ENTHALPY CHANGES

Question 1

What is exothermic reaction?

Answer 1

these are chemical reactions that release energy to the surrounding.

Question 2

in exothermic reaction what increases

Answer 2

Temperature

Question 3

The surroundings included during reactions are?

Answer 3

the solvent, air around the test tube, test tube itself, anything dipping in the test tube (thermometer)

Question 4

examples of exothermic reactions are:

Answer 4

combustion of fuels, the oxidation of carbohydrates in the body of animals and plants, reaction of water with quick lime.

Question 5

what is an endothermic reaction?

Answer 5

this is a chemical reaction that absorbs energy from the surrounding

Question 6

in an endothermic reaction what decreases

Answer 6

Temperature

Question 7

Examples of endothermic reactions include:

Answer 7

the decomposition of limestone by heating, photosynthesis( in which energy is supplied by sunlight), dissolving certain ammonium salts in water.

Question 8

explain how the endothermic reaction is applied in the use of a cooling pack.

Answer 8

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.

Question 9

Burning of magnesium in air is what type of reaction

Answer 9

exothermic reaction

Question 10

the crystalization of coppper sulphate from a saturated solution is what type of reaction

Answer 10

endothermic reaction

Question 11

fermentation of glucose by yeast is what type of reaction

Answer 11

exothermic reaction

Question 12

what is the standard enthalpy change of formation?

Answer 12

this is the enthalpy change when one mole of a compound is formed from its elements under standard conditions.

Question 13

what is the standard enthalpy change of combustion?

Answer 13

this is the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions.

Question 14

what is the standard enthalpy change of combustion?

Answer 14

this is the enthalpy change when one mole of a substance is burnt in excess oxygen under standard conditions.

Question 15

what is the standard enthalpy change of neutralization

Answer 15

this is the enthalpy change when one mole of water is formed by the reaction of an acid with alkali under standard conditions.

Question 16

standard enthalpy change of atomisation?

Answer 16

the enthalpy change when one mole of a gaseous atom is formed from its element under standard conditions.

Question 17

standard enthalpy change of atomization?

Answer 17

the enthalpy change when one mole of a gaseous atom is formed from its element under standard conditions.

Question 18

what is the standard enthalpy change of hydration of anhydrous salt?

Answer 18

enthalpy change when one mole of a hydrated salt is formed from one mole of the anhydrous salt under standard conditions.

Question 19

state Hess’s law

Answer 19

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

Question 20

what is bond energy?

Answer 20

this is the amount of energy neeeded to break a specific amount of covalent bond .

Question 21

what are the heat changes involved in born haber cycle?

Answer 21

heat of sublimation or atomisation, ionisation energy,elecron affinityand heat of dissociatiion

Question 22

what is heat of atomisatiion

Answer 22

heat required to convert one mole of an atom from solid to gas.

Question 23

what is heat of dissociation?

Answer 23

the heat required to produce one mole of a gaseous atom from a non metal

Question 24

what is ionisation energy?

Answer 24

the amount of energy required to remove an electron from an isolated atom or molecule.

Question 25

what is electron affinity?

Answer 25

energy released when one mole of a gaseous atom gains one mole of electrons