Overall quick test Flashcards
State the composition of the atmosphere.
78% nitrogen, 21% oxygen, 1% other gases (mainly argon with small amounts of other gases including water vapour and carbon dioxide)
List the stages involved in the most probable theory of the evolution of the atmosphere.
The early atmosphere of carbon dioxide and water vapour formed from volcanoes. Atmospheric water vapour condensed to form the oceans. Photosynthetic organisms used up carbon dioxide and released oxygen. Carbon dioxide dissolved in the oceans and formed sedimentary rocks and fossil fuels.
Name the two natural processes that remove carbon dioxide from the atmosphere.
Photosynthesis and dissolving in the oceans.
Explain why combustion is a type of oxidation reaction.
Combustion is when a fuel reacts with oxygen (to release energy)
What does the term ‘hydrocarbon’ mean?
A hydrocarbon is a compound made only from carbon and hydrogen.
Give 3 ways to reduce pollution from power stations.
Using less electricity, removing sulfur from the fuel being used, removing sulfure dioxide and particulates from the gases released by the power station.
Give 4 ways to reduce pollution from cars.
Any 4 from:
More efficient engines, low-sulfur fuels, catalytic converters, using public transport more, legal limits for emissions
Explain how NO[x] gases are formed. (HT)
Atmospheric nitrogen is oxidised by atmospheric oxygen at high temperatures to form nitrogen monoxide (NO), which is further oxidised to form nitrogen dioxide (NO[2]).
Name 2 natural materials and 2 synthetic materials.
Natural materials = any 2 from: silk, wool, cotton, paper
Synthetic materials = any 2 from plastics such as poly(ethene), polyesters, nylon, PET
Name the process used to separate crude oil into useful hydrocarbons.
Fractional distillation
Explain the link between molecule size and boiling point.
The larger the molecule, the stronger the intermolecular forces and the more energy that is needed to overcome the forces, so the higher the boiling point.
Give a use for kerosene/paraffin.
Fuel for aeroplanes/central heating/camping lanterns
What is the effect on the properties of a plastic of cross-linking the polymer molecules?
Cross-linking makes a plastic stiffer and harder and it increases its melting point
What is a plasticizer and what does it do to the properties of a polymer?
A plasticizer is a small molecule that fits between polymer chains and weakens the intermolecular forces, making the polymer more flexible
What is nanotechnology?
Nanotechnology is the study and manipulation of very small particles
Give an example of how nanoparticles can occur naturally.
In sea spray (also accept ‘particulate carbon produced by combustion of fuels’.)
Name 3 mineral resources found in Britain.
Coal, salt and limestone
Name 3 processes that have been involved in creating Britain’s mineral resources.
Any three from mountain building, erosion, sedimentation, dissolving, evaporation
State 2 things that salt is used for.
Any 2 from as flavouring and preservation in food, to treat roads in winter, as a source of chemicals
Why is excessive salt in the diet bad for you?
It can cause high blood pressure
Name 3 products from the electrolysis of brine (salt water).
Hydrogen, chlorine and sodium hydroxide
What is meant by the term ‘electrolysis’?
Splitting up a liquid or dissolved compound using electricity
Give one use of chlorine.
Any suitable answer: to disinfect water, as a bleach, in the manufacture of plastics
Briefly describe what happens in a life cycle assessment.
Any suitable answer: each part of the life cycle (production of materials, manufacture, use and disposal) is assessed for impact on resources, energy requirements, and environmental impact.
Why are lithium, sodium and potassium all found in the same group of the periodic table? Use ideas about their properties and their electron configurations.
They all have similar physical and chemical properties and they all have one electron in their outer shell
What is the mass and charge of a proton?
A mass of 1 and a charge of +1
What is the mass and charge of an electron?
Almost zero mass and a charge of -1
What is the mass and charge of a neutron?
A mass of 1 and no charge (it’s neutral)
Describe the trends in melting point and reactivity as you go down Group 1.
Melting pint decreases and reactivity increases going down the group.
Give one reason why Group 1 elements are called ‘alkali metals’/
They react with water to produce alkaline hydroxide solutions.
Describe how potassium reacts with cold water.
It floats, fizzes and moves around the surface of the water. Hydrogen and potassium hydroxide are produced. The gas ignites to give a purple flame.
Why does potassium react faster than sodium? (HT)
Its outer electron is further from the nucleus, so it;s held less strongly and lost more easily.
Which of the following is the odd one out and why?
- Chlorine
- Lithium
- Iodine
- Bromine
- Fluorine
Lithium is the odd one out because the other elements are halogens.
What happens to the melting point and reactivity of the halogens as you go down the group?
The melting point increases and the reactivity decreases.
What will be the products when bromine is mixed with a solution of potassium iodide?
Potassium bromide and iodine
What is the name of the product made when lithium reacts with fluorine?
