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Flashcards in Halogens Deck (19)
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1
Q

Explain the trend in boiling points of the halogens

A
  1. more electrons down group so stronger van der waals forces between molecules. 2. also size of atom gets larger so molecule size increases so stronger van der waals forces between molecules
2
Q

What is the physical state of At2 at room temperature and explain why

A

solid; At2 is the larges group 7 molecule so has the strongest vdw forces between molecules

3
Q

Which halogen is the best at accepting electrons/best oxidising agent? and explain

A

F. Atoms are the smallest in group 7 with the least shielding so most able to capture external electrons

4
Q

What is he general rule for a halogen displacement?

A

A more reactive halogen can displace a less reactive halogen from a solution

5
Q

What is the colour change when KBr reacts with Cl2? explain your answer

A

from colourless to orange. chorine displaces bromide ions because it is more reactive. Bromine solution is orange

6
Q

What you would observe when KI reacts with Cl2? explain your answer

A

black ppt formed. chlorine displaces iodide ions because it is more reactive. Iodine ppt is black

7
Q

What you would observe when KI reacts with Br2? explain your answer

A

black ppt formed. Bromine displaces iodide ions because Br2 more reactive. I2 is a black ppt

8
Q

Explain why would you add nitric acid (HNO3) to a solution before testing for halides

A

HNO3 gets rid of CO32- which would form the same colour ppt as some halides

9
Q

What is the colour change when you add silver nitrate (AgNO3) to a solution containing Cl- ions?

A

colourless to white

10
Q

What is the colour change when you add silver nitrate (AgNO3) to a solution containing Br- ions?

A

colourless to cream

11
Q

What is the colour change when you add silver nitrate (AgNO3) to a solution containing I- ions?

A

colourless to yellow

12
Q

What is the ionic equation for silver nitrate with chloride ions?

A

Ag+ + Cl- ———> AgCl

13
Q

Explain the trend in oxidising power of the halogens

A
  1. decreases down the group.
  2. atoms get larger so more electrons so more shielding
  3. so ability to attract external electrons decreases
14
Q

Which reactioin with the halides is not a redox equation? hence deduce the type of reaction it is. and what the observation is

A

NaX with H2SO4 forming HX

e.g.

NaCl + H2SO4 ——> NaHSO4 + HCl

therefore neutralisation (acid-base)

in all cases you would see steamy white fumes

15
Q

For the reduction of H2SO4 reacting with HI what are all the main product we are looking for and write the half equations

A

SO2 & S & H2S

2H+ + 2e- + H2SO4 —–> SO2 + 2H2O

6H+ + 6e- + H2SO4 <span>—–</span><span>> <span>S + 4H</span></span>2O

8H+ + 8e- + H2SO4 —–> H2S + 4H2O

16
Q

For the reduction of H2SO4 reacting with HBr (that HI can also do) what is the main product we are looking for and write the half equation

A

SO2

2H+ + 2e- + H2SO4 —–> SO2 + 2H2O

17
Q

What happens when universal indicator paper is added to a solution of chlorine?

A
  1. UI turns red because both HCl and HClO are acids
  2. UI bleeches because the ClO- ion is a bleach
18
Q

What is chlorine used for?

A
  1. water treament
  2. used to make bleach
19
Q
A