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4NH4SCN + 13HNO3 → 16HNO2 + NH4HSO4 + NH4HCO3 + 3HSCN

The reaction of ammonium thiocyanate and nitric acid yields nitrous acid, ammonium hydrogensulfate, ammonium hydrogencarbonate, and thiocyanic acid (Other reactions are here). This reaction is an oxidation-reduction reaction and is classified as follows:

Table of contents
  1. 1Reaction data
  2. 2Thermodynamic changes
  3. 3References
  4. 4Related reactions
  5. 5Related categories

Reaction data

Chemical equation

General equation

Reaction of reducing species and oxidizing species
Reducing speciesReducing agent + Oxidizing speciesOxidizing agent
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
NH4SCNAmmonium thiocyanate4
Reducing
Reducing
HNO3Nitric acid13
Oxidizing
Oxidizing

Products

Chemical formulaNameCoefficientTypeType in general
equation
HNO2Nitrous acid16
Redoxed product
NH4HSO4Ammonium hydrogensulfate1
Oxidized
NH4HCO3Ammonium hydrogencarbonate1
HSCNThiocyanic acid3

Thermodynamic changes

Changes in aqueous solution (1)

Reaction of ammonium thiocyanate and nitric acid
ΔrG−640.1 kJ/mol
K1.38 × 10112
pK−112.14
4NH4SCNIonized aqueous solution + 13HNO3Ionized aqueous solution
16HNO2Un-ionized aqueous solution + NH4HSO4Ionized aqueous solution + NH4HCO3Ionized aqueous solution + 3HSCNIonized aqueous solution
Standard enthalpy
of reaction
ΔrH°
kJ · mol−1
Standard
Gibbs energy
of reaction
ΔrG°
kJ · mol−1
Standard entropy
of reaction
ΔrS°
J · K−1 · mol−1
Standard heat
capacity of reaction
at constant pressure
ΔrCp°
J · K−1 · mol−1
per 1 mol of
Equation
−602.3−640.1118.3
−150.6−160.029.57
per 1 mol of
−46.33−49.249.100
per 1 mol of
−37.64−40.017.394
−602.3−640.1118.3
−602.3−640.1118.3
per 1 mol of
−200.8−213.439.43

Changes in aqueous solution (2)

Reaction of ammonium thiocyanate and nitric acid
ΔrG−625.6 kJ/mol
K3.98 × 10109
pK−109.60
4NH4SCNIonized aqueous solution + 13HNO3Ionized aqueous solution
16HNO2Un-ionized aqueous solution + NH4HSO4Ionized aqueous solution + NH4HCO3Ionized aqueous solution + 3HSCNUn-ionized aqueous solution
Standard enthalpy
of reaction
ΔrH°
kJ · mol−1
Standard
Gibbs energy
of reaction
ΔrG°
kJ · mol−1
Standard entropy
of reaction
ΔrS°
J · K−1 · mol−1
Standard heat
capacity of reaction
at constant pressure
ΔrCp°
J · K−1 · mol−1
per 1 mol of
Equation
−625.6
−156.4
per 1 mol of
−48.12
per 1 mol of
−39.10
−625.6
−625.6
per 1 mol of
−208.5

Changes in aqueous solution (3)

Reaction of ammonium thiocyanate and nitric acid
4NH4SCNIonized aqueous solution + 13HNO3Ionized aqueous solution
16HNO2Un-ionized aqueous solution + NH4HSO4Ionized aqueous solution + NH4HCO3Aqueous solution + 3HSCNIonized aqueous solution
Standard enthalpy
of reaction
ΔrH°
kJ · mol−1
Standard
Gibbs energy
of reaction
ΔrG°
kJ · mol−1
Standard entropy
of reaction
ΔrS°
J · K−1 · mol−1
Standard heat
capacity of reaction
at constant pressure
ΔrCp°
J · K−1 · mol−1
per 1 mol of
Equation
−599.5
−149.9
per 1 mol of
−46.12
per 1 mol of
−37.47
−599.5
−599.5
per 1 mol of
−199.8

Changes in aqueous solution (4)

Reaction of ammonium thiocyanate and nitric acid
4NH4SCNIonized aqueous solution + 13HNO3Ionized aqueous solution
16HNO2Un-ionized aqueous solution + NH4HSO4Ionized aqueous solution + NH4HCO3Aqueous solution + 3HSCNUn-ionized aqueous solution
Standard enthalpy
of reaction
ΔrH°
kJ · mol−1
Standard
Gibbs energy
of reaction
ΔrG°
kJ · mol−1
Standard entropy
of reaction
ΔrS°
J · K−1 · mol−1
Standard heat
capacity of reaction
at constant pressure
ΔrCp°
J · K−1 · mol−1
per 1 mol of
Equation
per 1 mol of
per 1 mol of
per 1 mol of

Thermodynamic data of reactants

Chemical formulaStandard enthalpy
of formation
ΔfH°
kJ · mol−1
Standard Gibbs
energy of
formation
ΔfG°
kJ · mol−1
Standard
molar entropy
S°
J · K−1 · mol−1
Standard molar
heat capacity at
constant pressure
Cp°
J · K−1 · mol−1
NH4SCN (cr)-78.7[1]
NH4SCN (ai)-56.07[1]13.40[1]257.7[1]39.7[1]
HNO3 (l)-174.10[1]-80.71[1]155.60[1]109.87[1]
HNO3 (g)-135.06[1]-74.72[1]266.38[1]53.35[1]
HNO3 (ai)-207.36[1]-111.25[1]146.4[1]-86.6[1]
HNO3 (l)
1 hydrate
-473.46[1]-328.77[1]216.90[1]182.46[1]
HNO3 (l)
3 hydrate
-1056.04[1]-811.09[1]346.98[1]325.14[1]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (l):Liquid, (g):Gas

Thermodynamic data of products

Chemical formulaStandard enthalpy
of formation
ΔfH°
kJ · mol−1
Standard Gibbs
energy of
formation
ΔfG°
kJ · mol−1
Standard
molar entropy
S°
J · K−1 · mol−1
Standard molar
heat capacity at
constant pressure
Cp°
J · K−1 · mol−1
HNO2 (g)
cis
-77.99[1]-42.94[1]248.76[1]44.77[1]
HNO2 (g)
trans
-80.12[1]-45.24[1]249.22[1]46.07[1]
HNO2 (g)-79.5[1]-46.0[1]254.1[1]45.6[1]
HNO2 (ao)-119.2[1]-50.6[1]135.6[1]
NH4HSO4 (cr)-1026.96[1]
NH4HSO4 (ai)-1019.85[1]-835.21[1]245.2[1]-3.8[1]
NH4HCO3 (cr)-849.4[1]-665.9[1]120.9[1]
NH4HCO3 (ai)-824.50[1]-666.07[1]204.6[1]
NH4HCO3 (aq)-821.7[1]
HSCN (ai)76.44[1]92.71[1]144.3[1]-40.2[1]
HSCN (ao)97.56[1]
* (g):Gas, (ao):Un-ionized aqueous solution, (cr):Crystalline solid, (ai):Ionized aqueous solution, (aq):Aqueous solution

References

List of references

  1. 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
    National Institute of Standards and Technology (NIST)