Redox Chapter 7 - 10 and 22 Flashcards
In terms of oxygen
What is oxidation and reduction
Oxidation is gain of oxygen
Reduction is loss of oxygen
In terms of oxygen
What is the oxidising and reducing agent
Oxidising agent is oxygen donor
Reducing agent is oxygen acceptor
In terms of hydrogen
What is oxidation and reduction
Oxidation is loss of hydrogen
reduction is gain of hydrogen
In terms of hydrogen
What is the oxidising and reducing agent
Oxidising agent is hydrogen acceptor
Reducing agent is hydrogen donor
What is oxidation and reduction in terms of electrons
Oxidation is loss
Reduction is gain
What is the oxidising and reducing agent in terms of electrons
Oxidising agent is electron acceptor
Reducing agent is electron donor
What is oxidation state
It is another way to work out what is going on in a redox reaction
The oxidation state of any element shows the number of electrons over which it has lost or gained
What does the sign show for oxidation state
Positive - loss of electrons
negative - gain of electrons
What rules are there for oxidation numbers
All elements are 0
The number of ions is the charge of the ion
In compounds the sum of numbers is zero
Group 1 are +1
Group 2 are +2
Aluminium is +3
Fluorine is -1
What elements are special for oxidation numbers
Oxygen is -2 - except in peroxides -1 and in OF2 when its +2
Hydrogen is +1 - except in metal hydrides -1
Chlorine is -1 - except in compounds with O or F where its positive
What are the rules for half equations
Only one element changes oxidation state
Balance oxygen atoms with water
Balance hydrogen atoms with H+
Balance the charges with electrons
Rules for adding half equations
One must be oxidation and the other reduction
The number of electrons must be the same
The equation must balance for electrons and atoms
What structure are sodium, magnesium and aluminium
Giant Metallic
What structure is silicon
Macromolecular
What structure is P, S and Cl
Simple molecular
What structure is Argon
Simple atomic
What is the trend in melting point for period 3 and why
Increases from Na to Si as bond strength increases
Decreases from P to Ar as Van der Waal forces decreases as molecular size decreases
What is the trend with BP across period 3
Increases from Na to Al as metallic bond gets stronger
Decreases from Si to Ar VDW get weaker as size decreases
Trend of atomic radius across period 3
Decreases across period as nuclear charge increases
Trend in first ionisation energy across period 3
Increases across period as nuclear charge increases and shielding remains constant
Why is there a decrease in 1st IE from Mg to Al
Al’s outer electron is in a less shielded 3p orbital
Why is there a decrease in 1st IE energy from P to S
S has a pair of electrons in orbital causing repulsion
How does Sodium react with water
Equation
Fizzing
Turns alkaline
Gives off heat
2Na + 2H2O –> 2NaOH + H2
How does magnesium react with water
Reacts slowly
Forms weak alkali
Mg + 2H2O –> MgO + H2 Steam
Mg + 2H20 –> Mg(OH)2 + H2
How does Sodium react with oxygen
Vigorous reaction
Burns with yellow flame
4Na + O2 –> 2Na2O
White solid
How does magnesium react with oxygen
Vigorous reaction
Burns with white flame
2Mg + O2 –> 2MgO
How does aluminium react with oxygen
Vigorous reaction
4Al + 3O2 –> 2Al2O3
How does silicon react with oxygen
Low reaction
Requires heat
Si + O2 –> SiO2
How does phosphorous react with oxygen
Red phosphorous must be heated for reaction
White phosphorous reacts spontaneously
P4 + 5O2 –> P4O10
White flame
How does sulphur react with oxygen
Sulphur melts easily
Blue flame
Pungent choking gas
S + O2 –> SO2
What are the melting points of Non-Metal oxides
Silicon oxide has a giant covalent structure so high MP
Phosphorous oxide and sulfur oxide are simple covalent molecules so low MP’s
What are the properties of metal oxides
High MP and BP
Mp increases across period as the charge is higher and so the forces are higher
How does sodium oxide react with water
Bubbles
pH 13
Dissolves exothermically
Na2O + H2O –> 2NaOH
How does magnesium oxide react with water
pH 9
Sparingly soluble
MgO + H2O –> Mg(OH)2
How does aluminium oxide react with water
Insoluble
Bonding is too strong
