The Halogens Flashcards
what is the colour and state of fluorine in its physical state ?
pale yellow GAS
what is the colour and state of chlorine in its physical state ?
green GAS
what is the colour and state of bromine in its physical state ?
red-brown liquid
what is the colour and state of iodine in its physical state ?
black solid
describe the trend in boiling points down the halogens (4)
- boiling point increases down group
- number of electrons increases
- greater IDDI between mlcls
- more energy needed to overcome IDDI
describe the trend in reactivity down group 7 (6)
- reactivity decreases down group
- more electron shells
- greater electron shielding
- greater atomic radius
- weaker nuclear attraction between nucleus and outermost electron
- attracts an electron to form an anion less readily
which halogen is the most reactive ?
fluorine
which halogen has the greatest boiling point out of fluorine, chlorine, bromine or iodine
iodine
which halogen acts as the best oxidising agent ?
fluorine
write an ionic equation for the displacmentreaction which occurs when bromine reacts with sodium iodide
Br2 (aq) + 2I- (aq) = 2Br- (aq) + I2 (aq)
describe what is found in the organic and aqueous layer which results after a displacment reaction (2)
- non polar halogen wil disolve in non polar organic layer
- polar halide will disolve in polar aqueous layer
give an example of an aqueous and organic solvents that can be used for the displacement reaction between halides and halogens
organic: hexane
aqueous: water
what is the colour of Cl2 when it is dissolved in water - Cl2 (aq)
pale green
what is the colour of Br2 when it is dissolved in water- Br2 (aq)
orange
what is the colour of I2 when it is dissolved in water - I2(aq)
brown
what is the colour of Cl2 when it dissolves in the organic solvent: hexane
pale yellow - green
what is the colour of Br2 when it dissolves in the organic solvent: hexane
yellow-orange
what is the colour of I2 when it dissolves in the organic solvent: hexane
purple
describe the method used for a diaplacement reaction (3)
- use seperating funnel
- shake hexane with dilute aqueous halide solution
- aqueous and organic layer form - organic on top
describe a p[ractical use of chlorine (1)
sterilise water by killing bacteria
describe the process of chlorination of water include any relevent equations (4)
**step 1: **
Cl2 (aq) + H2O (l) = HCL (aq) + HClO (aq)
chloric acid formed - kills bacteria
**step 2: **
HClO (aq) = H+ (aq) + ClO- (aq)
chlorate(I) formed - sterilising agent
what would the observations be if universal indicator was added to the firat step of water chlorination ? (2)
- first it would trun red - due to acidic product (HCl)
- then turns colourless - HClO bleaches colcour
state some advantages of using chlorine to sterilise water and kill bacteria (3)
- highly effective at killing bacteria
- simple maintenance
- not expensive
state some disadvantages of using chlorine to sterilise water and kill bacteria (3)
- chlorine is toxic
- forms halogenated hydrocarbons
- forms carcinogenic cmpnds
