Chemistry Paper 2 (Content) Flashcards
What is the equation for rate of reaction?
What are the units for rate of reaction?
- g/s
- cm3/s
- mol/s
What are the factors that affect the rate of reactions?
- concentrations of reactants in solution
- the pressure of reacting gases (pressure only about gases reacting)
- the surface area of solid reactants
- the temperature
- catalysts
What is a catalyst?
- Catalysts increase the rate of reaction by providing a different pathway for the reaction that has a lower activation energy.
- Catalysts are not used up during the reaction
What is a hydrocarbon?
Molecules made up of only hydrogen and carbon.
Draw a graph to show how rate of reaction is affected by concentration or pressure.
- Higher concentration or higher pressure = steeper gradient which means a faster rate of reaction
Draw a graph to show how rate of reaction is affected by temperature.
- Higher temperature = steeper gradient which means a faster rate of reaction
Draw a graph to show how rate of reaction is affected by surface area.
- Larger surface area = steeper gradient which means a faster rate of reaction
Draw a graph to show how rate of reaction is affected by a catalyst.
- With catalyst = steeper gradient = faster rate of reaction
Explain why increasing concentration affects the rate of reaction.
- Increasing the concentration of a solution will increase the rate of reaction
- This is because there will be more particles in the same volume, allowing more frequent and successful collisions per second, increasing the rate of reaction
Explain why increasing pressure affects the rate of reaction.
- For reacting gases, increasing the pressure will increase the rate of reaction
- This is because the same number of particles will take up a smaller space, allowing more frequent and successful collisions per second, increasing the rate of reaction
What is meant by activation energy?
The minimum amount of
energy that particles must have to react
What is a successful collision of particles.
- Particles that collide with enough energy to be able to react
What is an unsuccessful collision of particles
- Particles that don’t have enough energy to react and just bounce off each other
What is crude oil?
- Crude oil is a finite resource found in rocks.
- Crude oil the remains of ancient biomass consisting mainly of plankton that was buried in mud under high pressure and temperature
- It is a mixture of a very large number of compounds (mostly hydrocarbons)
Explain why increasing temperature affects the rate of reaction.
- Increasing the temperature will increase the rate of reaction
- This is because the particles have more kinetic energy and move more
- This causes more successful collisions per second, increasing the rate of reaction
Explain why increasing surface area affects the rate of reaction.
- Increasing surface area of a solid reactant = faster rate of reaction
- This is because more surface area of the particles will be exposed to the other reactant, which means a higher number of collisions per second which means a higher number of successful collisions
What is the general formula for the homologous series of alkanes?
CnH2n+2
What is the general formula for the homologous series of alkenes?
CnH2n
How many carbons does methane have?
1
How many carbons does ethane have?
2
How many carbons does propane have?
3
How many carbons does butane have?
4
What do alkenes react with?
- Oxygen (in combustion)
- Hydrogen
- Water
- Halogens (Bromine, Chlorine, Fluorine)
How do we recognise alcohols from the name?
- Name of substance ends in -ol
What is an alcohol?
- Contains the functional -OH group
What is meant by pure?
- In chemistry, a pure substance is a single element or compound, not mixed with any other substance.
- Pure elements and compounds melt and boil at specific temperatures.
- In the everyday English language, a pure substance can mean a substance that has had nothing added to it, so it is in its natural state, eg pure milk.
What is the test for hydrogen gas?
- Burning or lit splint held at the open end of a test tube of the gas.
- If hydrogen present it will make a squeaky pop sound
What is the test for oxygen?
- Uses a glowing splint inserted into a test tube of the gas.
- If oxygen is present the splint relights in oxygen.
What is the test for carbon dioxide?
- The test for carbon dioxide uses an aqueous solution of calcium hydroxide (lime water).
- When carbon dioxide is shaken with or bubbled through limewater the limewater turns milky (cloudy)
What is the sulfate ion?
SO42-
What is the test for sulfate ions?
- Sulfate ions in solution produce a white precipitate with barium chloride solution in the presence of dilute hydrochloric acid.
When do we use the tangent method to calculate rate of reaction from a graph?
When we have a single number.
When do we use dy/dx (difference in y over difference in x) to calculate rate or reaction from a graph?
When we have two numbers or they have said the mean rate of reaction
What is an enzyme?
Biological catalyst.
Draw a reaction profile for an exothermic reaction with a catalyst and without a catalyst.
When does equilibrium happen?
When a reversible reaction happens in a closed system which stops reactants and products escaping
What is meant by equilibrium?
When the forward and backward reactions of a reversible reaction are happening at exactly the same rate.
What is Le Chatelier’s Principle?
- Predicting the effects of changing conditions on a system at equilibrium
- where the system will respond to counteract the change
What happens if the concentration of a reactant is increased?
If the concentration of a reactant is increased, more products will be formed until equilibrium is reached again.
What happens if the concentration of a product is decreased?
If the concentration of a product is decreased, more reactants will react to make more product until equilibrium is reached again
Draw methane
Draw ethane
Draw propane
Draw butane
Explain the process of fractional distillation.
