Chemistry Paper 2- Major Focus Of Exam Flashcards
How can you find the speed of a reaction?
Recording the amount of product formed and reactants used up
Do the fastest rates of reaction have steeper or flatter lines?
Steeper
What must particles do in order to react?
Collide with enough energy
What are the 4 factors that affect the rate of reaction ?
Temperature, concentration, surface area, presence of a catalyst
Explain how increased temperature affects rate of reaction (4)
Particles gain kinetic energy
Move faster
Increased frequency of successful collisions
Increased rate of reaction
Explain the affect of concentration on the rate of reaction (4)
More particles in a fixed volume
Increased frequency of successful collisions
Increased rate of reaction
What factor does pressure act similar to in rates of reaction ?
Concentration
Explain how surface area affects rate of reaction (4)
More particles are on show( exposed)
Increased frequency of collisions
Increased rate of reaction
How can surface area of solid be increase?
Break into smaller pieces
How does using a catalyst increase the rate of reaction?
Lower the activation energy- provide an alternative reaction pathway
What’s the equation for mean rate of reaction?
Rate of reaction= amount of reactant used/product formed/ time
What are the 3 different ways in measuring rate of reaction?
Precipitation and colour change
Change in mass
Volume of gas given off
Describe the practical to measure rate of reaction involving sodium thiosulfate
Add set volume of sodium thiosulfate to flask
Place flask on paper with a cross
Add some HCL and start timer
Watch black cross disappear and time how long it takes
What are some control variables in the sodium thiosulfate experiment
Volume of sodium thiosulfate and HCL
Same cross
Same person
What can you draw to find the reaction rate at a particular point?
Draw a tangent
When is equilibrium only reached ?
If the reversible reaction takes place in a closed system
What 3 factors does the position of equilibrium depend on?
Temperature, pressure, concentration
What do reversible reactions try to do?
Counteract changes
If equilibrium lies to the right, is the concentration of products greater or less than of the reactants
Greater
If you decrease the temperature, which reaction will be favoured ?
The exothermic direction
If you raise the temperature, which way will the equilibrium move?
In the endothermic direction
What does changing pressure only affect ?
A reaction involving gases
If you increase the pressure, where will the equilibrium shift?
To the side with fewer gas molecules
If the pressure is lowered, what direction does the equilibrium move?
In the direction with the most gas molecules
If you increase the concentration of reactants what will the system try to do to counter act this?
Make more products
When measuring rates of reaction, describe the change in mass method
When the gas is released, the mass disparaging is measured on a mass balance
Take measurements at regular intervals and plot a graph
What is a disadvantage of the change in mass method?
A gas is released straight into the room
Why is the change in mass method the most accurate?
Mass balance is very accurate
Describe the measure of measuring the volume of gas given off when measuring rates of reaction
Use a gas syringe, and measure volume of gas given off
What is an issue with the choke of gas given off method?
If the reaction is too vigorous, you can easily blow the plunger out the end of the syringe
What is a reversible reaction ?
Where the reaction can go forwards/backwards
What is equilibrium?
When the forward and backwards reaction happen at the same rate and the same time
Where can we find crude oil?
In rocks
How is crude oil formed?
Over millions of years of remains of plankton
What is crude oil a mixture of?
Hydrocarbons
What are hydrocarbons molecules made up of?
Hydrogen and carbon atoms
What are hydrocarbons classified as?
Alkanes
What is the general formula of alkanes?
CnH2n+2
Give 4 alkanes
Methane
Ethane
Propane
Butane
Are alkanes saturated or unsaturated?
Saturated
Why are alkanes saturated?
Carbon atoms are fully bonded to hydrogen atoms
What is another word for viscosity?
Thickness
Are long chain hydrocarbons very viscous or not much?
Very viscous
What does flammability tell us?
How easily a hydrocarbon combusts
Are long chain hydrogens flammable or not very flammable
Not very flammable
Do long chain hydrocarbons have high or low boiling points?
Very high
When do hydrocarbons release energy?
When they are combusted
In the combustion of hydrocarbons, is carbon and hypertension reduced or oxidised?
Oxidised
When a combustion reaction produces CO2 and water, it is incomplete or complete?
Complete
In fractional distillation, what is crude oil separated into?
Fractions
What do fractions contain?
