past paper stuff

Question 1

how do London forces arise ???

Answer 1

• uneven distribution of electrons
• creates instantaneous (temporary) dipole
• dipole is induced

Question 2

what is the name given to repeating pattern of properties along a period ?

Answer 2

periodicity

Question 3

what to remember with all calculations ?

Answer 3

does it ask for sig figs / decimal places ??

Question 4

what does xH2O represent ?

Answer 4

water of crystallisation

Question 5

what is a salt ?

Answer 5

metal /ammonium ion replaces H+ ion in an acid

Question 6

define dative covalent bond

Answer 6

both electrons donated from same atom

Question 7

define isotope

Answer 7

atoms of an element with same no of protons, diff no of neutrons

Question 8

why do isotopes have similar chemical properties ?

Answer 8

same no. of electrons in outer shell

Question 9

what to remember when drawing H bonds

Answer 9

lone pairs on Oxygen

Question 10

what are conditions needed to make bleach ?

Answer 10

cold dilute NaOH

Question 11

what is the 2nd product of metal + water/acid ?

Answer 11

hydrogen

Question 12

what is meant by ionic lattice ?

Answer 12

repeating pattern of oppositely charged ions

Question 13

pV =

Answer 13

nRT

Question 14

what are the units of pressure in pV =

Answer 14

Pa

Question 15

what are the units of volume in pV =

Answer 15

m3

Question 16

what are the units of temp in pV =

Answer 16

kelvin

Question 17

what is R in pV=

Answer 17

8.314 J / K / mol

Question 18

what does roman numerals show

Answer 18

oxidation number

Question 19

state two methods of carbon capture and storage

Answer 19

• react with metal oxide to for metal carbonate

- deep in ocean

Question 20

what are (2) factors of greenhouse effect of a gas ?

Answer 20

• abundance

- ability to absorb IR

Question 21

to be soluble in water, molecule must be able to …

Answer 21

form H-bonds with water

Question 22

what is the oxidation of alcohols observation ?

Answer 22

orange to green

Question 23

give two reasons why radical substitution produces a mixture of organic products

Answer 23

• further substitution

- substitution at diff positions along chain

Question 24

give two reasons why enthalpy change of combustion isn’t very accurate

Answer 24

• incomplete combustion may occur

- water / alcohol may evaporate

Question 25

when describe IR spectroscopy... what to remember

Answer 25

- IR absorbance at ... | - no absorbance at ...

Question 26

what is a Brownsted-Lowry acid?

Answer 26

proton donor

Question 27

what observation for phenol + bromine ?

Answer 27

- decolourises | - white ppt forms

Question 28

what gets oxidised and reduced in disproportionation ?

Answer 28

ELEMENT

Question 29

what are the conditions for formation of bleach ?

Answer 29

cold dilute (NaOH)

Question 30

suggest two reasons for why radical sub produces many products

Answer 30

- further sub | - sub at diff positions on chain

Question 31

what are two factors of greenhouse effect of gas ?

Answer 31

- conc | - ability to absorb IR

Question 32

state a biodegradable alternative for CFCs

Answer 32

hydrocarbon

Question 33

what is co solvent for testing for halides ?

Answer 33

warm ethanol

Question 34

What name is given to the process by which components in a mixture are separated during gas/liquid chromatography?

Answer 34

Partition

Question 35

define average bond enthalpy

Answer 35

energy required to break 1 mol of bonds in gaseous molecules

Question 36

what to remember w/ rate constant ?

Answer 36

UNITS

Question 37

when forming mechanism for rate determining step thing, what must you not do ?

Answer 37

no intermediate electrons

Question 38

state two advantages of fuel cells compared w/ fossil fuel combustion

Answer 38

- more efficient | - less CO2

Question 39

why is benzoic acid less reactive than benzene ?

Answer 39

COOH is electron withdrawing group, so decreases electron density

Question 40

how is conc of ozone maintained ?

Answer 40

O2 + O -- O3 O3 -- O2 + O rate of O3 decomp = O3 formation

Question 41

state a disadvantage (apart from storage) of hydrogen fuel for fuel cell

Answer 41

hydrogen is explosive

Question 42

state a important difference between electrochemical and fuel cell

Answer 42

fuel cell requires constant fuel supply

Question 43

suggest why some people think use of hydrogen as fuel consumes more energy than fossil fuels

Answer 43

energy needed to make hydrogen

Question 44

what is the important factor when choosing suitable indicator ?

Answer 44

equivalence point matches pH range of indicator

Question 45

define relative atomic mass

Answer 45

weighted mean mass of an ATOM compared w/ 1/12th mass of carbon-12

Question 46

define electronegativity

Answer 46

ability of an atom to attract electrons in a covalent bond

Question 47

define covalent bond

Answer 47

strong electrostatic attraction between shared pair of electrons and nuclei of bonded atoms

Question 48

why is benzoic acid less reactive than benzene ?

Answer 48

-COOH is an electron withdrawing group so decreases electron density

Question 49

state 3 differences between Benzene and Kekule

Answer 49

- hydrogenation of bonds less exothermic than expected - all bond lengths the same - requires high temp / halogen carrier (catalyst) for reaction

Question 50

state the difference of electrons between benzene and cyclohexene

Answer 50

cyclohexene - localised electrons | benzene - delocalised electrons (can't polarise molecules)

Question 51

what is the HNMR standard ?

Answer 51

TMS

Question 52

why is benzene hydrogenation enthalpy less exo ?

Answer 52

benzene is more stable

Question 53

why are catalysts good ? (list)

Answer 53

- can use reactions w/ less waste - less energy needed as no high temp - less fossil fuels used up

Question 54

how to get nitro group on phenol, directed to carbon 2 ?

Answer 54

low temp (lower than 50)

Question 55

state the reason for benzenes stability

Answer 55

- delocalised rings above and below plane spread out negative charge - reluctant to undergo addition

Question 56

state conditions for alkene --> alcohol

Answer 56

steam, solid H3PO4 acid catalyst

Question 57

describe how to purify sample of X w/ separation

Answer 57

- add sodium carbonate to remove acid catalyst - transfer to separating funnel and remove bottom layer - add drying agent (mag sulfate) - re distill at B.P. (or filter)