How does Silicon oxide react with water
Insoluble
How does phosphorous oxide react with water
Violent reaction
pH 1
P4O10 + 6H2O –> 4H3PO4
How does sulfur dioxide react with water
pH 3
Soluble
SO2 + H2O –> H2SO3
The product is a weak acid
How does Sodium and magnesium oxide react with acids and bases
They are both basic oxides and will react with acids
Na2O + H2SO4 –> Na2SO4 + H2O
MgO + H2SO4 –> MgSO4 + H2O
How does aluminium oxide react with acids and bases
It is a amphoteric oxide so can be acidic and alkaline so reacts with both acids and bases
Al2O3 + 6HCl –> 2AlCl3 + 3H20
Al2O3 + 2NaOH + 3H2O –> 2NaAl(OH)4
How does Silicon dioxide react with bases
It acts as a weak acid with strong bases
SiO2 + 2NaOH –> 2Na2SiO3 + H2O
How does phosphorous oxide react with bases
It reacts with bases
It becomes phosphoric acid when in water
H3PO4 + 3NaOH –> Na3PO4 + 3H2O
Does sulphur dioxide react with bases
It reacts
SO2 + NaOH –> NaHSO4
NaHSO3 + NaOH –> Na2SO3 + H2O
Describe sodium oxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
White solid
Ionic
Dissolves exothermically
13
Base
Describe Magnesium oxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
White solid
Ionic
Sparingly soluble
9
Base
Describe aluminium oxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
White solid
Ionic (covalent character)
Insoluble
7
Amphoteric
Describe Silicon dioxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
White solid
Giant covalent
Insoluble
7
Acidic
Describe Phosphorous oxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
White solid
Simple molecular
Violent reaction
1
Acidic
Describe Sulfur dioxide
Appearance
Structure
Solubility with water
pH in water
Acid/base/amphoteric
Gas
Simple molecular
Soluble
3
Acidic
What is group 2 called and why
The alkaline earth metals
Because their oxides and hydroxides are alkaline
What is the trend in atomic radius in group 2
Increases down the group
More electron shells
Bigger atoms
What is the trend in melting point in group 2
Decreases down the group
Weaker metallic bonding
As metal ions get bigger the sea of delocalised e- are further from nucleus
Mg doesn’t follow trend as it has a different lattice structure
What is the trend in 1st IE in group 2
Decreases down the group
e- are further from nucleus
More shielding
Weaker attraction from nucleus to electron
How does group 2 metals react with water
Redox reaction
M + 2H20 –> M(OH)2 + H2
React more violently as you go down the group
What is the solubility of group 2 hydroxides
They are increasingly soluble down the group
Mg - insoluble
Ca - Slightly soluble
Sr - Soluble
Ba - Soluble
What is the solubility of group 2 sulphates
Sulphate solubility decreases down the group
Mg Soluble
Ca Slightly soluble
Sr and Ba insoluble
What are the uses of Magnesium hydroxide
Treat constipation
Extract titanium
Uses of Calcium hydroxide
Root canal fillings
Sewage treatment
Uses of calcium oxide
used to manufacture cement
Ingredient for caustic soda
Uses of calcium carbonate
Used to relive heartburn
Uses of barium sulphate
Used in CAT scans
Test for sulphate ions
Solution is acidified
Barium chloride is added
If sulphate ions are present, a white precipitate is formed
Ba2+ + SO4 2- –> BaSO4
Why is the fluorine fluorine bond weak
This is due to the small size of the atoms which leads to a repulsion between electrons
What is the trend in atomic radius in group 7
Increases down the group
More shells
Bigger atoms
What is the trend in electronegativity in group 7
decreases down the group
bigger atoms
more shielding
What is the trend in boiling points down group 7
increases
Stronger van der waal forces
Trend in 1st IE down group 7
Decreasing
Atoms get bigger
More shielding
What is the trend in oxidising ability down group 7
Decreasing
They gain electrons
Harder to gain electrons as atoms are larger and more shielding
How strong of reducing agents are fluorine and chlorides
They aren’t very strong so a displacement reaction occurs instead
How strong of a reducing agent is bromide
Bromide ion can reduce sulphuric acid
First is a displacement type reaction
NaBr + H2SO4 –> NaHSO4 + HBr
The HBr is oxidised in a redox reaction
2Br- +H2SO4 + 2H+ –> SO2 + 2H2O + Br2