Hydrocarbons with a similar number of carbon atoms
Describe the steps of how fractional distillation works
Crude oil heated Hydrocarbons turns into a gas Vapour fed into fractionating column Vapour rises up the column Hydrocarbons condense when they reach their boiling point Liquid fractions are removed
Is the column hottest at the top or bottom?
Bottom
Are long chain hydrocarbons removed at the top or bottom of the column?
Bottom
Where and how are very short chain hydrocarbons removed in the column?
Right at the top, and don’t condense- they leave as gases
What is petrol and diesel used for?
Fuelling cars
What is kerosene used as?
Jet fuel
What is heavy fuel oil used for?
Powering ships
What is liquidised petroleum gas used in?
Camping stoves
What are some fractions used as for the petrochemical industry?
Feedstock
What is a feedstock?
A chemical used to make other chemicals
Give 4 examples of what feedstock fractions are used for
Making solvents
Lubricants
Detergents
Polymers
What type of bonds do alkanes have between their carbon atoms?
Single covalent
What is one reason why long chain hydrocarbons aren’t used as fuels?
They aren’t very flammable, so don’t combust well
What does cracking convert?
Long chain hydrocarbons to short chain hydrocarbons
What are the conditions for catalytic cracking?
High temperatures and a catalyst
What are the conditions for steam cracking?
High temperature and steam
What does cracking make?
Alkenes
What type of bond do Alkenes have between carbon atoms?
Double covalent
Why are Alkenes useful?
Used to make polymers
Used as a starting material for other useful chemicals
Are Alkenes more or less reactive than alkanes?
More reactive
How do you test for Alkenes?
Add bromine water, shake it, and it will turn colourless from an orange colour
What percent is our current atmosphere made up of nitrogen?
78%
What percent is our atmosphere made up of oxygen?
21%
What kind of gases form a very little proportion of our atmospheres gases?
CO2, water vapour, noble gases like argon
In the early atmosphere, what do scientists think released the gases that formed it?
Volcanoes
What is an example of a gas released by volcanoes in our early atmosphere?
Water vapour
How did oceans form?
Water vapour condensed
Besides water vapour, what other gas did volcanoes release lots of?
Carbon dioxide
TRUE or FALSE? In the early atmosphere, the atmosphere consisted of lots of oxygen and little CO2
False- it consisted mainly of carbon dioxide and little oxygen
Besides CO2 and water vapour, what other gases(in smaller amounts) did volcanoes release?
Nitrogen, methane and ammonia
Compare the differences of the earths early atmosphere and the current one
Early atmosphere had high amounts of CO2, whereas the current atmosphere has very little
Current atmosphere contains lots of oxygen, whereas the early atmosphere had very little
What gas dissolved in oceans to form a weak acid?
Carbon dioxide
How did precipitates form in the sea?
The weak acids reacted with minerals
Over time, what did the precipitates form?
Sediments of carbonate rock on the sea bed
What was some of the carbon dioxide in the sea used to make?
Coral and shells or organisms like mussels
When the mussels died, what type of rock formed?
Sedimentary rock limestone , removing Co2
How did oxygen first enter the atmosphere?
Around 2.7 billion years ago, algae formed in the oceans, and photosynthesis produced oxygen
Over time what increases the amount of oxygen in the atmosphere?
Evolution of plants
What’s the final reason why the level of CO2 levels fell?
Carbon dioxide was taken in via photosynthesis, becoming trapped in fossil fuels
Are fossil fuels renewable or non renewable?
Non renewable
How is coal formed?
From the remains of ferns and trees, and if in marshy conditions, don’t decompose.
Over time, the plant remains is covered with sediment and is compressed
High temperature and pressure produces coal
Ultimately, what are the 2 factors that produce coal?
High temperature and pressure
How is crude oil formed?
From plankton, that die and settle in mud on the sea bed Over time they are compressed Heat and pressure converts them Into Crude oil
How is natural gas formed(simply)
From
Plankton
Where does natural rubber come from?
Sap of a tree
What is synthetic rubber produced from?
Crude oil
Are fossil fuels finite?
Yes
Are metals finite?
Yes
Give an example of a renewable resource
Wood
What is a renewable resource?
A source that can be replaced as quickly as it is used
What does drink water need to have and not have?
Needs it have dissolved minerals, but no harmful microbes
What is potable water?
