Elements of the Sea Flashcards
What is a displacement reaction?
A reaction where a more reactive halogen replaces a less reactive ionically bonded halogen
What is a redox reaction?
A reaction where an element looses electrons and another gains electrons.
Reduction is gain of electrons
Oxidation is loss of electrons
What is a half equation?
A reaction which only shows where electrons are being gained and lost. The spectator ions are not included.
What is a spectator ion?
An ion that remains unchanged before and after a reaction. It isnt directly involved.
What is an ionic equations?
It an equations that has charge symbols and does not include spectator ions.
How do group 7 elements bond?
They bond either ionically with group 1 or
covalently with another group 7 element or hydrogen. This is called a diatomic molecule
What are group 7 trends?
- down the group, boiling / melting points increase
- down the group, they change from liquids to gasses
- They are more volatile up the group
Which halogen is the strongest oxidising agent? and why?
Flourine is the strongest because it is most voltile and reactive.
This is because it wants an electron for its outer shell which is closer to the nucleus which means there is less electron shielding and so there is a greater attraction.
What is a reducing agent?
An atom that causes something to be reduced. It gives away its electrons.
What is an oxidising agent?
An atom that causes another atom to be oxidised. it takes electrons from that other atom.
What happened to the oxidation state when it is:
a) Oxidised?
b) Reduced?
a) the oxidation state increases
b) the oxidation state decreases
What is the usual oxidation state of Cl- ?
-1 because it has been given an electron
Talk about oxidation states and metals?
The oxidation state of a metal can change so to signify it, roman numerals are placed after its name. e.g. Fe(III) or Fe(II)
What is the usual oxidation state of oxygen?
-2
What is the usual oxidation state of hydrogen?
+1
What happens at the anode during electrolysis?
Oxidation happens at the anode because electrons are taken
What happens at the cathode during electrolysis?
Reduction because the cathode gives electrons
What is dynamic equilibrium?
This is when two reactions occur at the same time. The rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of products and reactants remains constant
What is a condition required for something to be in equilibrium?
It must be a closed system (so no products can be added or taken out)
What is the equilibrium constant?
A measure of the position of equilibrium and is based off the values of the analytical concentrations.
What does Kc > 1 mean?
More products are made than reactants
What does Kc < 1 mean?
Less products than reactants are made
What is the equilibrium constant dependent on?
Temperature and pressure
What are the benefits to using chlorine?
Cleans water
Stops illness
Saves lives
What are the risks of chlorine?
toxic
reacts with water
How is chlorine transported?
In specially designed containers with pressure release valves and a hazard warning plate for emergency cervices
What is a test used to indicate the presence of chlorine?
Ammonia soaked cloth produces ammonium chloride which is a white smoke and indicates a chlorine present
What is atom economy?
A measure of how efficient a reaction is as a ration of products to reactants
What is the equation for atom economy?
( RFM Usefull Products / RFM all reactants ) x 100
How does sodium floride/chloride react with sulfuric acid?
It reacts to make a hydrogen halide and sodium hydrogen sulfate.
NaCl + H2SO4 ==> NaHSO4 + HCl
How does sodium bromide react with sulfuric acid?
It first reacts to make hydrogen bromide but it is a strong enough oxidising agent to react with the sulfuric acid again and make sulfur dioxide, bromine and water.
NaBr + H2SO4 ==> NaHSO4 + HBr
2H+ + 2Br- + H2SO4 ==> SO2 + Br2 + 2H2O
How does sodium iodide react with sulfuric acid?
It first reacts to make hydrogen iodide but it is a strong enough oxidising agent to react with the sulfuric acid again and make Hydrogen sulfide , iodine and water.
NaI + H2SO4 ==> NaHSO4 + HI
8H+ + 8I- + H2SO4 ==> H2S + 4I2 + 4H2O
How does HCl react with ammonia?
It make ammonium chloride
NH3 + HCl ==> NH4Cl
