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These pellets become tacky in air because KOH is hygroscopic. Most commercial samples are ca. 90% pure, the remainder being water and carbonates. [11] Its dissolution in water is strongly exothermic. Concentrated aqueous solutions are sometimes called potassium lyes. Even at high temperatures, solid KOH does not dehydrate readily. [12]
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.
J.A. Dean (ed), Lange's Handbook of Chemistry (15th Edition), McGraw-Hill, 1999; Section 6, Thermodynamic Properties; Table 6.4, Heats of Fusion, Vaporization, and Sublimation and Specific Heat at Various Temperatures of the Elements and Inorganic Compounds
It is formed as potassium reacts with oxygen in the air, along with potassium oxide (K 2 O) and potassium superoxide (KO 2). Crystal structure. Potassium peroxide reacts with water to form potassium hydroxide and oxygen: 2 K 2 O 2 + 2 H 2 O → 4 KOH + O 2 ↑
The enthalpy of solution is most often expressed in kJ/mol at constant temperature. The energy change can be regarded as being made up of three parts: the endothermic breaking of bonds within the solute and within the solvent, and the formation of attractions between the solute and the solvent. An ideal solution has a null enthalpy of mixing.
Table of specific heat capacities at 25 °C (298 K) unless otherwise noted. [citation needed] Notable minima and maxima are shown in maroon. Substance Phase Isobaric mass heat capacity c P J⋅g −1 ⋅K −1 Molar heat capacity, C P,m and C V,m J⋅mol −1 ⋅K −1 Isobaric volumetric heat capacity C P,v J⋅cm −3 ⋅K −1 Isochoric ...
Std enthalpy of formation ... (KOH), in the presence of water, is ... The MnO 2 is fused with potassium hydroxide and heated in air or with another source ...
4 KO 2 + 4 CO 2 + 2 H 2 O → 4 KHCO 3 + 3 O 2. Theoretically, 1 kg of KO 2 absorbs 0.310 kg of CO 2 while releasing 0.338 kg of O 2. One mole of KO 2 absorbs 0.5 moles of CO 2 and releases 0.75 moles of oxygen. Potassium superoxide finds only niche uses as a laboratory reagent. Because it reacts with water, KO 2 is often studied in