by Maryam Hussain How the working of a theoretical engine was proposed? The theoretical heat engine was proposed by Sadi Carnot in 1824 . Heat engines are devices that can convert heat into mechanical energy. Like a Steam engine or Motor vehicle, the working principle of all heat engines is the same in which any working substance gas or vapor is brought back to the initial stage by going through different thermodynamic stages of a cyclic process . Carnot suggested that, if a heat engine goes through fixed thermodynamic stages of a specified process, then the efficiency of the heat engine may be 100% possible. Ideally, this engine gives maximum efficiency. No other engine can be more efficient than this. The specified cyclic process suggested by Carnot is called the Carnot cycle. The Carnot engine has four main parts: 1). First, an insulated, non-conducting stand , so that the transfer of energy is not possible . 2). Second, a hot reservoir with infi...
by Maryam Hussain The heat of formation: The enthalpy of formation, also known as the heat of formation , of a compound is the heat involved in its formation from its constituent elements. The enthalpies of the formation of elements are assumed to be zero. Thus, for the special case of the heat reaction of a chemical reaction, the heat of formation, and enthalpies of each of the terms on the left-hand side of the chemical equation are zero, and the heat of reaction becomes equal to the heat of formation of the given compound. The standard heat of formation of a chemical compound is the enthalpy change when one g-mole of a specie at 25°C and 1 atm is formed from its elements in their naturally occurring states. Heats of formation of compounds are always expressed with reference to a standard state. The molal heat of the formation of a compound represents the heat of reaction, Δ o H f (kJ/mol), when 1 mole of the compound is formed from the elements in a reaction ...