chem

Question 1

what is the standard hydrogen electrode composed of

Answer 1

acidic solution (for H+ ions)
solid platinum
Hydrogen fed to Pt

Question 2

what is the standard hydrogen electrode used for and wht

Answer 2

reference/measurement
potential is 0

Question 3

what is the half equation for the she

Answer 3

2H+ + 2e- -> H2

Question 4

why is platinum used for she

Answer 4

inert (little corrosion)
catalyst

Question 5

equation for SO2 + H2O

Answer 5

SO2 + H2O -> H2SO3

Question 6

equation for SO3 + H2O

Answer 6

SO3 + H2O -> H2SO4

Question 7

why is 2nd ionisation typically greater than 1st

Answer 7

after 1st, is positive ion so electrostatic attraction

Question 8

Explain why [Al(H2O)6]3+ is acidic

Answer 8

high charge density, polarising
weakens OH bond
H donated to H2O

Question 9

why is electrospray used

Answer 9

so the larger molecule doesnt break up

Question 10

what happens at anode of fuel cell

Answer 10

anode - cations - loses electrons
2H2 + 4OH- -> 4H2O + 4e-

Question 11

what happens at the cathode of a fuel cell

Answer 11

cathode - anions - gains electrons
O2 + 2H20 + 4e- –> 4OH-

Question 12

why cant an indicator be used for a titration between a weak acid and weak base

Answer 12

the pH change is too gradual, the color change would be difficult to observe

Question 13

heterogenous

Answer 13

different state

Question 14

homogenous

Answer 14

same state

Question 15

what does a similar ionic model enthalpy and born-haber model enthalpy show

Answer 15

that the chemical is perfectly ionic and has little covalent character

Question 16

what happens when [Al(H2O)6] 3+is added to NH3

Answer 16

the Al complex is neutralised Al(H2O)3(OH)3 and dissociates 3 H+ to NH3 to form NH4+

This occurs with all metals (exception copper with excess of NH3)

Question 17

left of Al the metal oxides are basic or acidic

Answer 17

basic

Question 18

developing agent chromatography

Answer 18

ninhydrin

Question 19

reagent and condition for hydrolysis of proteins

Answer 19

hcl + heat

Question 20

when distinguishing between period 3 oxides use what?

Answer 20

universal indicator :)

Question 21

silicon dioxide forms simple/giant

Answer 21

giant,
trioxide forms simple

Question 22

describe electrospray

Answer 22

dissolved in volatile solvent
injected through needle + high voltage
gains a proton
P + H+ -> PH+

Question 23

what is periodicity

Answer 23

describes REPEATING trend

Question 24

example of linear complex

Answer 24

[Ag(NH3)2]+

Question 25

factors affecting substitution transition metals

Answer 25

water is weak
multidentate strong
increase in entropy forms stronger complex

Question 26

reagents for reducing vanadium

Answer 26

zn + acid

Question 27

[Cu(H2O)6] 2+ with excess of ammonia

Answer 27

normal: [Cu(H2O)6]2+ 2NH3 -> [Cu(H2O)4(OH)2]
excess: [Cu(H2O)6] + 4NH3 -> [Cu(NH3)4(H2O)2] 2+ + 4H2O
(deep blue)
(this excess reaction only occurs with copper)

Question 28

CuCO3 color

Answer 28

blue-green

Question 29

color of [CuCL4]

Answer 29

yellow-green solution

Question 30

enthalpy change

Answer 30

change in heat energy at constant pressure