Calorific value is the amount of heat energy released per unit mass or volume of a fuel completely burned. Common units: J/kg, kJ/kg, kcal/kg, Btu/lb. It indicates fuel quality. Hydrogen has ~142 MJ/kg.
Explanation:
Brass is an alloy of copper (Cu) and zinc (Zn). Proportions vary to give different properties; common brass is 70% Cu, 30% Zn. Bronze is primarily Cu and Sn (tin). Solder is Pb and Sn. Steel is Fe with C and other elements. Brass is used for musical instruments, plumbing, and decorative hardware due to its gold-like appearance and corrosion resistance.
Explanation:
Autocatalysis occurs when one of the products of a chemical reaction acts as a catalyst for that same reaction. As the reaction proceeds and the product accumulates, the rate of the reaction increases. A classic example is the oxidation of oxalic acid by potassium permanganate, where the Mn2+ ions produced catalyze the reaction.
Explanation:
Bleaching powder is calcium oxychloride, CaOCl₂. It is produced by passing chlorine over dry slaked lime: Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O. It is a mixed salt of Ca²⁺, Cl⁻, and OCl⁻ ions. It is used for bleaching and disinfection.
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