Stuff from chem revision booklet Flashcards
equation for rate of reaction
rate of reaction = change in amount of a reactant or product/time
or
number of successful collisions / time
ways to measure how long it takes for a reaction to finish
how long it takes for…
cross to dissapear (solid sulfur precipitate)
magnesium piece to dissapear
how long it takes to produce a certain amount of gas (?)
if the reaction is exothermic, will the triangle H have a negative sign?
yess
advantages and disadvantages of ethene route to alcohol
fast, efficient, continuous process,relatively pure product
non renewable finite resource
disadvantages and advantages of fermentation
cheap and renewable resource (eg sugar cane)
slow reaction, poor quality products- eg low aqueous concentration <14%
industrial formation of ethanol
made from ethene and steam
high temp, high pressure and phosphoric acid catalyst needed
ethene combines with steam to make ethanol which is used as a solvent
process of fermentation
sugar solution + yeast warmed
airlock keeps air out
yeast respires anaerobically, releasing enzymes to catalyse the breakdown
C6H12O6 -> 2C2H5OH + 2CO2
what is polypropene used for
for plastic crates and ropes, as it is stronger and less flexible than polyehtene
what is polyethene used for
plastic bags and plastic bottles- forms a thin, flexible, transparent film
what is polytetrafluorene used for
non stick pans
what is PVC used for
drain pipes and insultion on electric cables since it is strong, not flexible and doesn’t conduct electricity
how do you calculate RF value
distance travelled by component/ distance travelledby solvent
substance + oxygen ->
oxide
metal + water ->
metal hydroxide + hydrogen
metal + acid->
salt+hydrogen
oxide + acid ->
salt+water
hydroxide+acid->
salt+water
carbonate+acid->
salt+water+co2
hydrogencarbonate+acid->
salt+water+co2
ammonia+acid->
ammonium salt
metal carbonate->
metal oxide+co2
precautions for toxic substances
wear gloves
if gas, use fume cupboard/well ventilated lab
precautions for corrosize substances
wear gloves to prevent burns
precautions for harmful substances
wash hands if spilt
precautions for irritant substances
wear gloves or wash hands if spilt
precautions for flammable substances
keep away from naked flames
precautions for oxidising agents
do not mix with easily flammable substances
what is an oxidising agent?
allows other substances to burn well, will oxidise other substances
precautions for explosive substances
do not use
example of an explosive substance
caesium
precautions for environment damaging substances
do not flush down sink
put waste in a container to be disposed of professionally
name two flammable gases
hydrogen and methane
hydrogen and methane are…
flammable gases
When concentrated, acids and alkalis…
corrosize and can chemically burn skin
halogens such as chlorine are…
toxic
their vapours are poisonous
organic chemicals like ethanol are..
flammable, should be kept away from naked flames
what did JJ thompson do?
passed electricity thru low pressure gas tube
neg electrode emitted beam of neg charged particles.
realised they must’ve come from inside the atom
possible bc electricity
when did JJ thompson discover electrons?
late 1800s
when was the existance of the neutron confirmed?
1932
who confirmed the existance of the neutron?
james chadwick
what did james chadwick do?
confirm existance of neutron in 1932
relative mass of an electron?
1/1860
what happened in 1911?
rutherford concluded positive stuff in atoms must be concentrated in a very small nucleus
discovery possible due to radioactivity
who first suggested that things were made of atoms?
democritus
ancient greek times
what did john dalton propose?
matter is composed of tiny particles called atoms
atoms of a similar element are alike in shape, size and weight but differ from other elements
during chemical changes atoms of different elements unite forming molecules
when atoms combine they do so in definite whole number ratios
when was john dalton?
early 1800s
what is ionic bonding?
complete transfer of one or more electrons from metal to non metal, giving charged ions that electrostatically attract
what is a covalent bond?
the electrostatic attraction between positively charged protons in the nucleus and the negative shared pair of electrons
What is the structure of metals?
Layers of pos close packed metal ions in “sea” of delocalised electrons
Why are metals malleable?
Layers of ions
can slide over each other
Why do metals have high MPs?
v. strong electrostatic attraction between ions+delocalised electrons
lots of energy to overcome
Why do simple molecular substances have low BPs?
only weak IMF between the molecules
these take little energy to overcome
why can’t molecular compounds conduct electricity?
no charged particles that can move
strcture of diamond/graphite
giant lattice of atoms
why do giant covalent structures have high MPs?
many strong covalent bonds between all the atoms that take a lot of energy to break
why do some ionic compounds have higher MPs than others?
the higher the charge the stronger the attraction
How do you calculate the volume of a gas? (dm^3)
moles x 24
Limitations of dot cross representation?
Doesn’t show relative size of atoms or shape of molecule - covalent
does not show how the ions are arranged in a lattice - ionic
Limitations of ball-and-stick representation?
atoms not to scale
do not show where the electrons in the bond come from
makes it look like there are large gaps between atoms
^^ covalent
Limitations of space filling representation?
not always easy to see the 3D shape
Limitations of displayed formula representation?
doesn’t show 3d shape or correct bond angles
Limitations of close packed representation?
difficult to see arrangement of ions
limitations of ionic 2d ball and stick
doesn’t show 3d arrangement
limitations of ionic 3d ball and stick
the ions are actually close together
gives a false image of bond direction; it is only electrostatic attraction
