C4-C6 Questions Flashcards
Suggest other factors, apart from atom economy, that must be considered when deciding which reaction pathway to choose for the manufacture of hydrogen.
Percentage yield
Usefulness of by products
Cost of Raw Materials
What is a catalse?
Catalase is an enzyme in the liver which breaks down harmful hydrogen peroxide into oxygen and water.
What are the problems called by mineral deficiency:
Nitrogen
Phosphorus
Potassium
Nitrogen causes poor growth and yellow leaves
Phosphorus causes poor growth and discoloured leaves
Potassium cause poor fruit growth and discoloured leaves
Describe how scientists think an oxygen rich atmosphere developed over time.
As earth could water vapour condensed to form oceans.
Leaving initial atmosphere of CO2
Photosynthetic organisms began to make O2 so reduces CO2 amount
Increase in oxygen and nitrogen levels.
Describe the enhanced greenhouse effect and the problems it may cause
CO2 is released into the atmosphere by the combustion of fossil fuels
Methane is released into the atmosphere from paddy fields and cattle.
Additional greenhouse gases by human causes enhanced greenhouse effect.
It can cause ice caps/glacials to melt as well as a change in global temperature.
What is bioleaching?
A method of extraction for low grade ore.
Bacteria oxidise Iron (II) and sulfide to produce sulphuric acid. This acid can be used to extract copper from copper ores
Write about the advantages and disadvantages of bleaching of bioleaching
Advantages is that it is cheaper , low grade ore can be used, bacteria occur naturally.
Disadvantages - very slow
Describe how plants are used in phytoextraction to extract metals.
Plants absorb dissolved ions through their roots
Metal ions accumulate in roots / shoots / leaves
Crop is planted in soil containing a low-grade ore
A ‘complexing agent’ is added so the plants absorb the metal ions more easily
Plants (are harvested and) burnt to produce an ash with high concentration of the metal
Metal is extracted from ash
Phytoextraction is a more carbon neutral activity than traditional mining. Explain why
Burning plants release CO2 but plant absorb CO2 for photosynthesis
What are the stages for life cycle assesment
Extract raw materials
Manufacture from raw material
Transport
Dispose
Describe the four processes and how the greenhouse effect occurs.
radiation/heat from the Sun reaches the (surface of the) Earth
radiation is absorbed by the (surface of the) Earth
some energy/heat or infrared (radiation) go back into space
some energy/heat or infrared (radiation) is absorbed/trapped by greenhouse gas (molecules) in the (Earth’s) atmosphere
Heat from greenhouse gas (molecules) returns to Earth warming the (surface of the) Earth
A student has an unknown solution. She thinks that the solution contains Copper II ions and bromide ions.
Describe the chemical tests she does this to confirm the presence of the two ions in the solution.
Copper (II) ions can be tested by using sodium hydroxide, and if present it will be a blue precipitate.
Bromide ions can be tested by using aqueous silver nitrate and dilute nitric acid. It gives a cream precipitate.
What is meant by the term dynamic equilibrium ?
Refer to both concentrations and rate of reaction in your answer.
Dynamic equilibrium is when the rate of the forward reaction is equal to the rate of the backward reaction.
Concentration of reactants and products do not change.
The Haber process is used to manufacture ammonia. Explain the importance of the Haber process in agriculture.
Endless supply of starting material as Haber Process turns atmospheric nitrogen into ammonia.
Ammonia is used to make fertiliser which increases crop yield.
What are the conditions used for Contact Process?
450 degrees
normal atmospheric pressure or 10 atm
Vanadium Pentoxide catalyst
What is needed for corrosion
Contact with oxygen and water
Describe what observations you would make when a small piece of potassium is added to a trough of water.
Potassium moves around rapidly on the surface of the water. The gas would ignite and produce a lilac flame.
What are the proportion of gases in the present day
Nitrogen - 78%
Oxygen - 21%
CO2 - 0.04%
Describe how the percentages of the gases in the atmosphere have changed between 3 billion years ago and 2 billion years ago.
The amount of nitrogen has dropped because the levels of oxygen increased.
There was no oxygen 3 billion years ago but 2 billion years ago 10% of the atmosphere was oxygen due to photosynthesising plants.
The amount of carbon dioxide remained relatively constant due to volcanic activity.
2 disadvantage of phytoextraction
Very slow and burning plants can release contamination.
How to test for carbonate ions.
Add hydrochloric acid - bubbles are formed.
Test the gas given off for CO2 by passing it into limewater. If turns cloudy CO2 is present.
What is contact process and what are the equations.
Contact process is used for making sulphuric acid. S + O2 --> SO2 2SO2 + O2 --> 2SO3 H2O + SO3 --> H2SO4 but SO3 is hazardous so H2SO4 + SO3 --> H2S2O7 (oleum) H2S2O7 + H2O --> 2H2SO4
What are the conditions used for Haber Process?
200 atmospheres
450 degrees
iron catalyst
What is the formula for haber process
N2 + 3H2 –>–< 2NH3
