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4B + 6HNO3 → 2B2O3 + 3N2O3↑ + 3H2O

The reaction of boron and nitric acid yields diboron trioxide, dinitrogen trioxide, 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 reducing species and oxidizing species
Reducing speciesReducing agent + Oxidizing speciesOxidizing agent
ProductOxidation product + ProductReduction product

Oxidation state of each atom

Reaction of boron and nitric acid

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
BBoron4
Reducing
Reducing
HNO3Nitric acid6
Oxidizing
Oxidizing

Products

Chemical formulaNameCoefficientTypeType in general
equation
B2O3Diboron trioxide2
Oxidized
N2O3Dinitrogen trioxide3
Reduced
H2OWater3

Thermodynamic changes

Changes in standard condition (1)

Reaction of boron and nitric acid
ΔrG−2196.05 kJ/mol
K5.39 × 10384
pK−384.73
4BCrystalline solid + 6HNO3Liquid
2B2O3Crystalline solid + 3N2O3Gas + 3H2OLiquid
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
−2107.27−2196.05297.47−155.02
per 1 mol of
−526.817−549.01374.368−38.755
per 1 mol of
−351.212−366.00849.578−25.837
per 1 mol of
−1053.63−1098.03148.74−77.510
−702.423−732.01799.157−51.673
per 1 mol of
−702.423−732.01799.157−51.673

Changes in standard condition (2)

Reaction of boron and nitric acid
ΔrG−2173.3 kJ/mol
K5.57 × 10380
pK−380.75
4BCrystalline solid + 6HNO3Liquid
2B2O3Amorphous solid + 3N2O3Gas + 3H2OLiquid
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
−2070.79−2173.3345.1−158.7
per 1 mol of
−517.697−543.3386.28−39.67
per 1 mol of
−345.132−362.2257.52−26.45
per 1 mol of
−1035.39−1086.7172.6−79.35
−690.263−724.43115.0−52.90
per 1 mol of
−690.263−724.43115.0−52.90

Changes in standard condition (3)

Reaction of boron and nitric acid
4BAmorphous solidx denotes undetermined zero point entropy + 6HNO3Liquid
2B2O3Crystalline solid + 3N2O3Gas + 3H2OLiquid
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
−2122.5327.44−158.54
per 1 mol of
−530.6381.860−39.635
per 1 mol of
−353.7554.573−26.423
per 1 mol of
−1061.3163.72−79.270
−707.50109.15−52.847
per 1 mol of
−707.50109.15−52.847

Changes in standard condition (4)

Reaction of boron and nitric acid
4BAmorphous solidx denotes undetermined zero point entropy + 6HNO3Liquid
2B2O3Amorphous solid + 3N2O3Gas + 3H2OLiquid
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
−2086.0375.1−162.2
per 1 mol of
−521.5093.78−40.55
per 1 mol of
−347.6762.52−27.03
per 1 mol of
−1043.0187.6−81.10
−695.33125.0−54.07
per 1 mol of
−695.33125.0−54.07

Changes in aqueous solution

Reaction of boron and nitric acid
ΔrG−2012.81 kJ/mol
K4.26 × 10352
pK−352.63
4BCrystalline solid + 6HNO3Ionized aqueous solution
2B2O3Crystalline solid + 3N2O3Gas + 3H2OLiquid
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
−1907.71−2012.81352.71023.8
per 1 mol of
−476.928−503.20288.17255.95
per 1 mol of
−317.952−335.46858.78170.63
per 1 mol of
−953.855−1006.40176.3511.90
−635.903−670.937117.6341.27
per 1 mol of
−635.903−670.937117.6341.27

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
B (cr)0[1]0[1]5.86[1]11.09[1]
B (am)
x denotes undetermined zero point entropy
3.8[1]6.53+x[1]11.97[1]
B (g)562.7[1]518.8[1]153.45[1]20.799[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, (am):Amorphous 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
B2O3 (cr)-1272.77[1]-1193.65[1]53.97[1]62.93[1]
B2O3 (am)-1254.53[1]-1182.3[1]77.8[1]61.1[1]
B2O3 (g)-843.79[1]-831.97[1]279.81[1]66.86[1]
N2O3 (l)50.29[1]
N2O3 (g)83.72[1]139.46[1]312.28[1]65.61[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]
* (cr):Crystalline solid, (am):Amorphous solid, (g):Gas, (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)