Wrong Answers From PPs Flashcards
Three differences in physician properties between Group I metals and transition element?
Transition element is harder.
Transition element is stronger
Transition element has a high density
How is nitrogen obtained for the Haber Process?
It is brained by fractional distillation of liquid air
How can you define isomers (what do they share/not share)?
They have the same general formula and empirical formula but different structural formula.
What happens when an alkene is oxidised with acidified potassium manganate (VII)?
Goes from purple to colourless
Describe the structure and bonding in a metallic element?
It is a lattice structure of positive charges surrounded by a sea of delocalised electrons. There is attraction between positive and negative charges.
Define electrolysis
Breakdown of ionic compound when molten or in aqueous solution using electricity.
Test for chlorine?
Bleaches/turns colourless damp blue litmus paper
How is heat produced in zinc extraction?
By coke burning in air! (C+O2 —-> CO2)
What is a fuel? And an example of a solid one which is not a fossil fuel?
A substance burnt to produce energy/heat. Wood/biomass is an example
Characteristics of homologous series?
Same FUNCTIONAL group. Consecutive members differ by CH2. Physical properties vary in predictable manner. Common method of preparation. Same GENERAL formula. Similar chemical properties.
Methyl orange indicator in acid, neutral & alkali
In acid its red.
In neutral and alkaline its yellow.
Phenolphthalein indicator in acid, neutral and alkali?
Colourless in acid and neutral.
Pink in alkali.
How are carbon dioxide and carbon monoxide formed in motor vehicle engines?
Carbon dioxide formed by complete combustion of petrol
Carbon monoxide formed by incomplete combustion of petrol (2C + O2 —> 2CO)
Why is an alloy preferred to its original constituent metals?
It is harder/stronger.
It is more resistant to corrosion.
It has a better appearance.
Explain COMPLETELY the transfer of electrons in terms of a piece of steel exposed but coated with zinc?
The steel does not rust because zinc is more reactive than steel underneath so zinc loses electrons to oxygen and water instead of steel.
Zin forms IONS instead of steel.
What is a photochemical reaction?
A reaction whose rate is influenced by light
It occurs only in presence of light.
What are the two functions of coke in a blast furnace?
As a reducing agent.
Source of heat/energy.
What would the equations at anode and cathode be for the electrolysis of aluminium oxide?
Anode: 2O2- —> O2 + 4e-
Cathode: Al3+ + 3e- —-> Al
When you are side to describe things that would be observed in a reaction, which two main things should you think about?
That if it’s a solid then some of it will disappear/dissolve.
There will be a colour change.
Conditions for fermentation?
Yeast as a catalyst.
Anaerobic.
20-40 degrees C.
Aqueous solution.
Which raw material is the source of ethene?
Crude oil/petroleum
Physical properties of alkanes?
They are colourless and first four members are gases at room temperature and pressure. As the carbon chain gets longer, boiling points increase.
Properties of ionic compounds?
High melting and boiling points because of strong forces between ions.
Soluble in water but insoluble in other covalent compounds
Conduct electricity when molten only
Pattern of molecules in a solid vs in a gas
They have a fixed and REGULAR arrangement of molecules in solid and it is irregular and random in a gas
Describe decanting and centrifugation?
Decanting is pouring off the solution - suitable for solids and very heavy particles (e.g. Sand from water).
Centrifuge is a machine which spins test tubes round at high speeds and this pulls solid to bottom. Then you can decant liquid from solid.
Describe two things about equilibrium?
Rates of forward/backward are the same.
Concentrations do not change.
During fermentation, why does the rate increase initially and then why does it decrease?
Increases initially as temperature is higher/yeast multiply.
Then decreases glucose (reactant) it being used up AND concentration of ethanol is high enough to kill yeast.
Effects to environment of non-biodegradable plastics?
Landfills increase and use natural resources.
Ingestion can be fatal to animals.
Animals can get caught in plastics.
Exposure to air, light, water causes plastics to emit toxic pollutants.
Why is graphite soft and why is it a good conductor of electricity?
It is soft because of weak forces between layers - so layers slide over each other.
It conducts electricity as it has free electrons that can move between layers.
Structure of silicon dioxide? And properties that is has similar to diamond?
Every silicon atom is bonded to 4 oxygen atoms.
Diamond and Silicon IV oxide have high density, are hard, have high mp/bp, non conductor of electricity/heat.
Uses of graphic due to its softness and also conduction of electricity?
- Lubricants, pencils, polishes
- electrodes, brushes (in motor)
Uses of sulfur dioxide?
Sterilising, insecticide, bleaching/in manufacture of wood pulp, fruit juice, food
How is sulfur dioxide made from the ore zinc sulfide?
Roasting of ore zinc sulfide IN AIR
2ZnS + 3O2 —> 2ZnO + 2SO2
What is an advantage of lower temperature in a reaction (not including reversible reactions)?
To save energy
Why is sulfuric acid not reacted directly in water?
- reaction is too violent
- a fine mist of sulfuric acid forms
Why is carbon monoxide formed higher in Blast Furnace?
There is insufficient oxygen.
Carbon reacts with carbon dioxide.
(C + CO2 –> 2CO)
Why does molten iron not react with air? (In blast furnace)
There is no oxygen in contact with iron.
The layers of slag prevents hot iron reacting with oxygen.
Name at least 5 fossil fuels
Crude oil, natural gas, coal, refinery gas, gasoline
Why is combustion of wood more effective than coal in terms of reducing CO2 level in atmosphere?
- Wood combustion produces less CO2
- trees (wood) takes in CO2 by photosynthesis
- So overall wood is a carbon neutral fuel
Use of mild steel&high carbon steel and low alloy steels&stainless steel?
Mild steel - car bodies, machinery, building material
High carbon steel - hammers, drills, knives
Low alloy steel - bicycle chains, bridges
Stainless steel - pipes/towers @chemical factories, cutlery, surgical instruments
What is the use of paraffin, gasoline and lubricating oil?
- Paraffin: jet fuel
- Gasoline: fuel for cars
- Lubricating oil: Vaseline/waxes
In terms of electrons, what is an oxidant/oxidising agent and where would you find the best ion for an oxidant in the reactivity series?
An oxidising agent is an substance that causes the loss of electrons. Therefore a job lower down in reactivity series would be best because it is least reactive - gains electrons more easily.
Why can’t giant covalent structures conduct electricity?
They have no ions and they no free moving electrons.
Describe bonding in a typical metal.
Lattice of positive ions surrounded by a sea of delocalised electrons with attractive forces between positive ions&the electrons
How can you prepare a neutral solution of magnesium chloride?
Add Magnesium metal to hydrochloric acid.
Add until excess
Filter off
If a salt has indicator still in it, how can you obtain a neutral solution of a salt (e.g. Lithium chloride) w/o the indicator?
- Add carbon and then filter
2. Or do titration and repeat experiment without indicator using same quantity of acid.
