A colour change in a reaction is a major detection point for analysis. Let us how this acid and base offer such colouration through the reaction.
Sulphuric acid is an analytical reagent existing mostly in aqueous forms due to high affinity towards water. Potassium dichromate is bright yellow solid famous in chemical industries but harmful on exposure to our skin. It is odourless,can be used to create dyes and even as a good indicator due to its bright colour.
In this article, we will examine how the reaction pans out to show products with different properties like reaction enthalpy and intermolecular forces.
What is the product of H2SO4 and K2CrO4?
H2SO4 and K2CrO4 are reacted to form Potassium dichromate, Potassium sulphate, and water respectively. The reaction equation is:
- 2K2CrO4 + H2SO4 → K2Cr2O7 + K2SO4 + H2O
What type of reaction is H2SO4 + K2CrO4?
The reaction of H2SO4 with K2CrO4 is a neutralisation reaction as an acid reacts with a base to form a neutral salt.
How to balance H2SO4 + K2CrO4?
The rules for balancing the chemical equation are as follows:
- K2CrO4 + H2SO4 → K2Cr2O7 + K2SO4 + H2O
- As both sides must be equalling in the number of atoms, keeping stoichiometry in mind, multiply K2CrO4 with 2 to equal with the Potassium atoms.
- 2K2CrO4 + H2SO4 → K2Cr2O7 + K2SO4 + H2O
H2SO4 + K2CrO4 Titration
The titration of HCl with K2CrO4 will yield significant results.
- Graduated burette
- Conical flask
- Volumetric flask
- Burette stand
Methyl Orange indicator is the suitable indicator for this acid-base titration. It turns acidic solution to nearly orange while turns to yellowish in basic solutions.
Titre and Titrant
- H2SO4 is used as the titrant which is added to the analyte.
- K2CrO4 is the analyte whose concentration is to be measured.
- K2CrO4 is weighed, added to the conical flask, and dissolved in water.
- The graduated burette is filled up with previously standardised H2SO4 and clamped to the stand.
- A few drops of Methyl Orange indicator are added to the solution.
- As the titration is carried out, an equivalence point is reached with a change in colour of the solution.
- Measurement of the concentration is carried out by the formula:
- VK2CrO4 SK2CrO4 = VH2SO4 SH2SO4
H2SO4 + K2CrO4 Net Ionic Equation
The net ionic equation is derived as:
- 4K+(aq) + 2CrO42-(aq) + 2H+(aq) +SO42-(aq) → 2K+(aq) +Cr2O72(aq) + 2K+(aq) + SO42-(aq)+ H+(aq)+ OH–(aq)
- Potassium chromate, a mild electrolyte, dissociate with Potassium and chromate ions.
- H2SO4, a strong electrolyte, dissociates into hydrogen and sulphate ions.
- K2Cr2O7, a mild electrolyte, dissociates into potassium and dichromate ions.
- Water forms its ionic form.
H2SO4 + K2CrO4 Conjugate Pairs
H2SO4 + K2CrO4 reactions’s conjugate pairs, which form when there is one proton difference between two compounds, are as follows: .
- Conjugate base of H2SO4= HSO4–
- Conjugate base of H2O= OH–
H2SO4 + K2CrO4 Intermolecular Forces
- Sulphuric acid can self-ionise and form H-bonding with the acidic proton.
- H2SO4 consists of strong ion-ion interactions.
- The chromate ion is tetrahedral in shape and has strong Van der Waals’ forces.
- There are two crystalline forms of K2CrO4.
H2SO4 + K2CrO4 Reaction Enthalpy
H2SO4 + K2CrO4 Reaction Enthalpy= +180.5 kJ/mol. Enthalpy information is as follows:
- Enthalpy of Formation of K2Cr2O7 = -2035 kJ/mol
- Enthalpy of Formation of H2SO4 = -814 kJ/mol
- Enthalpy of Formation of K2CrO4 = -1382 kJ/mol
- Enthalpy of Formation of H2O = -285.8 kJ/mol
- Enthalpy of Formation of K2SO4 = -1437.7 kJ/mol
Is H2SO4 + K2CrO4 a Buffer Solution?
K2CrO4 + H2SO4 can form a mild buffer solution because the weak base of chromate can neutralize the acid to an extent so that the pH of the solution gets maintained by the acid.
Is H2SO4 + K2CrO4 a Complete Reaction?
The H2SO4 + K2CrO4 reaction is complete as to the extent that the products formed at the reaction equilibirum.
Is H2SO4 + K2CrO4 an Endothermic Reaction?
H2SO4 + K2CrO4 reaction is endothermic with a positive enthalpy of reaction because the sulphuric acid solution needs some external energy to dissociate the chromate crystal.
Is H2SO4 + K2CrO4 a Redox Reaction?
The reaction of HCl and K2Cr2O7 is not an actual redox reaction as oxidation state of the atom does not get changed on the product side.
Is H2SO4 + K2CrO4 a Precipitation Reaction?
H2SO4 + K2CrO4 is not a precipitation reaction as the compounds are dried up to be obtained in solid form and do not reside as precipitates.
Is H2SO4 + K2CrO4 a Reversible Reaction?
H2SO4 + K2CrO4 reaction is reversible in nature as changing the conditions of an acid-base reaction can imply the backward the reaction.
Is H2SO4 + K2CrO4 a Displacement Reaction?
The reaction of sulphuric acid with Potassium chromate is not a double displacement reaction as the ions in the reactants do not get interchanged in the products.
The reaction of H2SO4 with K2CrO4 forms orange coloured potassium dichromate compound that is a common lab oxidising agent. Water soluble K2SO4 compound,used as a fertilizer, is also formed. Thus, the reaction serves as an acid-base titration with distinct colour change.