How strong a reducing agent is iodine
It is powerful enough to reduce sulphuric acid to sulphur dioxide then sulphur and then hydrogen sulphide
NaI + H2SO4 –> NaHSO4 + HI
2I- + H2SO4 + 2H+ –> I2 + SO2 + 2H2O
6I- + H2SO4 + 6H+ –> 3I2 + S + 4H2O
8I- + H2SO4 + 8H+ –> 4I2 + H2S + 4H2O
What are the products from sodium fluoride with sulphuric acid
HF
Displacement reaction
What are the products of NaCl reacting with H2SO4
HCl
Displacement reaction
What are the products of NaBr reacting with H2SO4
HBr - displacement
SO2 - H2SO4 reduction
Br2 - Br- oxidation
What are the products from NaI reacting with H2SO4
HI - displacement
SO2 and S and H2S - H2SO4 reduction
I2 - I- oxidation
What are chlorine’s uses
Water treatment as its soluble in water
Cl2 + H2O –> HCl + HClO
This is a disporoportionation
What is a disporoportionation
A reaction in which the same species is both oxidised and reduced
What reaction does chlorine have with water in sunlight
2Cl2 + 2H2O –> 4HCl + O2
What else can be used to chlorinate pools
Sodium chlorate
Cl2 + 2NaOH –> NaCl + NaClO + H2O
NaClO + H2O –> Na+ + OH- + HCLO
Why are pools kept slightly acidic
in an alkaline solution the equilibrium would shift to the left
What is the test for group 2 ions
Add sodium hydroxide
Add dilute sulphuric acid
What are the results for the group 2 ions when sodium hydroxide is added
Magnesium - White precipitate
Calcium - White precipitate
Strontium - colourless solution
Barium - Colourless solution
What are the results for the group 2 ions when sulphuric acid is added
Magnesium - Colourless solution
Calcium - Colourless solution
Strontium - slight white precipitate
Barium - White precipitate
test for sulphate ions
HCl and barium chloride
Solution turns white, white precipitate formed
What is the tests for chloride.bromide and iodide ions
Silver Nitrate
Chloride - White precipitate
Ag+ + Cl- –> AgCl
Bromide - Cream Insoluble
Ag+ + Cl- –> AgBr
Iodide - Yellow
Ag+ + I- –> AgI
How does dilute ammonia react with silver chloride, bromide and Iodide
Dilute NH3
Chlorine - Colourless solution
AgCl + 2NH3 –> [Ag(NH3)2]+ + Cl-
Bromine - Precipitate
Iodine - Precipitate
What are the tests for halide ions when in solid form
Add concentrated sulphuric acid
Chloride - Acid formed and misty gas formed
Bromide - Misty gas, orange vapour
Iodide - Turns acidic, Black solid bad egg smell, gas
Test for carbonate ions
Add HCl
Lime water turns cloudy, Fizzy and colourless solution
Test for hydroxide ions
Universal indicator turns purple
Test for ammonia ions
Red litmus paper turns dark blue
Test for ammonium ions
NaOH
Gas formed turns Red litmus paper blue
How does concentrated ammonia react with silver chloride, bromide and Iodide
Chlorine - Colourless solution
AgCl + 2NH3 –> [Ag(NH3)2]+ + Cl-
Bromine - Colourless solution
AgBr + 2NH3 –> [Ag(NH3)2]+ + Br-
Iodine - Precipitate
What does a brown precipitate mean when reacted with NaOH
Iron 3
What is the observation of HCl
Steamy fumes
What is the observation of HBr
Steamy Fumes
What is the observation of Br2
Brown fumes
What is the observation of SO2
Colourless Gas
What is the observation of HI
Steamy Fumes
What is the observation of I2
Purple Fumes
What is the observation of SO2
Colourless gas
What is the observation of S
Yellow Solid
What is the observation H2S
Gas
Bad egg smell
What is the reaction of chlorine with cold dilute sodium hydroxide
Cl2 + 2NaOH-> NaCl + NaClO + H2O
Sodium chlorate is an active ingredient in household bleach
How does aluminium react with sodium hydroxide
White precipitate which dissolves in excess NaOH
Who has a greater first ionisation energy, magnesium or Aluminium
Magnesium
Aluminium has covalent character
What is the definition of periodicity
Repeating pattern/trends of physical or chemical properties/reactions
What is a Lewis acid
a species that accepts an electron pair
What is a Lewis base
a species that donates an electron pair
What is a Bronsted Lowry base
It is any species that is capable of accepting a proton
What is a Bronsted Lowry Acid
It is any species that is capable of donating a proton
How do you differentiate sulfur dioxide and sulfur trioxide
Universal Indicator
SO2 - orange red
SO3 - Red