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Potassium persulfate can be prepared by electrolysis of a cold solution potassium bisulfate in sulfuric acid at a high current density. [1] [4]2 KHSO 4 → K 2 S 2 O 8 + H 2. It can also be prepared by adding potassium bisulfate (KHSO 4) to a solution of the more soluble salt ammonium peroxydisulfate (NH 4) 2 S 2 O 8.
Enthalpy change of solution in water at 25 °C for some selected compounds [2] Compound ΔH o in kJ/mol; hydrochloric acid: −74.84 ammonium nitrate +25.69 ammonia: −30.50 potassium hydroxide: −57.61 caesium hydroxide: −71.55 sodium chloride +3.87 potassium chlorate +41.38 acetic acid: −1.51 sodium hydroxide: −44.50
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
Potassium sulfate (K 2 SO 4) has been known since early in the 14th century.It was studied by Glauber, Boyle, and Tachenius.In the 17th century, it was named arcanuni or sal duplicatum, as it was a combination of an acid salt with an alkaline salt.
K 2 SO 4 + 4 C → K 2 S + 4 CO. In the laboratory, pure K 2 S may be prepared by the reaction of potassium and sulfur in anhydrous ammonia. [4] Sulfide is highly basic, consequently K 2 S completely and irreversibly hydrolyzes in water according to the following equation: K 2 S + H 2 O → KOH + KSH. For many purposes, this reaction is ...
For example, the standard enthalpy of combustion of ethane gas refers to the reaction C 2 H 6 (g) + (7/2) O 2 (g) → 2 CO 2 (g) + 3 H 2 O (l). Standard enthalpy of formation is the enthalpy change when one mole of any compound is formed from its constituent elements in their standard states.
The relevant conversion is the exothermic reaction of potassium chloride and sulfuric acid: [1] [2] KCl + H 2 SO 4 → HCl + KHSO 4. Potassium bisulfate is a by-product in the production of nitric acid from potassium nitrate and sulfuric acid: [3] KNO 3 + H 2 SO 4 → KHSO 4 + HNO 3
For gases, departure from 3 R per mole of atoms is generally due to two factors: (1) failure of the higher quantum-energy-spaced vibration modes in gas molecules to be excited at room temperature, and (2) loss of potential energy degree of freedom for small gas molecules, simply because most of their atoms are not bonded maximally in space to ...