Water safe to drink
What does pure water contain?
No dissolved substances
Does potable water contain dissolved substances?
Yes
In the UK, what type of water provides most of our potable water?
Rain water
How to we obtain potable water?
Choose a source of fresh water
Pass water through filter beds
Sterilise it using chemicals
What’s the purpose of the filtration stage in obtaining potable water?
The remove solid materials like leaves
What’s the purpose of the sterilisation stage in obtaining potable water?
Kill microbes
What chemicals can we use for sterilisation?
Chlorine, ozone and UV light
In countries where water is scarce, how can potable water be produced?
By desalination
What does desalination reduce?
The levels of dissolved minerals down to a suitable level
What are 2 forms of desalination?
Distillation and reverse osmosis
What is a disadvantage of desalination?
Require huge amounts of energy- very expensive
What does waste water contain a large amount of?
Organic molecules
Besides organic molecules, what else does waste water contain?
Harmful microorganisms
What’s the first stage when doing waste water treatment?
Screening
What does screening involve?
The sewage passing through a mesh
What does screening remove?
Solids and pieces of grit
What’s the next stage after screening in waste water treatment?
Sedimentation
What does sedimentation involve?
Sewage settles in a tank- produces a liquid efficient and solid sludge(it sinks)
What is the sludge taken away and digested by?
Anaerobic bacteria
What can anaerobic bacteria produce when digesting solid sludge?
Biogas- can be burned for electricity
Fertilisers for farming
How do the aerobic bacteria digest the organic molecules and harmful microorganisms of the liquid effluent?
Air is bubbled through it- providing oxygen
After aerobic bacteria digests it’s harmful microorganisms, where can the liquid efficient be discharged into?
Nearby rivers or the sea
What’s the easiest way to
Produce potable water?
By using ground water
What’s a disadvantage of using aquifers for probable water?
Can be polluted by fertilisers from nearby farms
Is ground water potable?
Yes, once it’s been treated with chlorine
Why don’t we usually produce potable water via waste water treatment?
Requires many purification steps
What can copper be used in?
Electronic equipment
Why do we have to start to extract copper from low grade ores?
Copper
Ores are becoming scarce
Simply, what happens in phytomining?
Plants are grown on land containing the metal compound we want
In phytomining what do the plants do?
They absorb the metal and concentrate it in their tissue
How do we extract copper once the plants have it concentrated in their tissue?
We harvest it and burn them
Extract copper from the ash that contains a high concentration of copper
What does bio leaching use?
Bacteria
What happens in bioleaching?
Bacteria are mixed with the low grade ore
Bacteria carry out chemical reactions, producing a leachate
The leachate contains the metal
In the case of copper compounds, how can we extract it?(2 ways)
Displace it using iron
Electrolysis
What do both phytomining and bioleaching allow us to?
Economically extract metals from low grade ores
What’s an advantage of phytomining and bioleaching?
Don’t involve digging or transportation of rock
What can ammonia be used to make?
Nitrogen-based fertilisers
What is ammonia produced by?
The haber process
What’s the equation to form ammonia?
Nitrogen+ hydrogen= ammonia
Where can nitrogen be extracted to make ammonia?
In the air
How can hydrogen be produced?
Reacting methane with steam
What are the conditions for the haber process?
450 degrees
200
Atmospheres pressure
Iron catalyst
What type of reaction is the haber process?
Reversible
How can we increase the yield of
Ammonia?
Cool the ammonia to turn it into a liquid
What can we do to the unteaches nitrogen and hydrogen?
Recycle it
What’s the forward reaction of the haber process?
Exothermic
If we cool the temperature to increase yield, what does that result in?
A slow reaction
Why is 450
Degrees a compromise temperature?
We get a relatively fast rate and relatively high yield of ammonia
What does the iron catalyst do?
Increase the rate of reaction
Besides producing a lower yield, why don’t we use a very high temperature?
Very expensive
What do we settle on a compromise pressure of
200
Atmospheres?
High pressure is expensive and dangerous
What effect does the iron catalyst have on the position of equilibrium?
No effect
What do fertilisers do?
Replace elements in farming
What do NPK fertilisers contain compounds of?
Nitrogen, phosphorus and potassium
Where are NPK fertilisers produced?
In large industrial facilities
Compounds containing nitrogen, phosphorus and potassium improve what?
