Notes and Study material for Exams
Preparation of hydrogen Hydrogen is the most abundant element in the universe. The sun and other stars are composed largely of hydrogen. Astronomers estimate that 90% of the atoms in the universe are hydrogen atoms. Hydrogen is a component of more compounds than any other element. Water is the most abundant compound of hydrogen found … Read more
Preparation of Oxygen Oxygen is prepared in lab generally in two ways either by the application of heat or no application of heat. Using heat: Oxygen in lab is prepared by heating the mixture of powdered potassium chlorate and manganese dioxide in the ratio 4:1 in a hard glass test tube. The oxygen gas is … Read more
Endothermic Reactions Endothermic reactions are those chemical reactions where energy is absorbed by the system from the surroundings mostly in the form of heat. The concept is applied in the physical sciences like chemical reactions where hear is converted to chemical bond energy by way of experiments. Common examples of endothermic reactions are cooking an … Read more
Acid An acid is a substance which forms H+ ions as the only positive ion in aqueous solution. Examples:- Hydrochloric acid dissolved in water forms H+ and Cl– ions HCl —> H+ + Cl– Sulphuric acid dissolved in water forms H+ and SO42- ions H2SO4 —>2H+ + SO42- Nitric acid forms H+ and NO3– ions when dissolved in water … Read more
What is a Fuel Cell? A fuel cell is an electrochemical device that converts chemical energy from a fuel into electrical energy and heat. Fuel cells are similar to batteries in that they both convert chemical energy into electrical energy, but fuel cells do not run down and need to be recharged. Instead, they can … Read more