Chemistry 2019 Flashcards
What is the kinetic theory of ideal gas
1) Gases are made of particles in constant random motion
2) The particles move very fast and collide with eachother and the walls of their container with perfectly elastic collisions
3) The particles are negligible in size when compared with the space between them
4) There are no attractive or repulsive forces between the particles
5) The average kinetic energy of the molecules is proportional to the temperature of the gas
If the number of gas particles in a container doubles, the gas pressure is _____________
doubled
If the temperature in a fixed volume container is increased, the gas pressure _______________
increases
What are exceptions to the kinetic theory of ideal gas
- At high pressures of gas, the particles are very close together, the volume has to be considered, the intermolecular forces are strong enough to affect the collisions against the container therefore reducing pressure
- at very low temperatures the gas particles no longer have enough energy to overcome the attractive forces between them as they’re moving slowly
What is brownian motion
The random motion of particles in liquids and gases
What is diffusion
The random movement of liquid and gas molecules from regions of high concentration to regions of low concentration
What are 3 chemical factors affecting rate of diffusion
- molecular mass - heavier molecules diffuse slower\
- temperature - higher temperature increases rate of diffusion
- Concentration gradient - the difference in concentration between the two regions
Use and example use of filtration
Insoluble solid from liquid or solution
Sand/ Seawater
Use and example use of Decanting
Two substances, one denser and insoluble in the other
Petrol/ water
seawater/ sand
Use and example use of evaporation
non-volatile solid from volatile liquid
salt/ seawater
Use and example use of distillation
Volatile liquid from non-volatile substance
water/seawater
water/ink
Use and example use of fractional distillation
Large difference in boiling points
Ethanol/water
components of crude oil
Use and example use of sublimation
one solid sublimes
iodine/sand
Use and example use of diffusion
gases diffuse at different rates
CO/CH4
Use and example use of magnetism
One substance is magnetic
Iron/Aluminium
Nickel/copper
Impurities in a substance ______ melting point and _______ boiling point
lower, raise
What is a standard solution
A known amount of substance dissolved in a known volume of solution
Concentration formula
C = n/v
Phenolphthalein colour in acid and alkali
acid: colourless
alkali: red
Bromothymol blue colour in acid and alkali
acid: yellow
alkali: blue
litmus colour in acid and alkali
acid: red
alkali: blue
Methyl orange colour in acid and alkali
acid: red-orange
alkali: yellow
Meaning of ductile
Ability to be made into a wire
Meaning of malleable
How easy it is to bend
Meaning of tensile
Ability to be stretched
Reactivity series in order (most-least)
K Na Ca Mg Al (Carbon) Zn Fe Pb (Hydrogen) Cu Ag
Solubility of nitrates
All nitrates are soluble
What are the 2 thermally stable hydroxides and carbonates
K and Na
What are the 5 reactions in extraction of iron
C + O2 -> CO2 C02 + C -> 2CO Fe2O3 + 3CO -> 2Fe +3CO2 CaCO3 -> CaO + CO2 CaCO3(s) + SiO2(s) -> CaSiO3(l) + CO2
Elements more reactive than Carbon are extracted by ________________
electrolysis
Zinc is extracted by __________
Adding coke (carbon)
In general, what is formed at the cathode
metals, hydrogen
In general, what is formed at the anode
non metals
What are the three products of the electrolysis of brine
Hydrogen, caustic soda, chlorine
What is the diaphragm made of and what does it do`
Asbestos,
Prevents solution from passing from cathode side into anode side.
What is the name of aluminium ore
bauxite
What are 2 reasons why cryolite is added
1) Lowers melting point
2) conducts electricity better
3 examples of exothermic reactions
Combustion
Neutralisation
Respiration
2 examples of endothermic reactions
Thermal decomposition of calcium carbonate
When we eat sherbert sweets
What is the difference between high and low concentrations called
concentration gradient
Formula for Rf value
Distance travelled by substances / Distance travelled by solvent - should always <1
What strength are the intermolecular and intramolecular bonds in simple molecular substances
Weak intramolecular
strong intermolecular
What are allotropes
molecules of same element(s) but different structure
What is raw iron ore called
Haematite
In an aqueous solution metals less reactive than hydrogen will form at the ___________
Cathode because they’re more easily reduced.
