chemistry C6-C10 Flashcards
what does rates of reaction mean
how fast the reactants are bieng used up
formula for rate of reaction
reactants/time taken or products/time take
what does collision theory mean?
for particles to react, they need enough activation energy
4 factors that affect rate of reaction
1)temperature
2)concentration
3)surface area
4)catalyst
what happens when you increase temperature in a reaction
the particles gain energy which allows them to move faster and hence collide more which gives faster rate of reaction
what happens when you increase concentration in a reaction
there’s more particles per unit of volume which allows frequent collisions
what happens when you increase surface area in a reaction
will allow a higher rate of reaction as the increased area means more space for collisions
what does a catalyst mean
speeds up a reaction but isnt used up
what happens if u add a catalyst in a reaction
provides alternative pathway that decreases the activation energy and allows reaction to happen faster
how to calculate mean rate of reaction
divide the products made by seconds
how to calculate mean rate of reaction at a particular time
1)draw tangent until line hits y-axis
2)draw two lines coming off both ends on the opposite end of the line
3)take the y-axis number the line is touching and divide it by the time the other line reached
what does reversible reaction mean
the reaction that can occur backwards and foward
what is le chateliers principle
The principle that if you change the conditions the position of equilibrium shift to counteract the change
what does equilibrium mean
how many reactant to products particles there are
-if more reactants then equilibrium lies to…
-if more products then equilibrium lies to
1)left
2)right
what does hydrocarbons mean
compound that’s formed from carbon and hydrogen
what are simple hydrocarbons? Alkanes or alkenes?
alkanes
list the first four simple hydrocarbons
methane, ethane, propane,butane
CH4,C2H6,C3H8,C4H10
what is the formula for alkanes
C^nH2+2
what is the group of simple hydrocarbons called? what series?
homologous series
what does homologous series mean
group of compounds that have a similar chemical properties
what are the properties of alkanes
boiling points increase as chains increase
-shorter alkanes are more volatile(evaporate easily)
-shorter alkanes are more flammable
complete combustion formula
hydrocarbon+oxygen—-carbon dioxide+water
is combustion exothermic or endothermic
exothermic reaction
what does fractional distillation mean
heating up different substances which seperate different compounds due to different boiling points
what is crude oil
- a fossil fuel
-mixture of different compounds
-mostly made up of dead plankton
-non renewable resource
Fractional distillation steps
1)heat up oil until most has turned into gas
2)pass the gaseous mixture to fractionating column - which is hot at bottom and cooler on top
3)the oil will get converted into vapours
4)oil with lower boiling points and shorter chains will be collected at the top
5)long chain molecules will be collected at the bottom because of high boiling points
+the ones at the top are most flammable
+the ones at the bottom- least flammablenand useless
what does feedstock mean
raw materials used to provide reactants for an industrial reaction
what does petrochemicals mean
substances made from crude oil via chemical reactions
what does cracking mean
larger chains and hydrocarbons splitting into smaller ones
what type of reaction is cracking
thermal decomposition reaction
Catalytic cracking method
1)heat up long chain hydrocarbons and turn them into gases.
2)have hot powdered aluminium oxide and pass hydrocarbon vapour over powder.
+ as long as hydrocarbons come into contact with catalyst–they split apart into two shorter ones
steam cracking method
1)heat up long chain hydrocarbons and turn them into gases
2)mix them with steam and heat them at high temperatures-causes long hydrocarbons chains to split apart into shorter ones
steps for bromine test for alkenes
-bromine water by itself is orange -when its mixed with alkenes , the solution becomes colourless
-if its mixed with alkanes ,the solution stays orange
what does pure substance mean
contains only one type of compound or element
+melt and boil at specific temperatures
what does impure substances mean
a substance made from more than one compound or element
+melt and boil over range of temperatures
what does formulations mean
mixtures that have been prepared using specific formulas
what is paper chromotography used for
used to separate different dyes in uk
paper chromotography practical steps
1)take filter paper and draw line in pencil
2)put dot of ink on the line
3)fill beaker with shallow amount of solvent
4)put filter paper in solvent-but dont submerge the pencil line
one thing to ensure you get the best result from chromotagraphy paper practical
place lid on top to stop evaporation
what is the pattern called that you have left from paper chromatography paper practical
chromatogram
what is the mobile phase
substance molecules can move in
what is the stationary phase
materials molecules cant move in
what is the Rf value formula
distance travelled by substance/distance travelled by solvent
Test for chlorine
1)take test tube filled with chlorine
2)take blue litmus paper and dampen it into chlorine
+if chlorine is present the blue litmus paper will turn white
How to ensure safety whilst carrying out test for chlorine
- wear mask
-do practical in fume cupboard
Test for oxygen
1)take glowing splint and put into tube filled with sample gas
2)if oxygen present the splint will light up
+glowing splint requires oxygen
Test for hydrogen
1)take burning flame on splint and bring it near a hydrogen filled test tube
2)if hydrogen is present-a squeaky pop will be heard
+because heat energy provides enough heat energy for hydrogen to react with oxygen
Test for carbon dioxide
1)take lime water in test tube- heat up solution
2)if gas is carbon dioxide-the solution will go cloudy
+this is because CO2 and limewater reacrt to form calcium carbonates
what happened on earth for the first billion years ago
-intense volcanic activity
-produced mostly carbon dioxide , water vapour , nitrogen
how were oceans formed?