Lithium fluoride
What is meant by the term ‘hydrosphere’?
The hydrosphere is the term used for the water and dissolved salts on Earth.
What is the percentage of oxygen in dry air?
21%
State 2 properties of diamond.
Any two from: it has a high melting point, it’s hard, it’s insoluble in water
State 2 typical patterns of ionic compounds.
Any two from: they have a high melting point, they have a high boiling point, they don’t conduct when solid, they conduct when molten or if dissolved.
Describe how you would test for a metal ion in an aqueous solution.
Add sodium hydroxide solution and see the colour the precipitate is
Describe how you would test for the presence of sulfate ions.
Add barium nitrate solution. A white precipitate identifies sulfate ions.
What happens to the positive and negative ions in electrolysis?
The positive ions move towards the negative electrode where they gain electrons. The negative ions move towards the positive electrode where they lose electrons.
Name the products at the positive and negative electrodes in the electrolysis of aluminium oxide.
Positive electrode = oxygen
Negative electrode = aluminium
Write a balanced ionic equation to show the formation of iron (III) hydroxide, Fe(OH)[3], from iron (III) ions (Fe[3+]) and hydrogen ions (OH[-]). (HT)
Fe cubed + (aq) + 3OH - (aq) = Fe (OH)[3] (s)
Describe the hazard symbols for toxic and flammable.
Toxic = skull and crossbones Flammable = a flame
State the formulae of hydrochloric acid and sulfuric acid.
HCl is hydrochloric acid and H[2]SO[4] is sulfuric acid
What is the formula of sodium hydroxide?
NaOH
Write a balanced symbol equation to show the reaction of magnesium oxide and nitric acid. (HT)
MgO + 2HNO[3] = Mg(NO[3])[2] + H[2]O
What is the RFM of MgCO[3]?
84
If the theoretic yield is 80kg but the actual yield is 60kg, what is the percentage yield?
75%
Suggest three ways to purify a product.
Any 3 from: crystillisation, filtration, evaporation, drying in an oven or a desiccator
How could you measure the yield and purity of a product?
Using a titration
What mass of CO[2] will be produced when 200kg of CaCO[3] is heated?
The equation is CaCO[3] = CaO + CO[2] (HT)
88kg
Define the term ‘rate of reaction’.
The amount of product made up per unit time.
List 3 ways to measure the rate of a reaction.
By weighing the reaction mixture, measuring the volume of gas produced, observing the formation of a precipitate
Why would chemists want to speed up the rate of an industrial reaction?
To make the chemical more quickly, so that more profit could be made
Explain why increasing the concentration speeds up a reaction.
The reactant particles are closer together, so the collisions are more frequent.
Explain why powders react faster than lumps.
Powders have a larger surface area, so collisions are more frequent
State 3 key points about a catalyst.
Any three from: catalysts speed up the rate of reactions, catalysts aren’t used up or chemically changed, different reactions need different catalysts, catalysts lower the activation energy
What is the name of the alkane with the formula C[4]H[10]?
Butane
What is the functional group present in all alcohols?
-OH
List one use for ethanol and one for methanol.
Ethanol: solvent or fuel
Methanol: chemical feedstock e.g. in the manufacture of cosmetics.
Write a balanced symbol equation for the complete combustion of butanol. (HT)
Give 3 ways that ethanol could be produced.
Fermentation, synthesis and biotechnology
What happens to enzymes if they get too hot?
They become denatured and their shape changes permanently, so they can no longer work
What functional group is present in carboxylic acids?
-COOH
What sort of chemical do you think might be used as the flavouring in pear drops?
An ester
What type of reaction takes in energy from its surroundings?
Endothermic
Is making bonds endothermic or exothermic?
Exothermic
If a reaction takes in more energy to break the reactants’ bonds than it releases when the products are made, will it be endothermic or exothermic?
Endothermic
In the purification of an ester, why is sodium carbonate added to the separating funnel? (HT)
To remove any unreacted acid
What are the raw materials for the Haber process and where do they come from?
The nitrogen comes from the air. The hydrogen comes from natural gas.
Why are the unreacted gases leaving the Haber process reactor recycled?
To save money and increase the overall yield
Why is it important to test several samples when analysing a substance?
To ensure that the results are reliable and representative of the substance
In paper chromatography, what are the mobile and stationary phases?
Mobile phase is usually water. Stationary phase is paper
How is the R, value calculated?
R[f] value = distance travelled by substance / distance travelled by solvent
In gas chromatography, what is the ‘retention time’?
The time taken for a particular substance to pass through the GC column and be detected
When performing a titration, why is it important to collect more than one result?
To ensure that your results are reliable or consistent
How do you convert cm cubed to dm cubed?
Divide by 1000
Name 2 types of error.
Random error, systematic error
