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