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Au + HNO3 + 4HCl → H[AuCl4] + NO + 2H2O

The reaction of gold, nitric acid, and hydrogen chloride yields tetrachloridoauric(III) acid, nitrogen monoxide, and water (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 inactive metal and aqua regia
Inactive metalReducing agent + HNO3Oxidizing agent + HCl
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of gold and aqua regia

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
AuGold1
Reducing
Inactive metal
HNO3Nitric acid1
Oxidizing
Nitric acid
HClHydrogen chloride4
Hydrogen chloride

Products

Chemical formulaNameCoefficientTypeType in general
equation
H[AuCl4]Tetrachloridoauric(III) acid1
Oxidized
NONitrogen monoxide1
Reduced
H2OWater2

Thermodynamic changes

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
Au (cr)0[1]0[1]47.40[1]25.418[1]
Au (g)366.1[1]326.3[1]180.503[1]20.786[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]
HCl (g)-92.307[1]-95.299[1]186.908[1]29.12[1]
HCl (ai)-167.159[1]-131.228[1]56.5[1]-136.4[1]
* (cr):Crystalline solid, (g):Gas, (l):Liquid, (ai):Ionized aqueous solution

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
H[AuCl4]
NO (g)90.25[1]86.55[1]210.761[1]29.844[1]
H2O (cr)
H2O (l)-285.830[1]-237.129[1]69.91[1]75.291[1]
H2O (g)-241.818[1]-228.572[1]188.825[1]33.577[1]
* (g):Gas, (cr):Crystalline solid, (l):Liquid

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)