as water vapours condensed into liquid form
What happened 2.7 million years ago
-plants and algae began to evolve
+they photosynthesised and took in carbon dioxide- the amount of carbon dioxide has decreased—which allowed animals to evolve
-when plants died overtime- they became buried under sediment-which became compressed to make gas, oil,sedimentary rock-this trapped carbon
List three greenhouse gases
carbon dioxide, methane, water
how is global warming bieng increased?
humans are beginning to produce more greenhouse gases which means the concentrations is increasing.This contributes to greenhouse effect
how how carbon dioxide been increased
-deforestation-less photosynthesis
-burning fossil fuels- release carbon dioxide
how has methane been increased
-farm animals produce methane during digestion
-waste releases methane as it decomposes
what does climate change mean
effects on global warming on weather
impacts of climate change
can cause droughts,floods,hurricane
-high temperatures allows ica caps to melt
+as water warms up-volume of water increases which causes seasonal flooding
-animal biodiversity can decrease
what does carbon footprint mean
total amount of CO2 and other greenhouse gases emitted over something entire life cycle
beneifts of carbon cycle
1)shows how environmentally damaging something can be
2)reduces certain emissions
how can you reduce emissions
1)use renewable source
2)use more efficient manufacturing processs
3)government can make more laws or tax more
4)carbon caoture technology
complete combustion equation
hydrocarbon +[plenty of]oxygen===water_carbon dioxide
incomplete combustion equation
ethane+oxygen===carbon monoxide+carbon +water
what can ethane generate
-carbon monixide
-particulates(solid particles of carbon)
what can particulates do?
-if inhaled-can cause respiratory problems
-causes smog which decreases sunlight
what can carbon monoxide do
-if we breath it in-it diffuses into our blood and binds onto hameoglobin-this means theres less oxygen transported around body
-colourless and odourless means it hard to detect
what can sulfur dioide and nitorgen oxide do
breathe them in increases respirtatory problems
-mixs with clouds which can creates dilute sulfuric and initric acid
+causes acid rain which can harm buildings and crops
Life cycle assessments
analyse different stages in prodyct life cycle,to assess impact on environment
what are the four stages of a life cylce assessment
extracting and processing raw materials-manufacturing and packaging-using product- disposing it
how can extracting harm environment
damages local environment
how can processing be harmful to environment
pollutants may be released
how can manufacturing and processing be harmfuk to environment
release of pollutants
-waste products which can release methane
-lots of energy used up
how can using a product be harmful to environment
1)you have to caluclate how much it damages the environemnt
2)how long product is sued for
how can disposing be harmful to environment
-and we dispose in could affect animals
-chemicals may spread
-release of pollutant
-energy used to transportation
limitations of life cycle assessments
-making product involves lots of steps therefore can be hard to find out how much exact energy has been uses for everything
-can be biased to make company freputation look good
what is potable water
water thats safe to drink
what are 3 criteria for potable water
-no micororganisms
-ph level must be between 6.5–8.5
-level of dissolved substnances must be low
steps to get potable water
1)fres water is passed through wire mesh to get rid of big bits
2)passed through sand and grave to filter small bits
3)sterilise water- to kill micro organisms
3 ways to strelise water
-expose to UV light
-expose to ozone
-bubble chlorine gass through it
desalination meaning
extract potable water
+requires lot of energy
+can be expensive
three main sources of waste water
domestic,agriculture.industrial
sewage streatment
1)screening sewage through mesh
2)let sewage sit in settlement tanks to undergo sedimentation- the heavy solids at bottom are called sludge and flowy matter is effluent
3)then you seperate it into different tanks
