3.2.3 group 7 metals

Question 1

what observation can be made when Br2 is formed?

Answer 1

orange solution is made

Question 2

why does chlorine have a lower boiling point than bromine?

Answer 2

• chlorine has fewer electrons
• less vdw intermolecular forces between molecules

Question 3

why do bromide ions react differently from chloride ions?

Answer 3

• they are bigger than Cl- ions
• Br- ions more easily oxidised

Question 4

what must you make sure you do after you filter a precipitate?

Answer 4

• wash to remove soluble compounds
• dry to remove water

Question 5

how do forces arise between molecules of chlorine?

Answer 5

• random movements in electrons
• temporary attraction between slightly + and slightly -
• temporary dipole is formed

Question 6

what’s the equation of chlorine reacting with water?

Answer 6

2Cl2 + 2H2O —> 4HCl + O2

Question 7

why is nitric acid added to solution to test for chloride and iodide ions?

Answer 7

removes carbonate ions that may give other ppts with AgNO3

Question 8

why is water treated with chlorine and why’s it added even tho it’s toxic?

Answer 8

• kills bacteria
• heath benefits outweigh risks

Question 9

why may excess AgNO3 be used to test for halide ions?

Answer 9

to ensure all halide ions are removed from the solution

Question 10

what is observed when AgNO3 is added to NaF?

Answer 10

NVC

Question 11

how would you differentiate sodium carbonate, sodium fluoride and sodium chloride?

Answer 11

• add nitric acid to all 3
• add water to all 3!to make it a solution
• add AgNO3
• Na2CO3 fizzes with acid
• NaCl gives white ppt with AgNO3
• NaF shows NVC

Question 12

what is the trend in electronegativity down group 7?

Answer 12

• decreases
• atomic radius increases
• weaker attraction by nucleus on bond pair in the covalent bond

Question 13

how is bleach produced?

Answer 13

when chlorine is mixed with cold, aqueous sodium hydroxide to produce NaClO

Question 14

NaBr + H2SO4 –> ?

Answer 14

Br2 + SO2 + 2H2O

Question 15

why is AgNO3 acidified before testing?

Answer 15

• removes ions that would interfere with test
• prevents formation of other silver precipitates

Question 16

NaF + H2SO4 —>

Answer 16

NaHSO4 + HF

Question 17

NaCl + H2SO4 —>

Answer 17

NaHSO4 + HCl

Question 18

are silver halides insoluble in water?

Answer 18

yes, apart from AgF

Question 19

what’s the equation for bleach production?

Answer 19

2NaOH + Cl2 —> NaClO + NaCl + H2O

Question 20

what’s the equation of sodium bromide reacting with sulfuric acid?

Answer 20

2NaBr + 2H2SO4 —> Na2SO4 + Br2 + SO2 + 2H2O

Question 21

what’s the role of H2SO4 in NaCl + H2SO4 ?

Answer 21

base

Question 22

what’s the equation for when AgBr reacts with dilute ammonia?

Answer 22

AgBr + 2NH3 —> (Ag(NH3)2)+ + Br-