2.1 Enthalpy

Question 1

exothermic reaction =

Answer 1

-releases energy
-increases in temperature
-negative delta H

Question 2

endothermic reaction =

Answer 2

-absorbs energy
-decreases in temperature
-positive delta H

Question 3

The principle of conservation of energy

Answer 3

Energy cannot be created or destroyed, only changed from one form to another

Question 4

what are standard conditions

Answer 4

-298k (25c)
-1atm pressure
-all substances in standard states
-conc: 1mol/dm^3

Question 5

what is ⦵

Answer 5

standard conditions

Question 6

unit for standard enthalpy change

Answer 6

kj/mol

Question 7

standard enthalpy change of combustion

Answer 7

enthalpy change when
-1mol of a substance undergoes complete combustion
-under standard conditions

Question 8

how to tell complete combustion has occured

Answer 8

products are just water and carbon dioxide

Question 9

Standard energy change of neutralisation

Answer 9

enthalpy change when
-1mol of water is formed
-in neutralisation reaction
-under standard conditions

Question 10

standard enthalpy change of formation

Answer 10

enthalpy change when
-one mole of a compound is formed from its elements
-under standard conditions
-all chemicals in standard states

Question 11

standard enthalpy change of reaction

Answer 11

-between the number of moles of reactants shown in the equation for the reaction

Question 12

standard enthalpy change of combustion FORMULA

Answer 12

energy change of water(j) = m(g of water) c at

Question 13

state hess’s law

Answer 13

total enthalpy change for a reaction is independent of the root taken from the reactants to the products