The oxidation number of an atom is a number that represents the total number of electrons lost or gained by it. It describes the degree of oxidation of an atom in a chemical compound. It has been developed to keep track of electron shifts in chemical reactions involving formation of covalent compounds. In this method the … Read more

  The reactions in which the oxidation states of atoms are changed are known as Redox reactions. They are characterized by transfer of electrons. The chemical species in which the electron is added is said to have been reduced, while the chemical species from which the electron is subtracted is said to have been oxidized. … Read more

  Great care should be ensured before preparing and collecting the hydrogen gas. It should be kept in mind that the removal of air from the apparatus is a foremost important step as the mixture of hydrogen with the air is highly explosive. How Granulated Zinc is Used to Make Hydrogen In the laboratory, hydrogen … Read more

Hydrogen peroxide’s discovery was done by a French chemist J.L.Thenard. We write molecular formula of hydrogen peroxide as . Preparation of Hydrogen peroxide: Hydrogen peroxide can be prepared in the laboratory by the action of cold, dilute sulphuric acid on sodium or barium peroxide. Let’s have a look at each of them one by one: … Read more

Fuels burn to release a large amount of energy. The energy is released by the combustion of some fuels such as dihydrogen, methane, LPG, and gasoline. Here we are going to talk about hydrogen as a fuel. Dihydrogen releases about three times more energy than gasoline on combustion. Also, the pollutants in the combustion of … Read more

Chemical Thermodynamics: Standard enthalpy of formation The standard enthalpy of formation (ΔHf°) for a reaction is the enthalpy change that occurs when 1 mol of a substance is formed from its component elements in their standard states. When we say “The standard enthalpy of formation of methanol, CH3OH(l) is –238.7 kJ”, it means: C(graphite) + … Read more

Chemical thermodynamics: Standard Enthalpy of Combustion Combustion is a chemical reaction that occurs between any fuel and oxygen. Heat energy is produced from the combustion of a fuel with air. The internal energy of the fuel species is their chemical energy. This energy corresponds to the chemical bonds and intermolecular attractions. During a chemical reaction, … Read more

Chemical Thermodynamics: Enthalpy of bond dissociation Bond enthalpy can be used to calculate unknown enthalpy changes for a reaction. However, there are limitations to the results of these calculations as they are based on average bond enthalpies (i.e. typical values for a bond) and only valid gaseous reactants AND products The bond dissociation enthalpy/energy (BDE) … Read more

Chemical Thermodynamics: Hess’s Law of constant heat summation Hess’s Law of Constant Heat Summation states that the total enthalpy of a chemical reaction can be depicted as the sum of the enthalpy changes for the steps of the reaction. Therefore, you can find enthalpy change by breaking a reaction into component steps that have known … Read more

Chemical Thermodynamics: Measurement of Internal energy change, δU and enthalpy, ΔH Heat capacity is the measurable physical quantity that characterizes the amount of heat required to change a substance’s temperature by a given amount Calorimeter is a device for measuring the heat produced during an electrical, mechanical or chemical reaction, and for calculating the heat … Read more