K2Cr2O7 + 2HBr → 2KBr + 2CrO3 + H2O
Last updated:
The reaction of potassium dichromate and hydrogen bromide yields potassium bromide, chromium(VI) oxide, and water (Other reactions are here). This reaction is an acid-base reaction and is classified as follows:
Table of contents
Reaction data
Chemical equation
- Reaction of potassium dichromate and hydrogen bromide
General equation
- Salt of weak acidBrønsted base + Strong acidBrønsted acid ⟶ Salt of strong acidConjugate base + Acidic oxide + H2OConjugate acid
Oxidation state of each atom
- Reaction of potassium dichromate and hydrogen bromide
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| K2Cr2O7 | Potassium dichromate | 1 | Brønsted base | Salt of weak acid |
| HBr | Hydrogen bromide | 2 | Brønsted acid | Strong acid |
Products
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| KBr | Potassium bromide | 2 | Conjugate base | Salt of strong acid |
| CrO3 | Chromium(VI) oxide | 2 | – | Acidic oxide |
| H2O | Water | 1 | Conjugate acid | Water |
Thermodynamic changes
Changes in standard condition
- Reaction of potassium dichromate and hydrogen bromide
| 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 | −118.1 | – | – | – |
per 1 mol of | −118.1 | – | – | – |
per 1 mol of | −59.05 | – | – | – |
per 1 mol of | −59.05 | – | – | – |
per 1 mol of | −59.05 | – | – | – |
per 1 mol of | −118.1 | – | – | – |
Changes in aqueous solution
- Reaction of potassium dichromate and hydrogen bromide
| 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 | 25.3 | – | – | – |
per 1 mol of | 25.3 | – | – | – |
per 1 mol of | 12.7 | – | – | – |
per 1 mol of | 12.7 | – | – | – |
per 1 mol of | 12.7 | – | – | – |
per 1 mol of | 25.3 | – | – | – |
Thermodynamic data of reactants
| Chemical formula | Standard 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] | – |
| 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 formula | Standard 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] |
| 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, (g):Gas, (ai):Ionized aqueous solution, (l):Liquid
References
List of references
- 1Janiel J. Reed (1989)The NBS Tables of Chemical Thermodynamic Properties: Selected Values for Inorganic and C1 and C2 Organic Substances in SI UnitsNational Institute of Standards and Technology (NIST)
- ^ ΔfH°, -2061.5 kJ · mol−1
- ^ ΔfG°, -1881.8 kJ · mol−1
- ^ S°, 291.2 J · K−1 · mol−1
- ^ Cp°, 219.24 J · K−1 · mol−1
- ^ ΔfH°, -1994.9 kJ · mol−1
- ^ ΔfG°, -1867.6 kJ · mol−1
- ^ S°, 466.9 J · K−1 · mol−1
- ^ ΔfH°, -36.40 kJ · mol−1
- ^ ΔfG°, -53.45 kJ · mol−1
- ^ S°, 198.695 J · K−1 · mol−1
- ^ Cp°, 29.142 J · K−1 · mol−1
- ^ ΔfH°, -121.55 kJ · mol−1
- ^ ΔfG°, -103.96 kJ · mol−1
- ^ S°, 82.4 J · K−1 · mol−1
- ^ Cp°, -141.8 J · K−1 · mol−1
- ^ ΔfH°, -393.798 kJ · mol−1
- ^ ΔfG°, -380.66 kJ · mol−1
- ^ S°, 95.90 J · K−1 · mol−1
- ^ Cp°, 52.30 J · K−1 · mol−1
- ^ ΔfH°, -180.08 kJ · mol−1
- ^ ΔfG°, -212.96 kJ · mol−1
- ^ S°, 250.52 J · K−1 · mol−1
- ^ Cp°, 36.920 J · K−1 · mol−1
- ^ ΔfH°, -373.92 kJ · mol−1
- ^ ΔfG°, -387.23 kJ · mol−1
- ^ S°, 184.9 J · K−1 · mol−1
- ^ Cp°, -120.1 J · K−1 · mol−1
- ^ ΔfH°, -589.5 kJ · mol−1
- ^ ΔfH°, -385.8 kJ · mol−1
- ^ ΔfH°, -285.830 kJ · mol−1
- ^ ΔfG°, -237.129 kJ · mol−1
- ^ S°, 69.91 J · K−1 · mol−1
- ^ Cp°, 75.291 J · K−1 · mol−1
- ^ ΔfH°, -241.818 kJ · mol−1
- ^ ΔfG°, -228.572 kJ · mol−1
- ^ S°, 188.825 J · K−1 · mol−1
- ^ Cp°, 33.577 J · K−1 · mol−1