3.3 p block

Question 1

What is the inert pair effect?

Answer 1

the tendency of the s pair of electrons in an atom to stay paired and leads to a lower ox state.

Question 2

What is inert pair stability?

Answer 2

as we descend groups 3+4 the ox state becomes smaller because the inert pair becomes more stable down the group.

Question 3

Discuss group 3 boron nitride

Answer 3

• Boron nitride has similar structures to graphite and diamond and is described as isoelectronic- meaning the same arrangement of electrons.
• hexagonal boron nitride structure- like graphite (electrons are not delocalised in BN) . It is an insulator.
• cubic boron nitride structure- like diamond . It is industrial abrasive.

Question 4

Discuss AlCl3
hint: coordinate bonding

Answer 4

aluminium chloride only has 6 electrons so will form co-ordinate bonds diners if alcl3 form al2cl6 as chorine atoms are electron rich and donate lone pairs to Al valance shell.

Question 5

comparison of graphite and BN

Answer 5

BN two elements but graphite only 1
both isoelectronic
BN has 3 covalent bonds but graphite has 3 and VDW
BN is insulator and graphite is a conductor

Question 6

what is CCL4 reaction with water?

Answer 6

insoluble

Question 7

what is sicl4 reaction with water?

Answer 7

reacts with water steamy fumes

Question 8

what is pbcl2 reaction with water?

Answer 8

dissolves in water

Question 9

reactions of lead with nacl

Answer 9

• white ppt forms
• pb2+ + 2cl- -> pbcl2

Question 10

reactions of lead with NaI

Answer 10

• bright yellow ppt
  pb2+ + 2I- -> pbI2

Question 11

what is chorate 1 ion used for?

Answer 11

bleaching agent

Question 12

what is chlorate 3 ion used for?

Answer 12

weed killer

Question 13

reaction between sulphuric acid and sodium chloride

Answer 13

white misty fumes of hcl are observed

Question 14

reaction between sodium bromide and sulfuric acid

Answer 14

white misty fumes of hbr and orange fumes of bromine

Question 15

reaction between sodium iodide and sulphuric acid

Answer 15

purple fumes of iodine
and rotten egg smell of hydrogen sulfide

Question 16

Equation with NAX and sulfuric acid
x = cl,br,I

Answer 16

NaX(s) + c.h2so4(l) —> NaHSO4(s) + HX(g)

HBr can react further with excess h2so4
h2so4(l) + 2hbr(g) —> so2(g)(colorless gas) + br2(g) ( brown fumes) + 2h20(l)

HI reacts with excess sulfuric acid
just like hbr but forms sulfur(yellow solid) and h2s(colorless gas rotten egg smell) and iodine( purple fumes)

Question 17

group 4 co as a reducing agent
and lead oxide with with hcl

Answer 17

fe203(s) + 3co(g) -> 2fe(s) + 3co2(g)
pbo2(s) + 4hcl(aq) -> pbcl2(s) +cl2(g) + 2h20(l)

Question 18

lead (ll) oxide as an acid and base

Answer 18

Pb0(s) + 2Hn03(aq) -> pb(no3)2(aq) + h20(l)

pb0(s) + 2naoh(aq) + h20(l) -> Na2Pb(OH)4(aq)