- Crude oil has a mixture of hydrocarbons
- Crude oil is heated and enters the fractionating column as a gas and rises
- At the bottom of the column it is hotter so larger hydrocarbons condense lower down the column
- Whereas a hydrocarbon with a shorter chain will have a lower boiling point and will condense back to a liquid at the top of the column where its cooler
Why does butane have a higher boiling point than methane?
Larger hydrocarbons have larger surface area contact with each other which means there are more intermolecular forces between larger hydrocarbons and more energy is needed to overcome these forces.
So longer chains of hydrocarbons have higher boiling points.
What do we mean by viscosity?
How easily a liquid flows
High viscosity = thick and flow less easily
Low viscosity = runny liquid
What is the relationship between the chain length of hydrocarbons and viscosity?
- Viscosity also increases with increasing chain length
- Due to the increased intermolecular forces as molecules increase in size
- Longer chained alkanes are useful as lubricants for machinery because they have higher viscosity
What is the relationship between the chain length of hydrocarbons and flammability?
- Smaller hydrocarbon molecules are more flammable and are easier to ignite than larger molecules
- This makes them very useful as fuels, releasing large amounts of energy when they burn
What are the products of complete combustion?
- Carbon dioxide
- Water
What does it mean for a hydrocarbon to be saturated?
- Contains single carbon to carbon bonds only
- and have the maximum number of hydrogens bonded to each carbon
What does it mean for a hydrocarbon to be unsaturated?
- Contains double carbon to carbon bonds
What are the two types of cracking?
- Steam cracking
- Catalytic cracking
What is cracking?
Hydrocarbons can be broken down (cracked) to produce smaller, more useful molecules.
What is the test for alkenes?
Bromine water
Goes from orange to colourless
What are the products of cracking?
Alkane + Alkene
What is the colour of silver chloride?
- Silver Chloride = AgCl
- White precipitate
How is silver chloride made?
Halide ions (e.g. Chloride, Bromide or Flouride - so in this case chloride) in solution produce precipitates with silver nitrate
solution in the presence of dilute nitric acid
What is the colour of silver bromide?
- Silver bromide = AgBr
- Cream precipitate
What is the colour of silver iodide?
- Silver iodide = AgI
- Yellow precipitate
How is silver bromide made?
Halide ions (e.g. Chloride, Bromide or Flouride - so in this case bromide) in solution produce precipitates with silver nitrate
solution in the presence of dilute nitric acid
How is silver iodide made?
Halide ions (e.g. Chloride, Bromide or Flouride - so in this case iodide) in solution produce precipitates with silver nitrate
solution in the presence of dilute nitric acid
What is a halide?
Ions from the halogens
Halogens = Group 7 = Fluorine, Chlorine, Bromine, Iodine
Halogens = NEUTRAL CHARGE
Halide ions = Fluoride, Chloride, Bromide, Iodide
Halide ions = HAVE AN OVERALL CHARGE OF -1 BECAUSE HALOGENS ARE IN G7
What is the carbonate ion?
CO32-
What are the reactions of carbonates?
- Carbonates react with dilute acids and form carbon dioxide
What flame colour is a lithium compound?
Crimson flame
What flame colour is a sodium compound?
- Yellow flame
What is a formulation?
A formulation is a mixture that has been designed as a useful
product.
What is a mixture that has been designed as a useful product called?
Formulation
What are the two phases of chromatography?
- Mobile phase (mobile means movement)
- Stationary phase
What is the mobile phase of chromatography?
Solvent (the thing thats moving up the paper)
What is the stationary phase of chromatography?
Chromatography paper (the stationary equipment - or equipment that stays still)
What is potable water?
Water that is safe to drink
Is potable water pure?
No,
- Potable water is not pure water in the chemical sense because it contains dissolved substances
- For humans, drinking water should have very low levels of dissolved salts and microbes
What are the sterlising agents used for potable water?
- Chlorine
- Ozone
- Ultraviolet light
How is potable water produced in the UK?
- choosing an appropriate source of fresh water
- passing the water through filter beds
- sterilising
What is a renewable resource?
- Renewable resources is those resources which can be replenished or replaced as fast as it is being used up
Basically it wont run out
What is a finite resource?
Finite or non-renewable resources are those that don’t reform quickly enough or don’t reform at all
Basically something that may run out
What are the products when alcohols are burned?
- Combustion reaction
- Products are CO2 and H2O
What type of reaction is an alkene and hydrogen?
- Addition reaction
- Where hydrogen is “added”
- Double bond becomes single carbon to carbon bonds
What type of reaction is an alkene and water?
- Addition reaction
- Where hydrogen is “added”
- Double bond becomes single carbon to carbon bonds
What type of reaction is an alkene and a halogen?
- Addition reaction
- Where hydrogen is “added”
- Double bond becomes single carbon to carbon bonds
What are the percentages of the different gases in the atmosphere?
- 4/5 or 80% Nitrogen
- 1/5 or 20% Oxygen
- very small percentages other gases, including carbon
dioxide, water vapour and noble gases