Thermochemistry

Question 1

Standard enthalpy change of reaction

Answer 1

Amount of energy absorbed or released in a chemical reaction when the molar quantities of reactants specified in the chemical equation react under standard conditions.

Question 2

Standard enthalpy change of combustion

Answer 2

Amount of energy released in a chemical reaction when one mole of the substance is completely burnt in oxygen under standard conditions (25dgC, 1atm)

Question 3

Standard enthalpy change of neutralisation

Answer 3

Between an acid and alkali is the energy released when one mole of water is formed from the neutralisation of acid and alkali under standard conditions (25dgC, 1atm)

Question 4

Standard enthalpy change of formation

Answer 4

Of a substance is the energy absorbed or released when one mole of the substance is formed from its elements under standard conditions (25dgC, 1atm)

Question 5

Bond energy of X-Y bond (BE (X-Y))

Answer 5

Is the average energy absorbed when one mole of X-Y bonds is broken in the gaseous state to form X and Y gaseous atoms.

Question 6

Bond dissociation energy

Answer 6

Of a X-Y bond is the energy absorbed to break one mole of that particular X-Y bond in the gaseous state in a particular compound.

Question 7

Standard enthalpy change of atomisation

Answer 7

Of an element is the energy absorbed when one mole of gaseous atoms is formed from the element under standard conditions (25dgC, 1atm)

Question 8

Standard enthalpy change of atomisation of a compound

Answer 8

Is the enthalpy change when one mole of the compound is converted into its constituent gaseous atoms under standard conditions

Question 9

First ionisation energy (1st I.E.) of an element

Answer 9

Is the energy absorbed when one mole of gaseous atoms lose one mole of electrons to give one mole of singly charged positive gaseous ions.

Question 10

Second ionisation energy (2nd I.E.) of an element

Answer 10

Is the energy absorbed when one mole of singly charged positive gaseous ions lose one mole of electrons to give one mole of doubly charged positive gaseous ions.

Question 11

First electron affinity (1st E.A.)

Answer 11

Of an element is the energy released when one mole of gaseous atoms acquire one mole of electrons to give one mole of singly charged negative gaseous ions.

Question 12

Second electron affinity (2nd E.A.)

Answer 12

Of an element is the energy absorbed when one mole of singly charged negative gaseous ions acquire one mole of electrons to give one mole of doubly charged negative gaseous ions.

Question 13

Lattice energy of an ionic crystal

Answer 13

is the energy released when one mole of the ionic compound is formed from its constituent gaseous ions under standard conditions (25dgC, 1atm)

Question 14

Standard enthalpy change of hydration of an ion

Answer 14

Is the energy released when one mole of the gaseous ion is hydrated to form an infinitely dilute solution under standard conditions (25dgC, 1atm)

Question 15

Standard enthalpy change of solution of a substance

Answer 15

Is the energy absorbed or released when one mole of the substance is completely dissolved in a solvent to form an infinitely dilute solution under standard conditions (25dgC, 1atm)