Agricultural productivity
What are NPK fertilisers?
Formulations of different salts
What do the salts in NPK fertilisers contain?
The required percentage of each element needed by the plants
What’s the main compound of nitrogen in NPK fertilisers?
Ammonium nitrate
How do we make ammonium nitrate ?
Use ammonia produced by haber process and use it to produce nitric acid
React the ammonia and nitric acid
Where does the potassium on NPK fertilisers come from?
The salts potassium chloride or potassium sulfate
How can potassium chloride or potassium sulfate be extracted?
By mining
How can ammonium phosphate be formed?
By treating phosphate rock with nitric acid that produces phosphoric acid
Neutralise acid with ammonia
How can we make a mixture of calcium phosphate and calcium sulfate?
By treating phosphate rock with sulfuric acid
What is a mixture of calcium phosphate and calcium sulfate called?
Single superphosphate
How can we make triple
Superphosphate?
Treating phosphate rock with phosphoric acid
What we do in school
Labs to make ammonium nitrate safe to work with?
Use dilute solutions of ammonia and nitric acid
What do we do in duster to
Make ammonium nitrate compared to school labs?
Ammonia used as gas
Acid concentrated
Why is making ammonium nitrate in industry more dangerous that the school?
Reaction is very exothermic
In a school lab, what do we produce?
Crystals used a water bath and a Bunsen burner- requires lots of energy
In industry, what is some of the energy for evaporation provided by?
The exothermic reaction earlier
What’s the process called in a school lab?
A batch process
In industry, what is the chemical produced by?
A continuous process
Describe the steps to carry out a flame test
Place small
Amount of chemical into a wire mounted in a handle
Place end in blue Bunsen burner flame
What colour flame does lithium produce?
Crimson red
What colour flame does sodium make?
Yellow
What colour flame does potassium make?
Lilac
What colour flame does calcium make?
Orange-red
What colour flame does copper make?
Green
What are some disadvantages of flame tests?
Colour is difficult to distinguish if low conc of metal
Sample containing mixture of metal can mask colour
What’s another technique instead of flame tests?
Flame emission spectroscopy
Describe how to carry out flame emission spectroscopy
Place sample of metal in solution into a flame
Light given out passes into a spectroscope
This converts light into a line spectrum
What are the positions of the lines in the spectrum specific to?
The given metal
What else can flame emission spectroscopy tell us of the metal?
It’s concentration
What does intensity of lines show?
Concentration
What is flame emission spectroscopy an example of?
An instrumental method
What are 3 advantages of instrumental methods?
Rapid
Sensitive
Accurate
States the names of 2 of the gases that made up the earths early atmosphere
Nitrogen and ammonia
Describe how chromatography works
Separates mixtures
Identifies different substances
Solvent will move up paper
Leaving spots on the paper
Describe a method to investigate how change in temp affects rate of reaction between calcium carbonate and hcl
10cm3 of HcL and 0.5 mol of hcl Given mass of Caco3 Repeat for at least 3 diff temperatures Place reactants in flask Place on scales Measure mass after mixing Cotton wool bung to let gas out Measure mass every 30 seconds Plot graph of mass against time
How can the disappearing cross practical be improved?
Use a colorimeter
Describe why a test resulted in a orange flame when o knew the metal contained sodium
Impure sample
Organs flame Bunsen burner
Define crude oil
Mixture of different lengths of hydrocarbons
Why can’t you use a mixture of petrol and diesel in cars?
They are different boiling points as they are different length hydrocarbons
This can cause issues if the fuel is heated to a wrong temperature
Explain the need for cracking
More long hydrocarbons produced than needed
High demand for short hydrocarbons but little produced
Explain the effect a catalyst has on equilibrium
No effect
Speeds up both forwards and reverse direction
How can we determine the mass of salt dissolved in a sample?
Measure mass of whole sample using a basin
Evaporate water and measure mass of basin now and determine difference
Compare reactions to produce ammonoium nitrate in industry and in the lab
Industry- high concentrations , exothermic reactions
Lab- reactions carried out by titstion and crystallisation
Lower concentration of reactants
Why isn’t crystallisation used in industry?
Slow
Why can’t phosphate rock be used as a fertiliser directly?