3 steps in electrolysis of brine
1) Hydrogen ions go to cathode and get reduced to form H2 Gas
2) Chloride ions are oxidised at anode to form yellow/green Cl2 Gas
3) Na+ and OH- forms NaOH
Use of chlorine
Bleach, PVC
Use of hydrogen
Fuel, Margarine
Use of sodium hydroxide
Soap, paper.
Why can’t aluminium be extracted using carbon
It is more reactive than carbon.
______Changes are traditionally not reversible, while ______Changes usually are.
Chemical
Physical
What is collision theory
- Particles must collide before a reaction takes place
- Not all collision leads to reaction
How to catalysts increase rate of reaction
They create a new path for reaction which requires less activation energy
Why are catalysts often used in industry
- Reaction takes place at lower temperature-saves energy
- Enables different reactions to be used-better atom economy
- Important in production of polyethene, H2SO4, NH4, Ethanol
- Can reduce pollution
What does equilibrium mean
Both forward and backward reaction have same rate of reaction
What is Le Chateliers principle
When a change is applied to a system in dynamic equilibrium, the system reacts to oppose the change
Conditions of the Haber process
Pressure: 20,000Kpa
Temp: 380-450*C
Catalyst: Iron
Haber process formula
N2(g) + 3H2(g) 2NH3(g) DeltaH = -92KJ/mol
Uses of ammonia
Fertilizers
Explosives
Why must acids be aqueous to be considered an acid
Because they need to donate their proton
Stronger acids ____ more than weak acids
dissociate
acid + metal ->
metal salt + hydrogen gas
acid + metal oxide -> `
metal salt + water
acid + metal hydroxide ->
metal salt + water
acid + carbonate
metal salt + carbon dioxide + hydrogen gas
acid + hydrogencarbonate ->
metal salt + carbon dioxide + water
Hydronium Ion formula
H3O+
Why do strong bases form OH- ions more easily
because they associate easily into their ions
What is residue
solid formed after filtration
what is filtrate
liquid formed after filtration
What type of reaction forms salts
neutralisation
Why can you not apply direct heat to salt after filtering
can cause damaged crystals and/or by products
To obtain a insoluble salt from solution ?
filter it out and dry in warm over
to obtain soluble salt from solution?
evaporate liquid away in evaporating dish
2 things members of a homologous series have in common
- Same general formula
- Similar chemical properties
saturated hydrocarbon means:
cannot have any more hydrogen atoms added
As number of carbons in ALKANES increases:
B.P increases
Viscosity increases
Flammability decreases
In less flammable things, activation energy is_____
greater
Test for alkene:
bromine water turns from orange/brown to colourless
What is cracking
splitting up of fractions in long hydrocarbon chains to form smaller hydrocarbon chains.
done by heating fractions to high temp then passing vapour over suitable catalyst.
What are the conditions for cracking
600-700*C
silica or alumina catalyst
What is hydration
Addition of water in the form of steam to alkenes to form alcohols
conditions for hydration
Catalyst - phosphoric acid
Pressure - 60-70 atm
temp - 300*C
What is hydrogenation
Addition of hydrogen to alkenes to form alkanes
conditions for hydrogenation
Catalyst - nickel
temp - 130*C
what is addition of hydrogen halides
addition of hydrogen halides to alkenes to form haloalkanes.
The hydrogen will attach to one side of the double bond and the halogen to the other.
Markovnikovs rule
The hydrogen prefers to bond with the carbon which already has more hydrogens.
“the rich get richer”
What is electronegativity
The ability of an atom to pull its valence electrons towards its nucleus.
What is esterfication
combining of carboxylic acids and alcohols to form esters using sulfuric acid as a dehydration agent.
Difference between aldehydes and ketones
Aldehydes have C=O bond on the end of chain, while ketons have C=O bond in middle of chain.
