DF

Question 1

exothermic reaction

Answer 1

reaction that gives out energy to the surroundings. delta H is - ve.
Energy released in making new bonds is greater than energy required to break existing bonds.

Question 2

endothermic reaction

Answer 2

reaction that takes in energy from and cools the surroundings. delta H is + ve.
Energy released in making new bonds is less than energy required to break existing bonds.

Question 3

standard conditions

Answer 3

298 K
1 atm pressure
1 mol dm-3 solutions

Question 4

standard enthalpy change of reaction

Answer 4

enthalpy change when molar quantities of reactants as stated in the equation react together under standard conditions.

Question 5

standard enthalpy change of combustion

Answer 5

enthalpy change when 1 mole of a substance is burnt completely in oxygen under standard conditions with elements in their standard states.

Question 6

standard enthalpy change of formation

Answer 6

enthalpy change when 1 mole of a compound is formed from its elements under standard conditions in standard states.

Question 7

standard enthalpy change of neutralisation

Answer 7

enthalpy change when 1 mole of H+ ions reacts with 1 mole of OH- ions to form 1 mole of water under standard conditions with 1 mol dm-3 solutions.

Question 8

converting from celcius to kelvin and kelvin to celcius:

Answer 8

+ 273

- 273

Question 9

aromatic compounds

Answer 9

compounds which contain 1 or more benzene rings

Question 10

aliphatic compounds

Answer 10

compounds which do not contain any benzene rings

Question 11

hydrocarbon

Answer 11

a compound formed of carbon and hydrogen atoms only

Question 12

functional group

Answer 12

a modifier responsible for the characteristic chemical reactions of molecules.

Question 13

saturated compound

Answer 13

hydrocarbons containing the maximum number of hydrogen atoms possible/ no C to C double or triple bonds.

Question 14

homologous series

Answer 14

a series of compounds which all have the same general molecular formula and functional group.

Question 15

average bond enthalpy

Answer 15

average quantity of energy required to break 1 mole of a bond with substances in the gaseous state. kJ mol-1

Question 16

cracking

example

Answer 16

any reaction in which a larger molecule is broken down into smaller molecules. E.g. cracking of alkanes to produce a shorter chain alkane and alkene.

Question 17

unsaturated compound

Answer 17

an organic compound which contains a double or triple bond between carbon atoms.

Question 18

catalyst

Answer 18

a substance which increases the rate of a chemical reaction but is chemically unchanged at the end.

Question 19

catalysis

Answer 19

the process of using a catalyst to increase the rate of a chemical reaction.

Question 20

heterogeneous catalyst

Answer 20

the catalyst and reactants are in different physical states.

Question 21

catalyst poison

how does it function?

Answer 21

stops a catalyst from functioning properly as it adsorbs to the catalyst surface more strongly than the reactants. The reactants are prevented from adsorbing and the catalyst is unable to get involved with the reaction.

Question 22

Process of heterogeneous catalysis

Answer 22

• reactant molecules adsorb to the catalyst surface.
• bonds within the reactant molecules weaken and break.
• new bonds form between the reactant atoms to form the products.
• the products desorb and diffuse away from the catalyst surface.

Question 23

enthalpy change of formation of an element = ?

Answer 23

0

Question 24

structural isomers

Answer 24

same molecular formula but different structural formula

Question 25

stereoisomers

Answer 25

same structural formula but a different arrangement of atoms in space.