Elements of Sea Flashcards
Atom economy is…
the measure of the proportion of reacting atoms that become part of the desired product in the balanced chemical equation
Atom economy formula
Mr of desired product/ Total Mr of all products x 100%
Benefits of high atom economy
Little or no waste product
The process is more economically viable
Preserves raw materials
Oxidation is …
loss of electrons or increase in oxidation number
Reduction is …
gain of electrons or decrease in oxidation number
An oxidising agent…
accepts electrons from the species that is being oxidised. It gains electrons and is reduced + reduction in oxidation number
An reducing agent …
donates electrons to the species being reduced. It loses electrons and is oxidised + increases in oxidation number for the reducing agent.
Electrolysis is the…
decomposition of a molten or aqueous ionic compound by passing an electric current through it.
What is the rule at the cathode?
If the metal ions are below hydrogen in the electrochemical series, the metal atoms will be produced at the cathode. If the metal is above hydrogen in the electrochemical series, hydrogen gas will be produced at the cathode.
What is the rule at the anode?
If the solution contains a halide ion. The halogen is formed. If the solution doesn’t contain halide, then oxygen is formed.
The trend of volatility in halogens
Decrease the down group as the boiling point increase
The trend of reactivity in halogens
As you move down the group, reactivity decreases as it becomes harder to attract an electron
Trend of thermal stability in hydrogen halides
Decrease down the group due to increasing bond strength
How does electrolysis work?
Cations are attracted to the cathode and are REDUCED.
Anions are attracted to the anode and are OXIDISED.
Compound is therefore broken up as the two ions do not need each other to be stable
Chlorine is…
a pale green gas
Bromine is ….
a red brown liquid
Iodine is ….
a shiny grey solid with a purple vapour
Trend in reactivity of halogens + why
Down the group it decreases as the number of electron shell increases
This increases the shielding from the nucleus as well as the atomic radius.
Both decrease the attraction between the outer electron and the nucleus. Making it harder for halogens to gain electrons
Trend of volatility of the halogens + why
Decreases down the group because halogens only have instantaneous dipole- induced dipole bonds. The number of electrons in the halogen increases ID- ID bonds become stronger, taking more energy to break
Why are halogens more soluble in cycloheaxan than water?
Halogens are non polar so do not dissolve in polar solvents like water but will dissolve readily in non polar solvent like cyclohexane.
Uses of chlorine
Sterilisation of water
Bleaching for use in the paper or textiles industry
Risks associated with the storage and transport of chlorine?
Chlorine is extremely toxic and can cause damage to lungs and eyes upon exposure
When exposed to water can be carinogenic
Dynamic equilibrium is…
when the rate of the forward and reverse reaction is equal in a closed system and the concentrations remain constant.
What happens to the equilibrium position if the temperature is increased
Endothermic reaction is favoured
