C3 Flashcards
What’s the formula for alkenes?
CnH2n
What is the formula of alkanes?
CnH2n+2
what is covalent bonding ?
when two non metal atoms share a pair of electrons to form a complete outer shell
what is ionic bonding?
non metal and metal
what is metallic bonding?
metals
what are alkanes?
hydrocarbons that are made of hydrogen and carbon atoms and are saturated (single bonds only)
what are alkenes?
formed when we crack large alkanes (one double bond so unsaturated)
the carbon is a double bond
what are intermolecular forces?
the weak forces between molecules that hold them together
melting and boiling points of simple covalent molecules
the melting and boiling points are low because there are weak intramolecular forces that require low energy to break
conduction of electricity
simple covalent molecules do not conduct electricity as they have no electric charge
first 4 alkanes
Monkeys Eat Peanut Butter
methane, ethane, propane, butane
first 4 alkenes
ethene, propene, butene, pentene
features of short chain hydrocarbons
short chain hydrocarbons contain lower boiling points, higher volatility, low viscosity, and are extremely flammable
volatility
rate of evaporation
viscosity
consistency
features of long chain hydrocarbons
Long chain hydrocarbons have higher boiling point, less volatility, more viscous and less flammable
why do long chain hydrocarbon have higher melting points than shorter hydrocarbon chains?
longer hydrocarbon chains have more intermolecular forces which require more energy to break the forces
how does fractional distillation work?
- heat the mixture so it boils at the bottom to form vapours
- vapour rises at column
- the column is hot at the top and cool at the bottom
- vapours condense at different temperatures, depending on their boiling points
what is cracking?
it is a process that is used to decompose large molecules into smaller, more useful molecules as the lighter fractions are in high demand as they are more useful as fuels
how do you crack?
large chain alkane —> smaller chain alkane and alkenes
heat long chain hydrocarbons to vapourise them —> pass vapours over a hot catalyst or mix with steam —> heat to high temperature for thermal decomposition to occur
how do you work out empirical formula?
- divide masses by relative atomic mass
- divide by smallest number
- get the ratio by rounding
- write it in the formula
what is the order of the reactivity series?
potassium
sulphur
calcium
magnesium
aluminium
carbon
zinc
iron
tin
lead
hydrogen
copper
silver
gold
what are metallic bonds?
the electrostatic attractions between positive metal ions and negative delocalised electrons
what are metals arranged of?
giant metallic lattice of cations
what are delocalised electrons?
electrons that are not bound to an atom and are free to move around within the lattice
movement in the structure
metal ions and delocalised electrons are attracted together by strong electrostatic forces of attraction due to opposite charges
what are the properties of pure metals?
- high melting and boiling
points - soft andmalleable mallaable
what makes metals malleable?
layers of ions can slide eover each other
how do metals conduct heat?
the delocalised electrons transfer thermal energy as they move
how do metals conduct electricity?
they have free electrons that can move throughout the metal, carrying a charge
how does lithium react with water?
- gives off hydrogen
- fizzes
- turns purple
how does sodium react with water?
- silver ball
- floats and fizzes
- explodes and dissolves
how does potassium react in water?
- lilac flame
- bubbles catches fire
how does lithium react with air?
turns from silver to black
how does sodium react with air
turns from silver to grey
how does potassium act with air?
turns white to black
why do group 1 metals get more reactive as you go down the group?
the number of shells increase and the outer electron is away from the nucleus so its easier to lose as the attraction between it and the nucleus is weaker
the reactions of reactive metals with water - equation
metal+water→metal hydroxide+hydrogen
the reactions of reactive metals with acids?
metal and acid–> salt and hydrogen
what metals cant react with dilute acids?
copper, silver, gold and platinum
what metals react with dilute acids?
magnesium, aluminium, zinc, iron and lead (iron and lead react slowly)
the reactions of reactive metals with oxygen
metal +oxygen→metal oxide
what is the reactive series?
a list of metals from mostr reactive to less reactive
reactive series acronym
please send cats monkeys and carbon zebras in the lead hydrogen cage securely guarded please
what is a displacement reaction?
a reaction where a more reactive metal will displace a less reactive metal from a compound
what is an ore?
a rock with enough metal atoms to make it exploitable
reducing metals with carbon
if the ore has a metal LESS reactive than carbon, we can use carbon to reduce the metal
- carbon gets oxidised
why is carbon used in extraction?
it is cheap and abundant
how do you reduce the metal with carbon?
reduction with carbon normally involves heating the metal oxide in the presence of the carbon, which is often used in the form of coal
how does bioleaching work?
Bacteria are mixed in with low-grade ores.
The bacteria convert the metal into a solution rich in metal compounds called leachate solution.
This gets extracted using electrolysis or displacement
how does phytomining work?
Plants growing on contaminated land absorb metal ions as they grow.
These plants are harvested and burned, producing ash that contains high concentrations of metal compounds that get extracted with electrolysis or displacement
what are the disadvantages of bioleaching?
they are take lots of time to produce a large quantity of metal
some toxic chemicals are produced that are harmful to wildlife
what are the disadvantages of phytomining?
it can be very slow but this can be combatted by planting plants that grow relatively quickly
what are the advantages of phytomining?
- it can work with low grade ores that would be wasted
- it can clear up contaminated sites
- it very cheap
- it can be used by developing countries to build up economies
what are the advantages of bioleaching?
- it can work with low grade
ores that would be wasted - it is energy efficient
- it can be used by developing countries to build up economies
what is electrolysis?
using electricity to split iionic compounds
what is electrolyte?
An ionic compound that produces a solution that conducts electricity when it is dissolved in water.
what is the anode?
positive electrode
what is the negative electrode?
cathode
what charge do metal ions have?
positive
where will metals form?
at the cathode which is the negatively charged electrode as they have positively charged ions (cations)
what is formed at the anode if halide ions are present?
the respective halogen forms
what is formed at the anode if halide ions arent present?
oxygen/hydroxide
what is formed at the cathode in aqueous electrolysis?
metal or hydrogen
- the least reactive gets
discharged
where does reduction happen?
at the cathode
- positively charged ions gain electrons
where does oxidation happen?
at the anode
- negatively charged ions lose electrons
where do you get aluminium oxide?
bauxite
what do u mix w aluminium and why?
cryolite to lower the melting point