It’s insoluble, so plants can’t absorb it directly
Plan investigation to show presence of lithium ions and carbonate ions in tablet
Dissolve tablet in water Clean metal wire Dip wire into compound Place in blue flame Observe crimson flame
Add HCL
Bubble gas through limewater
Limewater goes cloudy
What name is given to mixtures like tablets
Formulations
Suggest 1 property of a smart polymer that is different to that of an ordinary one
Can return to original shape
Explain why organisms couldn’t have evolved in the early atmosphere
Little oxygen
Photosynthesis hasn’t occurred
Oxygen using organisms can’t evolve
Explain how methane keeps our planet warm
Allows short wave radiation to pass through and is remitted as long wave radiation
Methane absorbs and traps this radiation
What is in water filters that removes the hardness from water?
Hydrogen ions
Suggest why water filters used in homes contains particles of silver
Preventer growth of microbes
Benefit if drinking hard water
Maintain strong bines
Why does the solution become cloudy when sulfur is formed
It’s a precipitate
Suggest how ammonia is supersets from the other gases
Cools and liquifies to a lower temp than it’s boiling point
What happens to gases from the reactor
Ammonia is cooled and liquefied
Nitrogen and hydrogen is recycled
Suggest why conditions used to produce ammonia are a temp of 450 and pressure of 200
Reaction is reversible
Forward reaction is exothermic, so increases temp= lower yield
Lower temp slows rate of reaction
Higher pressure increases yield as forward reactions produces fewer gas molecules
Higher pressure uses lots of energy so is expensive
Adv of phytomining
Reduces need to obtain new ore by mining
Conserved limited high grade ores
Disadvantage of phytomining
Slow
Land availability is limited
Plan investigation for chromotogrosht and calculate rf value
Draw pencil like on paper Stop food colouring on line Place solvent and paper ik besker so paper is in solvent Solvent below pencil line Allow solvent to rise up to the top Mark solvejt front Calculate rf
Why is polyethene easier to recycle than teurmosetting polymers
Easily melted and reshaped
What 2 compound each contain 2 of elements in npk fertilisers
Potassium nitrate and ammonium phosphate
Eval 2 methods for producing a large mass of ammonium nitrate
Industrial- continuous process and quicker
Lab- small scale and slower and batch
Why is recycling scrap copper sustainable than processing copper ores
Less waste produced
Less energy used
Conserved ores
Explain how phytomining works
Grow plants Plants absorb metal compound Harvested and burned Ash reacts with acid Copper displaced using iron
Disadvantage of bioleaching
Produce toxic substances
What 2 apparatus could you find rate if production of hydrogen gas with
Gas syringe
Stopwatch
Conditions for rusting
Water and air
Why does a nail containing a coating of paint not rust?
Paint is a barrier
Why does a nail rust with a coating of stainless steel
It’s resistant to corrosion
Why does fixing magnesium onto some ships prevent it from rusting?
Magnesium is more reactive than iron so acts as sacrificial protection
Why do aluminium window frames not corrode after they are made
Coating of aluminium oxide
Protects metals
What are glass fibres used in
Reinforcement
Why is an outer skin added to the polystyrene core?
Harder
Tougher
Suggest why the demand for ammonia has increased
World population increased
Demand for fertiliser increased
Name given to a useful product such as methylated spirit
Formulation
Use of formulation
Solvent and fuel
Describe how ethanol is produced from sugar solution
Fermentation
Add yeast
Warm or anaerobic conditions
Gas produced when sodium is added to ethanol
Hydrogen
The percentages of co2 and o2 have changed from earths early stompshere to our atmosphere today, explain the processes that led to these changes
CO2 decreased Volcanoes released water vapour This condensed to form oceans Carbonates produced sediments and carbon become locked up in these sediment rocks Oxygen increased Plants evolved Absorb co2 By photosynthesis Released oxygen
Why are scientists not certain about the oerventage of each gas in the earths early atmosphere
Limited evidende
What’s 2 potential mistakes of chromatography
Start like draw in ink
Ink dissolves and runs in solvent
Water used as solvent
Colours won’t move
If a chromotography paper only has one dot, what can we conclude?
