(NH4)2Cr2O7 + 2HBr → 2NH4Br + H2Cr2O7
Last updated:
The reaction of ammonium dichromate and hydrogen bromide yields ammonium bromide and dichromic acid (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 ammonium dichromate and hydrogen bromide
General equation
- Salt of weak acidBrønsted base + Strong acidBrønsted acid ⟶ Salt of strong acidConjugate base + Weak acidConjugate acid
Oxidation state of each atom
- Reaction of ammonium dichromate and hydrogen bromide
Reactants
| Chemical formula | Name | Coefficient | Type | Type in general equation |
|---|---|---|---|---|
| (NH4)2Cr2O7 | Ammonium 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 |
|---|---|---|---|---|
| NH4Br | Ammonium bromide | 2 | Conjugate base | Salt of strong acid |
| H2Cr2O7 | Dichromic acid | 1 | Conjugate acid | Weak acid |
Thermodynamic changes
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 |
|---|---|---|---|---|
| (NH4)2Cr2O7 (cr) | -1806.7[1] | – | – | – |
| (NH4)2Cr2O7 (ai) | -1755.2[1] | -1459.5[1] | 488.7[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 |
|---|---|---|---|---|
| NH4Br (cr) | -270.83[1] | -175.2[1] | 113[1] | 96[1] |
| NH4Br (ai) | -254.05[1] | -183.26[1] | 195.8[1] | -61.9[1] |
| H2Cr2O7 | – | – | – | – |
* (cr):Crystalline solid, (ai):Ionized aqueous solution
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°, -1806.7 kJ · mol−1
- ^ ΔfH°, -1755.2 kJ · mol−1
- ^ ΔfG°, -1459.5 kJ · mol−1
- ^ S°, 488.7 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°, -270.83 kJ · mol−1
- ^ ΔfG°, -175.2 kJ · mol−1
- ^ S°, 113. J · K−1 · mol−1
- ^ Cp°, 96. J · K−1 · mol−1
- ^ ΔfH°, -254.05 kJ · mol−1
- ^ ΔfG°, -183.26 kJ · mol−1
- ^ S°, 195.8 J · K−1 · mol−1
- ^ Cp°, -61.9 J · K−1 · mol−1