halogens

Question 1

bromine

Answer 1

Br2

brown orange liquid

Question 2

iodine

Answer 2

I2

grey solid

Question 3

fluorine

Answer 3

F2

pale yellow gas

Question 4

chlorine

Answer 4

Cl2

pale green gas

Question 5

group 7 halogen

Answer 5

will displace a halide from solution if the halide is lower in the periodic table

Question 6

disproportion- ation reaction

Answer 6

when something is being simultaneously reduced and oxidised

Question 7

potassium iodide + iodine solution

Answer 7

no reaction

equally as reactive so nothing can be displaced

Question 8

potassium bromide + iodine solution

Answer 8

no reaction

KBr is less reactive than iodine

Question 9

advantages of adding chlorine to drinking water

Answer 9

destroys microorganisms that cause diseases

long lasting so reduces bacteria build up

reduces growth of algae that discolours water and gives a bad taste/smelll

Question 10

disadvantages of adding chlorine to drinking water

Answer 10

chlorine gas is toxic and irritates respiratory system

liquid chlorine can cause chemical burns to skin

Cl2 can react with organic compounds to make chloroalkanes which causes cancer

Question 11

reducing power of halide ions

Answer 11

reducing agents (loses an e-)

ionic radius increases

distance between nucleus and outer e- become larger (more shielding)

outer e- is more readily

Question 12

potassium bromide + chlorine water

Answer 12

forms an orange solution

Cl2+2Br- —2Cl-+Br2

Question 13

potassium chloride + iodine solution

Answer 13

no reaction

iodine is less reactive than chlorine so can’t displace

Question 14

potassium iodide + bromine water

Answer 14

forms brown solution

Br2+2I- — 2Br- +I2

bromine is more reactive than iodine

Question 15

potassium bromide + bromine water

Answer 15

no reaction because 2 bromines are reacting together

Question 15

potassium chloride + bromine water

Answer 15

no reaction

bromine is less reactive than chlorine so displacement reaction can’t take place

Question 16

potassium iodide + chlorine water

Answer 16

forms brown solution

Cl2+2I- —2Cl- +I2

chlorine reacts with iodine

iodine displaced chlorine ions

Question 17

potassium chloride + chlorine water

Answer 17

no reaction because 2 chlorines are reacting together

Question 18

uses of sodium chlorate

Answer 18

treating water

bleaching paper or fabric

cleaning agents (bleach)

Question 19

equation for bleach

Answer 19

2Na(aq)+Cl2(g) — NaClO(aq) + NaCl(aq) + H2O(l)

Question 20

reactivity trend

Answer 20

decreases

for a reaction to occur an e- has to be gained

smaller radius attracts e- better than larger atoms

Question 21

electronegativity trend

Answer 21

decreases

atoms get bigger

distance between positive nucleus. and bonding e- increases

more shielding

Question 22

boiling point trend

Answer 22

increases

van de waals forces increase

size and relative mass of atoms increases

gas — solid (not liquids)

Question 23

testing for cations (flame test)

Answer 23

1. dip the nichrome wire with concentrated HCl
2. dip into sample
3. place the loop into a blue bunsen burner flame and observe the colour change

dark red - Ca2+
green - Ba2+
red - Sr2+

Question 24

testing for ammonium compounds (litmus paper)

Answer 24

1. add NaOH
2. heat

results - ammonium gas

3. use damp litmus paper and ammonia will dissolve (blue)

Question 25

testing for hydroxides (litmus paper)

Answer 25

1. add NaOH
2. heat

results- turns red litmus paper blue

only shows that it’s an alkali not what specific hydroxide is present

Question 26

testing for carbonates (HCl)

Answer 26

1. HCl reacts with carbonates to form CO2 gas
2. limewater will turn it cloudy

Question 27

testing for sulphates

Answer 27

1. add HCl to remove carbonates
2. add BaCl

results- an insoluble white precipitate

Ba2+ + SO42- — BaSO

Question 28

electronegativity

Answer 28

the ability for an atom to attract e- towards its covalent bond