant pressure Δ_rC_p° J · K⁻¹ · mol⁻¹
per 1 mol of Equation	–	−154.5	–	–
per 1 mol of Hydrogen	–	−51.50	–	–
per 1 mol of Silver(I) thiocyanate	–	−77.25	–	–
per 1 mol of Silver	–	−77.25	–	–
per 1 mol of Hydrogen sulfide	–	−77.25	–	–
per 1 mol of Hydrogen cyanide	–	−77.25	–	–

Thermodynamic data of reactants

Chemical formula	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
H₂ (g)	0^[1]	0^[1]	130.684^[1]	28.824^[1]
H₂ (ao)	-4.2^[1]	17.6^[1]	577^[1]	–
AgSCN (cr)	87.9^[1]	101.39^[1]	131.0^[1]	63^[1]
AgSCN (ai)	182.00^[1]	169.80^[1]	217.1^[1]	-18.4^[1]
AgSCN (ao)	–	142.7^[1]	–	–

* (g):Gas, (ao):Un-ionized aqueous solution, (cr):Crystalline solid, (ai):Ionized aqueous solution

Thermodynamic data of products

Chemical formula	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
Ag (cr)	0^[1]	0^[1]	42.55^[1]	25.351^[1]
Ag (g)	284.55^[1]	245.65^[1]	172.997^[1]	20.786^[1]
H₂S (g)	-20.63^[1]	-33.56^[1]	205.79^[1]	34.23^[1]
H₂S (ao)	-39.7^[1]	-27.83^[1]	121^[1]	–
HCN (l)	108.87^[1]	124.97^[1]	112.84^[1]	70.63^[1]
HCN (g)	135.1^[1]	124.7^[1]	201.78^[1]	35.86^[1]
HCN (ai)	150.6^[1]	172.4^[1]	94.1^[1]	–
HCN (ao)	107.1^[1]	119.7^[1]	124.7^[1]	–

* (cr):Crystalline solid, (g):Gas, (ao):Un-ionized aqueous solution, (l):Liquid, (ai):Ionized aqueous solution

References

List of references

1
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	−19.96 kJ/mol
K	3.14 × 10³
pK	−3.50

Δ_rG	−114.7 kJ/mol
K	1.24 × 10²⁰
pK	−20.09

Δ_rG	−220.1 kJ/mol
K	3.63 × 10³⁸
pK	−38.56

Δ_rG	−103.3 kJ/mol
K	1.25 × 10¹⁸
pK	−18.10

3H2 + 2AgSCN → 2Ag + 2H2S + 2HCN

Reaction data

Chemical equation

General equation

Oxidation state of each atom

Reactants

Products

Thermodynamic changes

Changes in standard condition

Changes in aqueous solution (1)

Changes in aqueous solution (2)

Changes in aqueous solution (3)

Changes in aqueous solution (4)

Changes in aqueous solution (5)

Changes in aqueous solution (6)

Changes in aqueous solution (7)

Changes in aqueous solution (8)

Thermodynamic data of reactants

Thermodynamic data of products

References

List of references

Related reactions

Reactions with same reactants

Related categories

Type of reaction

General equation

Reactant

Product

3H₂ + 2AgSCN → 2Ag + 2H₂S + 2HCN