ENTHALPY CHANGES Flashcards
(25 cards)
What is exothermic reaction?
these are chemical reactions that release energy to the surrounding.
in exothermic reaction what increases
Temperature
The surroundings included during reactions are?
the solvent, air around the test tube, test tube itself, anything dipping in the test tube (thermometer)
examples of exothermic reactions are:
combustion of fuels, the oxidation of carbohydrates in the body of animals and plants, reaction of water with quick lime.
what is an endothermic reaction?
this is a chemical reaction that absorbs energy from the surrounding
in an endothermic reaction what decreases
Temperature
Examples of endothermic reactions include:
the decomposition of limestone by heating, photosynthesis( in which energy is supplied by sunlight), dissolving certain ammonium salts in water.
explain how the endothermic reaction is applied in the use of a cooling pack.
using a cooling pack to treat an injury when the pack is kneaded, water and ammonium chloride crystals dissolve, energy is transferred from the surroundings, cooling the injury.
Burning of magnesium in air is what type of reaction
exothermic reaction
the crystalization of coppper sulphate from a saturated solution is what type of reaction
endothermic reaction
fermentation of glucose by yeast is what type of reaction
exothermic reaction
what is the standard enthalpy change of formation?
this is the enthalpy change when one mole of a compound is formed from its elements under standard conditions.
what is the standard enthalpy change of combustion?
this is the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions.
what is the standard enthalpy change of combustion?
this is the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions.
what is the standard enthalpy change of neutralization
this is the enthalpy change when one mole of water is formed by the reaction of an acid with alkali under standard conditions.
standard enthalpy change of atomisation?
the enthalpy change when one mole of a gaseous atom is formed from its element under standard conditions.
standard enthalpy change of atomization?
the enthalpy change when one mole of a gaseous atom is formed from its element under standard conditions.
what is the standard enthalpy change of hydration of anhydrous salt?
enthalpy change when one mole of a hydrated salt is formed from one mole of the anhydrous salt under standard conditions.
state Hess’s law
states that the total enthalpy change for any chemical reaction is constant whether the reaction occurs in one step or in several steps as long as the initial and final conditions are the same
what is bond energy?
this is the amount of energy neeeded to break a specific amount of covalent bond .
what are the heat changes involved in born haber cycle?
heat of sublimation or atomisation, ionisation energy,elecron affinityand heat of dissociatiion
what is heat of atomisatiion
heat required to convert one mole of an atom from solid to gas.
what is heat of dissociation?
the heat required to produce one mole of a gaseous atom from a non metal
what is ionisation energy?
the amount of energy required to remove an electron from an isolated atom or molecule.
