A complete A-Z dictionary of chemistry terms.
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Raoult’s Law Definition The pressure at which vapor is formed above a solid or liquid at a particular temperature is called the vapor pressure. Vapor and solid or liquid are in dynamic equilibrium at this temperature. In 1980s Rault discovered when a non-volatile solute is dissolved in a solvent the vapor pressure decreases. The lowering … Read more
Enthalpy Change Definition Enthalpy change is the heat change accompanying a chemical reaction at constant volume or constant pressure. The enthalpy change tells the amount of heat absorbed or evolved during the reaction. It is denoted by ΔH. Types of Enthalpy Change Enthalpy change of a reaction expressed in different ways depending on the nature … Read more
Arrhenius Equation Definition Generally we know that the increase of temperature of a reaction, the reaction rate increases. Normally the reaction rate is doubled by the increase of temperature by 10 oC. In 1989 Arrhenius suggested a simple relation between the reaction rate and the temperature of a reaction. The Arrhenius equation is written as: ……………………….(i) … Read more
Ideal Gas Law Definition The ideal gases obey the ideal gas law perfectly. This law states that: the volume of a given amount of gas is directly proportional to the number on moles of gas, directly proportional to the temperature and inversely proportional to the pressure. i.e. pV = nRT. The gas laws The volume … Read more
Equilibrium Constant Kp Definition When a reaction is at equilibrium, the forward and reverse reaction rate are same. The concentration of the reactants and products stay constant at equilibrium, even though the forward and backward reactions are still occurring. When one or more of the reactants or products are gas in any equilibrium reaction, the … Read more
Le Chatelier’s Principle Definition Le Chatlier’s principle is also known as “Chatelier’s principle” or “The Equilibrium Law”. Le Chatelier’s principle states that if a dynamic equilibrium is disturbed by changing the conditions (such as concentration, temperature and pressure changes) , the position of equilibrium shifts to counteract the change to reestablish an equilibrium. If a chemical … Read more