2.1

Question 1

definition of an ISOTOPE

Answer 1

Atoms of the SAME ELEMENT with same number of protons but DIFFERENT number of NEUTRONS

Question 2

definition of RELATIVE ISOTOPIC MASS

Answer 2

Mass of an isotope relative to 1/12th of the mass of an atom of CARBON-12

Question 3

definition of RELATIVE ATOMIC MASS

Answer 3

The weighted mean mass of an element to 1/12th the mass of an atom of CARBON-12

Question 4

how many atoms are in 1 mol?

Answer 4

1 mol = 6.02 x 10 to the 23 atoms

Question 5

Number of moles = ?

Answer 5

Moles = mass ➗ M (gmol-1)

Question 6

Concentration = ?

Answer 6

Conc = moles ➗ volume (dm3)

Question 7

Moles of gas = ?

Answer 7

Moles = volume ➗ 24

Question 8

Ideal gas equation

Answer 8

pV = nRT

Pa,m3 = mol,8.31,K

0 degrees = 273 K

Assume: random motion, elastic collisions, negligible size, no IM forces

Question 9

% yield = ?

Answer 9

% yield = actual yield ➗ theoretical yield

x100%

Question 10

Stoichiometry = ?

Answer 10

Ratios in an equation

e.g. 2H2 + O2 -> 2H2O = 2:1 ratio

Question 11

Atom economy = ?

Answer 11

Atom economy = sum of M of DESIRED products ➗ sum of M of ALL products

DESIRED ➗ ALL

Question 12

Strong acids

Answer 12

e.g. HCl

Fully dissociate

HCl (aq) -> H+ (aq) + Cl- (aq)

Question 13

Weak acids

Answer 13

e.g. CH3COOH

Partially dissociate

CH3COOH (aq) <> H+ (aq) + CH3COOH- (aq)

Question 14

Alkali = ?

Answer 14

Base that dissolves in water (releasing OH-)

Question 15

Base = ?

Answer 15

Neutralises acid to form a salt

Question 16

Dissociation in sulfuric acid

Answer 16

1. H2SO4 -> H+ (aq) + HSO4- (aq)

2.
HSO4- (aq) <> H+ (aq) + SO42- (aq)

First behaves as a strong acid, HSO4- ions behave as weak acid

Question 17

Neutralisation

Answer 17

Acid+base -> salt+water

e.g. HCl + NaOH -> NaCl + H2O
Ionic: H+ (aq) + OH- (aq) -> H2O (l)

Acid+carbonate -> salt+water+CO2

Question 18

Acid-base titrations

Answer 18

• Rough titration
• Mean titre (within 0.1cm3)

For:
Finding concentration of a solutions
Finding the purity of a substance
Identification of unknown chemicals

Question 19

Redox

Answer 19

Oxidation is loss of electrons
Reduction is gain of electrons

Oxidation = High oxidation no.
Reduction = Low oxidation no.

Question 20

Oxidation numbers

Answer 20

Oxidation no. =

• always 0 for elements in standard state
• +2,+3 etc for ions

Sum of oxidation numbers = total charge

If oxidised=reducing agent
If reduced=oxidising agent