Chem Flashcards
Explain why air needs to be replaced with argon gas for the reduction of titanium chloride
Oxygen in the air reacts with titanium
This makes titanium brittle
Give reasons why electrolysis will be more efficient method of extraction than kroll process
Has fewer stages
Uses a lower temperature
Uses less chemicals
Gives a higher yield
Compare similarities and differences between extraction of aluminium and extraction of chlorine by electrolysis (6 marks)
Similarities
-elements are formed at the cathode and anode
-Ions are free to move in both compounds
-Both raw materials are ionic compounds
Differences
-Alumina is an oxide but brine is a chloride
-Electrolysis of alumina requires more energy than brine
-Electrolysis of brine uses a membrane
-No ions are left behind in the electrolysis of alumina
Describe how the water molecules are bonded to the vanadium iron
Dative Covalent bond from water to vanadium ion
Describe how the ultraviolet light causes the reaction to begin
Breaks the bromine bond from the free radical form atom has a single electron
Describe the process of sp2 hybridisation for a carbon atom
There is 1 S orbital and 2 P orbitals involved they mix
Each orbital holds one unpaired electron
The energy level of the S orbital increases
The hybrid orbitals are identical
Describe where each product is formed during the electrolysis of brine
Hydrogen is formed at the cathode
Chlorine is formed at the anode
Sodium hydroxide is left behind in the solution and it remains behind in the cell
Discuss the advantages and disadvantages of the manufacture of ethanol by the hydration of ethene (6 marks)
Advantages
-All reactants used up to form ethanol
-Raw material is easy to obtain
-Higher temperature, so quicker reaction
Disadvantages
-It’s a reversible reaction, so there will not be 100% yield of ethanol
-High temperature so greater cost
-It’s nonrenewable as it uses fossil fuels. This is bad for the environment.
Explain how transition metal often works as catalyst
Speeds up the reaction
Provides an alternative route with a lower activation energy
Transition meals change oxidation state
Explain how the carbon to carbon bond strength in ethane is different to ethene
-Only a single bond in ethane
-So Ethane has the longer chain
Ethane is weaker, so it is easier to break
-More electrons are shared between the two carbon atoms in the ethene
-atoms in the ethene.
Explain how the diaphragm cell is used to produce sodium hydroxide, chlorine and hydrogen (6 marks)
-Brine is sodium chloride
-Contains sodium ions, chloride ions, hydrogen ions and hydroxide ions
Ions are free to move the solution and carry electrical charge
-Negative Chloride ions attracted to the positive anode
-The sodium and hydroxide ions are left in the solution. This forms HCl
-Sodium hydroxide and chlorine react together to form sodium chlorate
-Diaphragm separate sodium hydroxide from chlorine so that they do not react together
Explain the difference in bond length between a carbon-carbon double bond and a carbon-carbon single bond
A double bond is shorter than a single bond
There are more electrons in a double bond
This is a two carbon atoms closer together
Explain the effect of using a catalyst in the haber process
Speeds up the reaction and provides a surface area for the particles to react upon
Bonds within the reactant particles are weakened
More collisions
Electrolysis of brine can be carried out in a membrane cell
Explain the function of the membrane cell
Membrane keeps chlorine gas separate from the sodium hydroxide
Chlorine will not be able to react with the hydrogen
The membrane is not allow negative ions to pass through
Sodium hydroxide solution higher purity
Explain the three stages of the three radical mechanism involved in the formation of chloromethane (6)
It is a chain reaction
Initiation is the first stage the UV light provide energy for the reaction
Forms Free radicals
Propagation is the next stage
Chlorine radical removes the hydrogen from the methane, and this forms a methyl radical
The chlorine free radical removes the hydrogen from another methane
Termination is the end of the reaction
To me, feel of radical reacts with the chlorine radical to form chloromethane
Methyl radical react to form Ethane
Explain why Alumina must be dissolved before electrolysis can take place
To allow ions to move so the ions can carry the electrical current during the electrolysis
Give two reasons why electrolysis of alumina is expensive
Large amount of energy is required to maintain high temperature to dissolve the alumina
Large amount of electricity is required for electrolysis
Why benzene cannot be an alkene
Benzene has the same number of hydrogen as carbons
Benzene does not have 12 hydrogen atoms
Explain why manganese oxide can act as a catalyst
It has incomplete d subshell
It can accept or lose electrons
And this means it can be oxidised or reduced to back again to its original form
It lowers activation energy
The extraction of titanium from its ore uses two redox reactions
Carbon is oxidised
Chlorine is reduced
Titanium and oxygen is not reduced or oxidised in this reaction so there is no change in oxidation number
Titanium is reduced
Magnesium is oxidised
Magnesium displace, titanium
Chlorine is not oxidised or reduced in this reaction
