Barium Hydroxide and Ammonium Thiocyanate (Endothermic)

Ba(OH)2·8H2O + 2NH4SCN → Ba(SCN)2 + 2NH3 + 10H2O

Overview

This highly endothermic acid-base reaction absorbs so much heat that it can freeze water beneath the flask. Mixing barium hydroxide octahydrate with ammonium thiocyanate drops the temperature below -20 C. The ammonium ion acts as a weak acid donating protons to hydroxide.

Participants

Role Substance Coefficient State
Product Ammonia NH₃ 2 (g)
Product Water H₂O 10 (l)

Everyday Example

This is one of the most dramatic endothermic reaction demonstrations, where a wet board freezes to a beaker as the reaction proceeds.

Industrial Importance

This reaction is primarily used as a teaching demonstration of endothermic processes and entropy-driven reactions, illustrating the thermodynamics concept that ΔG = ΔH - TΔS.

Properties

Type
Acid-Base
Reversible
No
Energy
Endothermic
ΔH
170.0 kJ/mol

Related Reactions

Acetic Acid and Sodium Acetate Buffer System Acetic Acid and Sodium Hydroxide Neutralization Acetic Acid Dissociation in Water Aluminum Chloride and Chloride Ion (Lewis Acid-Base) Aluminum Hydroxide as Amphoteric Acid with NaOH Aluminum Hydroxide as Amphoteric Base with HCl Ammonia and Ammonium Chloride Buffer System Ammonia and Hydrochloric Acid Ascorbic Acid and Sodium Hydroxide Benzoic Acid and Sodium Hydroxide

Frequently Asked Questions

What is the equation for Barium Hydroxide and Ammonium Thiocyanate (Endothermic)?
The balanced equation is: Ba(OH)₂·8H₂O + 2NH₄SCN → Ba(SCN)₂ + 2NH₃ + 10H₂O.
What type of reaction is Barium Hydroxide and Ammonium Thiocyanate (Endothermic)?
Barium Hydroxide and Ammonium Thiocyanate (Endothermic) is a acid-base reaction.
Is Barium Hydroxide and Ammonium Thiocyanate (Endothermic) exothermic or endothermic?
Barium Hydroxide and Ammonium Thiocyanate (Endothermic) is endothermic (absorbs energy). The enthalpy change (ΔH) is 170.0 kJ/mol.