1. Mocks revision

Question 1

Methods of separation (physical):

Answer 1

1| Filtration – mixture poured through paper/porous material – liquid removed, solid remains
2| Dissolution (solvation) – mixture added to water/organic solvent – soluble substances removed, insoluble remain
3| Crystallization – mixture dissolved in hot water/organic solvent, solution cools down, crystals formed are filtered out – more soluble substances removed, less soluble remain
4| Evaporation (distillation) – mixture is heated up until one (/more) components evaporate – volatile liquids removed, solids/non-volatile liquids remain
5| Paper chromatography – mixture is placed on a piece of paper, one side of paper submerged in water/solvent, components move along the paper – more soluble components move faster (can be recognized)

Question 2

UV light has __ E/__ wavelength/__ frequency and IR light __ E/__ wavelength/__ frequency

Answer 2

high, short, high, low, long, low.

Question 3

use of radioisotopes

Answer 3

1) radiocarbon dating (C-14)
2) nuclear medicine (radiotherapy – Co-60)
3) medical tracing (SPECT imaging – iodine 125, iodine 131).

Question 4

steps in the mass spectrometer

Answer 4

1| Vaporization – turned into gas
2| Ionization – atoms turned into + ions
3| Acceleration – to achieve same Ek
4| Deflection – ions get deflected by a magnetic field according to their masses (and charges)
5| Detection – beam of ions passing through the screen gets detected electrically

Question 5

E =

Answer 5

hc/λ

Question 6

types of reactions

Answer 6

1) synthesis (combination)
2) decomposition
3) single-replacement reaction (A+BC->AC+B)
4) double-replacement reaction (AB+CD->AD+CB)
5) neutralization reaction
6) combustion reaction
7) polymerization

Question 7

three formulas for the number of moles

Answer 7

n=m/M
n=N/N_A
n= V^0/V^0_m

Question 8

C =

Answer 8

n/V

Question 9

ideal gas formula

Answer 9

pV=nRT

Question 10

gas constant
standard volume
Avogadro’s constant

Answer 10

R = 8.314 J/Kmol
V = 22.7dm3/mol
Na = 6,022 x 10 23 1/mol

Question 11

First, second, seventh and eight group names

Answer 11

alkali metals, alkaline earths, halogens, noble gases

Question 12

Metal vs nonmetal properties

Answer 12

atoms lose electrons (forming cations), good conductors of heat and electricity, malleable and ductile, have relatively high melting and boiling points
atoms gain electrons (form anions), insulators of heat and electricity, brittle solids, have relatively low melting and boiling points

Question 13

Metallic oxides vs nonmetallic oxides

Answer 13

high melting and boiling points, conduct electricity when molten (not when solid), and form basic solutions in reaction with water
variable malting and boiling points (SiO2’s very high, giant covalent structure), insulators, and form acidic solutions in reaction with water

Question 14

Trends in the periodic table and how do they change?

Answer 14

1| Atomic radius (increases down the group and to the left of a period)
2| Electron affinity
3| Ionization energy
4| Electronegativity (all increase up the group and to the right of a period)
5| Melting points no pattern across a period but for alkali it decreases down the group (with increasing atomic radius – metallic bonding) and for halogens it increases down the group (with increasing molar mass – covalent bonding)

Question 15

Electron affinity

Answer 15

a measure of the energy change when an electron is added to a neutral atom to form a negative ion
X (g) + e- -> X- (g) –

Question 16

Ionization energy

Answer 16

the energy required to remove one mole of electrons from one mole of isolated gaseous atom/ion
X (g) -> X+ (g) + e-

Question 17

Electronegativity

Answer 17

a chemical property that describes the ability of an atom to attract electrons toward itself in a covalent bond

Question 18

How does the size of ions change with their charge

Answer 18

cations<atoms<anions
the fewer electrons there are in an atom, the greater the attractive force on them – get pulled towards the nucleus more (also, a shell may be lost if all electrons get removed from it)

Question 19

How does reactivity (or oxidizing ability for halogens) change in alkali metals and halogens?

Answer 19

for alkali, it increases down the group, with increasing atomic radius, since they are metals they are prone to losing electrons and the further the electrons are from the nucleus (large radius) the easier it is for them to be lost and for the atom to react
for halogens, it decreases down the group, with increasing atomic radius, since they are nonmetals they are prone to gaining electrons and the further the valence shell is from the nucleus (large radius) the harder it is for the nucleus to attract new electrons and for the atom to react

Question 20

Examples of processes where transition metals act as catalysts

Answer 20

1| Haber process (Fe: N2 + 3 H2 ↔ 2 NH3)
2| Contact process (Vanadium (V) oxide: 2 SO2(g) + O2(g) ⇌ 2 SO3(g))
3| Hydrogenation reaction (Ni: C2H4 (g) + H2 (g) → C2H6)
4| Hydrogen peroxide breakdown (Manganese (IV) oxide: 2H2O2 (aq) → 2H2O (l) + O2 (g))