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K2SO3 + 2HBr → 2KBr + SO2 + H2O

The reaction of potassium sulfite and hydrogen bromide yields potassium bromide, sulfur dioxide, 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
K2SO3Potassium sulfite1
Brønsted base
Salt of weak acid
HBrHydrogen bromide2
Brønsted acid
Strong acid

Products

Chemical formulaNameCoefficientTypeType in general
equation
KBrPotassium bromide2
Conjugate base
Salt of strong acid
SO2Sulfur dioxide1
Acidic oxide
H2OWater1
Conjugate acid
Water

Thermodynamic changes

Changes in standard condition

Reaction of potassium sulfite and hydrogen bromide
K2SO3Crystalline solid + 2HBrGas
2KBrCrystalline solid + SO2Gas + 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
−172.0
per 1 mol of
−172.0
per 1 mol of
−86.00
per 1 mol of
−86.00
per 1 mol of
−172.0
per 1 mol of
−172.0

Changes in aqueous solution (1)

Reaction of potassium sulfite and hydrogen bromide
ΔrG−50.8 kJ/mol
K7.94 × 108
pK−8.90
K2SO3Ionized aqueous solution + 2HBrIonized aqueous solution
2KBrIonized aqueous solution + SO2Gas + 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
52.7−50.8347
per 1 mol of
52.7−50.8347
per 1 mol of
26.4−25.4174
per 1 mol of
26.4−25.4174
per 1 mol of
52.7−50.8347
per 1 mol of
52.7−50.8347

Changes in aqueous solution (2)

Reaction of potassium sulfite and hydrogen bromide
ΔrG−51.2 kJ/mol
K9.33 × 108
pK−8.97
K2SO3Ionized aqueous solution + 2HBrIonized aqueous solution
2KBrIonized aqueous solution + SO2Un-ionized aqueous solution + 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
26.5−51.2261
per 1 mol of
26.5−51.2261
per 1 mol of
13.3−25.6131
per 1 mol of
13.3−25.6131
per 1 mol of
26.5−51.2261
per 1 mol of
26.5−51.2261

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
K2SO3 (cr)-1125.5[1]
K2SO3 (ai)-1140.1[1]-1053.1[1]176[1]
HBr (g)-36.40[1]-53.45[1]198.695[1]29.142[1]
HBr (ai)-121.55[1]-103.96[1]82.4[1]-141.8[1]
* (cr):Crystalline solid, (ai):Ionized aqueous solution, (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
KBr (cr)-393.798[1]-380.66[1]95.90[1]52.30[1]
KBr (g)-180.08[1]-212.96[1]250.52[1]36.920[1]
KBr (ai)-373.92[1]-387.23[1]184.9[1]-120.1[1]
SO2 (l)-320.5[1]
SO2 (g)-296.830[1]-300.194[1]248.22[1]39.87[1]
SO2 (ao)-322.980[1]-300.676[1]161.9[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, (g):Gas, (ai):Ionized aqueous solution, (l):Liquid, (ao):Un-ionized 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)