Module 5 Definitions

Question 1

bronsted-lowry base

Answer 1

H+ acceptor

Question 2

bronsted-lowry acid

Answer 2

H+ donator

Question 3

alkali

Answer 3

soluble base that releases OH- ions

Question 4

salt

Answer 4

when the H+ in an acid is replaced by a metal or ammonium ion

Question 5

conjugate acid

Answer 5

a species formed when a proton is added to a base

Question 6

conjugate base

Answer 6

a species formed when a proton is removed from an acid

Question 7

conjugate acid-base pair

Answer 7

two species that differ by H+

Question 8

first ionisation energy

Answer 8

-The change in energy when one mole of electrons is removed from one mole of gaseous atoms to form one mole of gaseous 1+ ions
-positive enthalpy change as breaking the attraction between electron and proton

Question 9

First electron affinity

Answer 9

-The change in energy when one mole of gaseous atoms gain one mole of electrons to form one mole of gaseous 1- ions
-negative enthalpy change as forming a bond between electron and protons

Question 10

Second electron affinity

Answer 10

-The change in energy when one mole of gaseous 1- ions gain one mole of electrons to form one mole of gaseous 2- ions
-positive enthalpy change as overcome repulsion between negative ion and electron

Question 11

Standard enthalpy change of combustion

Answer 11

-The enthalpy change when one mole of a substance is completely burned in excess oxygen, under standard conditions
-negative enthalpy change as energy is released

Question 12

Standard enthalpy change of formation

Answer 12

-The enthalpy change when one mole of a compound is formed from it’s elements in the standard states, under standard conditions
-usually negative

Question 13

Standard enthalpy change of neutralisation

Answer 13

-The enthalpy change when an acid and an alkali are neutralised forming one mole of water, under standard conditions
-negative enthalpy change as making H2O

Question 14

Enthalpy change of atomisation

Answer 14

-The enthalpy change when one mole of gaseous atoms are formed from an element in it’s standard state
-positive enthalpy change as breaking a bond

Question 15

Lattice enthalpy

Answer 15

-The enthalpy change for the formation of one mole of an ionic compound from it’s gaseous ions under standard conditions
-negative enthalpy change as forming a bond

Question 16

Enthalpy change of hydration

Answer 16

-The enthalpy change when one mole of gaseous ions dissolve in water to form one mole of aqueous ions
-negative enthalpy change as bond formation with H2O

Question 17

Enthalpy change of solution

Answer 17

-The enthalpy change when one mole of a compound is completely dissolved in water
-positive or negative enthalpy change

Question 18

Standard enthalpy change of reaction

Answer 18

-The enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation with all reactants and products in their standard states, under standard conditions
-positive or negative enthalpy change

Question 19

average bond enthalpy

Answer 19

the enthalpy change for breaking one mole of bonds in gaseous molecules

Question 20

transition element

Answer 20

a d-block element that forms an ion with a partially filled d sub-shell

Question 21

ligand

Answer 21

a species that donates an electron pair to a metal ion and forms a dative covalent bond with the metal ion

Question 22

monodentate ligand

Answer 22

donates one lone pair of electrons to the central metal ion forming one dative bond

Question 23

bidentate ligand

Answer 23

donates two lone pairs of electrons to the central metal ion forming two dative bonds

Question 24

complex ion

Answer 24

an ion which is bonded to ligands

Question 25

co ordination number

Answer 25

the total number of dative covalent bonds between ligands and the central metal ion

Question 26

define entropy

Answer 26

-a measure of the degree of disorder in a system