Topic 5 - Separate Chemistry 1 Flashcards
What are the typical properties of transition metals?
Hard, strong and shiny Malleable Conductive High MP/BP High densities
What do transition metals make?
Good catalysts
What must you be able to recall that most metals are transition metals and that their
typical properties include?
High melting point
High density
The formation of coloured compounds
Catalytic activity of the metals and their compounds (exemplified by iron)
What are most transition metals visually wise?
Colourful
Name one industrial process that uses a transition metal catalyst and name the catalyst used?
Haber process and iron
Rubidium is a Group 1 metal
Palladium is a transition metal
Predict which of these two metals will have a higher densitiy
Palladium as it is a transition metal therefore its density will be larger than rubidium
Why are pure metals malleable?
Because they have a regular arrangement of identical ions that can slide over each other
What are alloys?
Metals made up of another element
What can alloys be made of?
Metal + Non-metal
or
Metal + Metal
How do alloys make stronger compounds?
Because different elements have different sized atoms therefore it will be much harder for the ions to slide over each other
Why is iron often alloyed?
To make it stronger and harder Prevent rust (corrosion)
Why is gold alloyed?
To make it stronger
What are aluminium alloys used in?
Aircraft manufacture
What is steel used for?
Bridges, cutlery, washing machines, pans, ships and tools
Explain why alloys of aluminium are used instead of pure aluminium for building aircraft?
Aluminium is not strong enough on its own for making aeroplanes therefore it is alloyed with small amounts of other metals to increase its strength
What type of a reaction is the rusting of iron?
A redox reaction
What must be in the presence for metals to corrode?
Oxygen and water
Why is rusting a redox reaction?
The metal loses electrons so it is oxidised whilst the oxygen gains electrons therefore the oxygen gets reduced
How do you test rusting?
Test with water but no oxygen, no water but oxygen and both]
rusting will only occur in last
When testing for rust how do you remove oxygen?
Oil
When testing for rust how do you remove water?
Add calcium chloride
How can you prevent rusting?
Painting
Oiling or greasing
Sacrifical protection
When is oil/grease used to prevent rusting?
When moving parts are involved
What is involved in galvanising?
A coat of zinc over iron
Why does galvanising work?
Because zinc is more reactive than iron, it’ll lose electrons and corrode in preference to iron
What is electroplating?
Coating the surface of a metal with another metal
How is electroplating done?
Using electrolysis
When electroplating, what is the cathode?
The object you’re going to electroplate
When electroplating, what is the anode?
The bar of metal you’re using for the plating
When electroplating, what is the electrolyte?
The solution containing the metal ions of the metal you’re plating
What type of metals are used for protection?
Unreactive and don’t corrode easily
When electroplating silver onto a brass cup?
Describe where everything is?
Cathode is the brass cup
Anode is a bar of pure silver
Electrolyte is silver solution
Outline how bolting some magnesium onto a piece of iron will prevent it from rusting?
Magnesium is more reactive than iron so will lose electrons/be oxidised/react with water and oxygen in preference to iron
What does titration allow you to find out?
Exactly how much acid is needed to neutralise a given quantity of alkali (vice versia)
When undergoing titration, why can’t you use universal indicator?
Because it changes colour gradually and you won’t get a single colour change
How do you undergo titration
Use a pipette to measure out a set volume of alkali into a flask
Add drops of an indicator
FIll a burette with a known conc/vol of acid
Slowly add acid until end point
Repeat without indicator
What is the formula for concentration (mol/dm^3)?
Concentration = Number of moles / Volume
How do you convert M into g/dm^3?
Times by the RF
What is the yield?
The amount of product you get from a reaction
What is the percentage yield equation?
Percentage Yield = Actual Yield / Theoretical Yield
Why don’t you always get a 100% yield?
Incomplete reactions - not all of the reactants have reacted
Practical losses - chemicals being lost between transfer of containers
Unwanted reactions - unexpected reactions happening
What does the atom economy tell you?
What percentage of the mass of reactants have been converted into your desired product
Whats the atom economy equation?
Atom Economy = Total Mr of desired products / Total Mr of all products
What does a 100% atom economy mean?