It has one colour
Suggest why maximum allowed % of CO has been decreased for newer cars
CO is toxic
Greater public awareness regarding pollution
Describe how oxides of nitrogen are produced when preform is burned in car engines
Nitrogen from air reacts with oxygen from air at high temperatures
2 effects of atmospheric pollution that are reduced by using catalytic converters
Acid rain
Global dimming
Explain why increased pressure results in increased rate of reaction
More particles per unit volume
Higher frequency of successful collisions
Why doesn’t melamine melt when it’s heated
It’s a thermosetting polymer so contains cross links
Why did proportion of processed solid sludge used as fertiliser increase?
Increased demand for food
Landfill space running out
Compare Ethene and ethane
Both are hydrocarbons and contain 2 carbon atoms
Both have covalent bonds
Ethane contains a single carbon bond whereas Ethene contains a double carbon bond
Ethene de colourises hormone water whereas ethane doesn’t
Ethene is more reactive
Bruh react with oxygen in complete combustion
Suggest why only 2 spots are seen on the chromatography paper despite the ink containing more than 2 compounds
Some of compounds are colourless
Describe how ceramic food plates are produced from clay
Clay is shaped and heated in a furnace
Explain how soot is formed
Incomplete combustion due to insufficient oxygen
Explain how reducing the amount of sulfur in fossil fuels reduced erosion of limestone
Sulfur reacts with oxygen to form sulfur dioxide
Less sulfur dioxide emitted
Less acid rain
Limestone reacts with acid rain
2 naturally occurring polymers produced from glucose
Starch and cellulose
Describe the shape and structure of dna
2 polymer chains
Four nucleotides
Double helix
Why is it more difficult to produce drinking water from waste water than water in lakes
Water needs more stages of treatment due to more microbes and organic matter
Compare the polymerisation reaction to produce polyethene with the polymerisation reaction used to produce a polyester
Polyethene is produced by addition whereas polyester by condensation
Polyethene produced by Ethene whereas polyester from a carboxylic acid and alcohol
Polyethene is only product
Formed whereas polyester waste is also made
Explain how different dyes are separated by paper chromatography
Solvent moves through paper
Different dyes have different solubilises in solvent
Different attractions to paper
So carried different distances
Explain in terms Dk particles how and why rate of reactions changing during faction of calcium carbonate with HcL
Acid particles used up
Less conc of reactants
Fewer frequency of successful collisions so rate if red films decreases
Compare Alkenes with alkanes due to their flames
Alkenes burn in a smokier flame
What was reacting an Alkene and hydrogen make?
Alkane
When you react and Alkenes with water what do we produce
Alcohol
What’s a condition for a hydration reaction
Water just be in the form of steam with high temp and pressure
Have can we increase yield of ethanol
Any I reacted Ethene and steam are passed back through catalyst
If we ready propene and chlorine, what do we make?
Dichloroproane
Formula for methanol
CH3OH
Formula for ethanol
C2H5OH
2 advantages of producing ethanol by fermentation
Low temp means doesn’t require lots of energy
Sugar comes from plants so is renewable
Disadvantage of producing ethanol by fermentation
Does require lots of energy as we jeee to purify aqueous ethabol
Alcohols are…
Soluble in water and form neutral solutions
As number of carbon signs in alcohol increases, what happens to solubility?
Decreases
What products do we form when we react ethanol with sodium
Sodium ethoxide and hydrogen
What do we form when we react ethanol with an oxidising agent
Ethanoic acid and watsd
Structural formula for methanoic acid and ethanoic acid
HCOOH
CH3COOH
Why are csrboxykic acids weak
Only partially ionise in aqueous solutions
When we react ethanoic acid with sodium carbonate what do we produce
Sodium Ethanoic co2
And water
When we react a carboxylic acid with an alcohol what do we make
An ester and water
What catalyst is used when we react ethanol with Ethanoic acid
Sulfuric acid
Do the polymer have single or double carbon bond
Single
In addition polymers what does the repeating unit have the same atoms as
The monomer(eg Ethene)
Where are addition polymers formed from
Alkenes
How can the problem of reproducibility be reduced
Use a colorimeter or same printer cross
Explain how w measure the volume of gas practical
Use a measuring cylinder to place know vol of HcL in flask
Attach flask to bung and delivery tube
Place delivery tube in container filled with water
Place upturned measuring cylinder also filled with water over delivery tube
Add strip of magnesium to HcL
Measure vol of hydrogen gas in measuring cylinder every 10s
Repeat using diff concs of HcL
