15 Facts on H2SO4 + K2CrO4: What, How To Balance & FAQs

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.

Apparatus

• Graduated burette
• Conical flask
• Volumetric flask
• Burette stand

Indicator

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.

Procedure 

• 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:
• V_K2CrO4 S_K2CrO4 = V_H2SO4 S_H2SO4

H₂SO₄ + K₂CrO₄ Net Ionic Equation

The net ionic equation is derived as:

• 4K⁺(aq) +  2CrO₄^2-(aq) + 2H⁺(aq) +SO₄^2-(aq) → 2K⁺(aq) +Cr₂O₇²(aq) + 2K⁺(aq) + SO₄^2-(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 K₂CrO_4­.            

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.

Conclusion

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.

Neeloy Bhattacharya

Hello….Neeloy here! I have pursued a Master’ in Chemistry and am currently a Subject Matter Expert in this community. Science and reasoning feed my curiosity and I love to express whatever I see, in my words. Quiz addict. Let’s connect at LinkedIn.