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K2Cr2O7 + 2H2SO4 → 2KHSO4 + 2CrO3 + H2O

The reaction of potassium dichromate and sulfuric acid yields potassium hydrogensulfate, chromium(VI) oxide, and water (Other reactions are here). This reaction is an acid-base 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

Oxidation state of each atom

Reactants

Chemical formulaNameCoefficientTypeType in general
equation
K2Cr2O7Potassium dichromate1
Brønsted base
Salt of weak acid
H2SO4Sulfuric acid2
Brønsted acid
Strong acid

Products

Chemical formulaNameCoefficientTypeType in general
equation
KHSO4Potassium hydrogensulfate2
Conjugate base
Salt of strong acid
CrO3Chromium(VI) oxide2
Acidic oxide
H2OWater1
Conjugate acid
Water

Thermodynamic changes

Changes in standard condition

Reaction of potassium dichromate and sulfuric acid
K2Cr2O7Crystalline solid + 2H2SO4Liquid
2KHSO4Crystalline solid + 2CrO3Crystalline solid + H2OLiquid
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
−96.6
−96.6
per 1 mol of
−48.3
−48.3
per 1 mol of
−48.3
per 1 mol of
−96.6

Changes in aqueous solution

Reaction of potassium dichromate and sulfuric acid
K2Cr2O7Ionized aqueous solution + 2H2SO4Ionized aqueous solution
2KHSO4Ionized aqueous solution + 2CrO3Crystalline solid + H2OLiquid
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
69.2
69.2
per 1 mol of
34.6
34.6
per 1 mol of
34.6
per 1 mol of
69.2

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
K2Cr2O7 (cr)-2061.5[1]-1881.8[1]291.2[1]219.24[1]
K2Cr2O7 (ai)-1994.9[1]-1867.6[1]466.9[1]
H2SO4 (cr)
H2SO4 (l)-813.989[1]-690.003[1]156.904[1]138.91[1]
H2SO4 (ai)-909.27[1]-744.53[1]20.1[1]-293[1]
H2SO4 (l)
1 hydrate
-1127.621[1]-950.383[1]211.54[1]214.85[1]
H2SO4 (l)
2 hydrate
-1427.100[1]-1199.650[1]276.40[1]260.83[1]
H2SO4 (l)
3 hydrate
-1720.402[1]-1443.980[1]345.39[1]318.95[1]
H2SO4 (l)
4 hydrate
-2011.199[1]-1685.863[1]414.59[1]382.21[1]
H2SO4 (l)
6.5 hydrate
-2733.256[1]-2285.734[1]587.89[1]570.28[1]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (l):Liquid

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
KHSO4 (cr)-1160.6[1]-1031.3[1]138.1[1]
KHSO4 (ai)-1139.72[1]-1039.18[1]234.3[1]-63[1]
CrO3 (cr)-589.5[1]
CrO3 (g)-385.8[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, (ai):Ionized aqueous solution, (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)