Group 7 Flashcards
Explain the Halide Boiling point trend
Increases as you go down the group
VDW forces increase due to the increasing size and relative mass
Explain the Halide electronegativity trend
Decreases as you go down the group
The atoms get larger and the distance between the positive nucleus and the bonding electrons increases
More shielding
So the ability for the atom to attract the electron density towards itself decreases
Explain the Halide Reactivity trend
Reactivity decreases as you go down the group
For a reaction to occur an electron must be be gained
As atomic radius increases from shielding of extra electron shells
atoms with a larger radius attract electrons worse then atoms with a smaller radius, due to less attractive forces between the nucleus and the bonding electrons
hence its ability to attract an electron decreases
Explain the Halogen Oxidising Power trend
Decreases as you go down the group
Oxidising Power is the ability to oxidise another species
This requires the acceptance of the electron that is lost from the oxidised molecule
As atomic radius increases, atoms with a larger radius attract electrons worse then atoms with a smaller radius, due to less attractive forces between the nucleus and the bonding electrons
More Shielding is Present
So the ability to gain an electron decreases
Explain the Halogen Reducing Power Trend
Increases as you go down the group
Reducing Power is the ability to reduce another species
This requires emitting the electron that is gained by the reduced molecule
As atomic radius increases, atoms with a larger radius attract electrons worse then atoms with a smaller radius due to less attractive forces between the nucleus and bonding electrons
More Shielding is present
So the ability to loose an electron increases.
A Halogen will displace a halide from solution if ________________________
The halide in the solution is less reactive/ lower in the periodic table
Write out the equation for water sterilisation
What reaction type is it and why?
Which of the products is used the kill bacteria
Disproportionation Reaction-> Chlorine is simultaneously reduced and oxidised
ClO- ions are used to kill bacteria
Write out the Equation out for the formation of Bleach
What Reaction type is it and why?
What is the Formula for Bleach?
Disproportionation Reaction-> Chlorine is simultaneously reduced and oxidised
NaClO(aq)
Why does the chlorine in Water Sterilisation need to be topped up often? (use an equation)
Sunlight can decompose the chlorine in the water, without the useful ClO- as a product
What are the uses of bleach?
-Water Treatment
-Bleaching Fabrics and Paper
-Cleaning Agents
What are some advantages to Drinking Chlorinated Water?
-Destroys Microorganisms
-Long Lasting Defence (Reduces Bacteria Build up futher down the Supply)
-Reduces Growth of Algae which can make water foul
What are Some Disadvantages to Drinking Chlorinated Water?
-Chlorine gas is toxic and irritates the respiratory system
-Liquid Chlorine can cause chemical burns
-Chlorine can react with organic compounds to create chloroalkanes within the water supply which have been linked to cause cancerous cells
Write out the Equations for the reaction between Sulphuric Acid and a Halide ion, so that the sulphur containing product has Sulphur at oxidisation state of 6
How would you distinguish this reaction?
What Halides can React is such way?
State the role of the Sulphuric acid
H2SO4 + NaX -> NaHSO4 + HX
HX is a Steamy Fume
Cl Br I
Proton Donor
Write out the Equations for the reaction between Sulphuric Acid and a Halide ion, so that the sulphur containing product has Sulphur at oxidisation state of 4
How would you distinguish this reaction?
What Halides can react in this way
2X- —-> X2 + 2e-
H2SO4 +2H+ + 2e- —> SO2 + 2H2O
O: H2SO4 + 2H+ +2x- —> SO2 + 2H2O + X2
SO2 is a colourless gas
Br2 produces a Brown fume
I2 produces a Purple Fume
Write out the Equations for the reaction between Sulphuric Acid and a Halide ion, so that the sulphur containing product has Sulphur at oxidisation state of 0
How would you distinguish this reaction?
What Halides can react in this way
2X- —-> X2 + 2e- (Multiplied by 3)
H2SO4 +6H+ + 6e- —> S + 4H2O
O: H2SO4 + 6H+ + 6X- —> S + 4H2O + 3X2
S is a yellow solid
I2 produces a Purple Fume
Only iodine has enough reducing power for this