All of the atoms in the reactants have been turned into useful products
What do low atom economies do?
Use up resources very quickly and make alot of waste
When designing an industrial process, what must you consider?
The cost of extracting and refining the raw materials
Energy costs
Whether you can control the conditions or not
What is the haber process equation?
N2 + 3H2 ⇌ 2NH3 (+ heat)
In the haber process where does higher pressures favour?
The forward reaction as there are more moles on the left
What is the pressure for the haber process?
200 atmospheres
What ratio is hydrogen and nitrogen mixed in?
3:1
What temperature is best for the haber process equilibrium wise?
Low because the forward reaction is exothermic
Why isnt the haber process done in cold temperatures?
Because the cold temperatures althought means a higher yield the reaction rate will be much slower
What temperature is the haber process done at?
450*C
What catalyst is used in the haber process?
Iron catalyst
What doens’t the ccatalyst affect within the haber process?
The position of equilibrium or the % yield
A pressure of 200 atm is used in the production of ammonia
What would happen to the yield of ammonia if a higher pressure was used?
Explain your answer?
There would be more ammonia made as there is a higher number of moles on the left therefore more product will be made to balance that out
What do fertilisers often contain?
Nitrogen, phosphorus and potassium compounds
Whats the point of fertilisers?
To promote plant grow
What are the advantages of using ammonia for fertilisers?
You can control the compositions of chemicals in them
Soluble so can dissolve down into the soil to reach the plant
What is the advantage of using ammonium salts?
THEY ARE ALWAYS SOLUBLE
How do you make an ammonium salt?
Titration
Give the steps to make an ammonium salt?
Add a few drops of methyl orange indicator to the ammonia solution
Add the acid until the colour change
Repeat without indicator, then to get the ammonium crystals you can gently evaporate the solution (crystallise)
Why isn’t the titration method used in industry?
It’s extremely impractical for large quantities and using crystallisation is too slow
What is the definiton of molar volume?
The volume occupied by ONE MOLE OF A GAS
What are the units for molar volume?
dm^3/mol
What is the molar volume equation?
Molar volume = Gas volume / Number of moles
Whats the volume of 4.5 moles of chlorine at RTP?
4.5 x 24 = 108 dm^3
How many moles are there in 8280 cm^3 of hydrogen gas at RTP?
8280 / 1000 = 8.28
8.28 / 24 = 0.345 moles
The Mr of methane is 16
What volume will 36g of methane gas occupy at RTP?
Moles = Mass / Mr Moles = 36 / 16 Moles = 2.25
Volume = Moles x 24 Volume = 2.25 x 24 Volume = 54 dm^3
What do fuel cells use?
Fuel and oxygen
What do fuel cells do?
Produce electrical energy
When does a fuel cell stop?
When one of the reactants is used up
What is produced in a hydrogen-oxygen fuel cell?
Water
What is the equation for a hydrogen-oxygen fuel cell?
Hydrogen + Oxygen -> Water
2H2 + O2 -> 2H2O
What are the advantages of using hydrogen-oxygen fuel cells?
Fewer places to lose energy through heat
No moving parts so no loss of energy through friction
No production of greenhouse gases, nitrogen oxides, sulfur dioxide, carbon monoxide
What are the disadvantages of using hydrogen-oxygen fuel cells?
Since hydrogen is a gas, it is hard to store
Hydrogen is very explosive so it’s difficult to safely store
Hydrogen is made from hydrocarbons or by the electrolysis of water (both use electricity- which usually involves fossil fuels)
What are the properties of magnalium?
Lighter, stronger and less corrosive than aluminium
What does 18 carat gold actually mean?
18/24 = 75% pure gold
What element is added to iron to make steel?
Carbon
Give the two main reasons electroplating is done?
Improve the appearance of metals
Reduce corrosion
What does it mean when a reaction has a 100% percentage yield?
All of the predicted products have been made
Why aren’t reactions with low atom economies usually profitable?
Expensive to source materials and dispose of waste
Explain why the conditions used in the haber process are a compromise?
The haber process produces the most yield of ammonia at lower temperatures, however, the lower the temperature of ANY reaction the slower the products are produced, therefore a compromise is met for the most yield per time
