Developing Metals Flashcards
Give 2 metals found in their pure state (not compounds)
Gold, Silver, Copper
What are pure, gold and silver like- physically?
Soft
How can these metals be made less soft?
Mixing with other metals to form alloys
What oxidation states can Iron have?
+2 and +3
What oxidation states can copper have?
+1 and +2
When filling up electronic shells, what fills up first 4s or 3d?
4s
What’s Chromium’s electronic configuration?
1s2 2s2 2p6 3s2 3p6 3d5 4s1(doesn’t obey usual rule as 4s isn’t fully filled before 3d)
What’s Copper’s electronic configuration?
1s2 2s2 2p6 3s2 3p6 3d10 4s1 (also doesn’t obey usual rule)
When d-block atoms form ions, where are the electrons lost from first?
4s sub-shell
Ions in the d-block have their outermost electrons in which sub-shell?
3d
Give 2 examples of transition metals as catalysts
Hydrogenation of alkenes is catalysed by nickel or platinum.
Manufacture of ammonia by Haber process is catalysed by iron
Manufacture of sulfuric acid is catalysed by vanadium (V) oxide
Alloys of platinum and Rhodium used in car’s catalytic converters
What are the two types of catalysts?
Heterogeneous and Homogeneous
What’s heterogeneous catalysis?
When the catalyst is in a different phase/state to the reactants.
What’s a Homogeneous catalyst?
A catalyst in the same phase/state to the reactants.
Give some examples of coloured glass uses (2)
- stained glass windows
- Worktops
- Doors
- Vases
- Glasses
- Bottles
When you see coloured glass, why is it visible as a colour?
The colour which has the frequency which passes through the glass, the rest are absorbed.
In pottery, why do you see the colour you do?
The colour seen has a wavelength which is reflected off the surface and the rest of the colours are absorbed
What wavelength region is visible light in?
400nm- 700nm
What colour has a 400nm wavelength?
Violet
What colour has a 700nm wavelength?
Red
If frequency is high, wavelength is?
short
What colour is Fe2+ in solution?
Green
What colour is Fe3+ in solution?
yellow (rust colored)
What colour is Cu2+ in solution?
Blue
What’s disproportionation?
In a reaction if a species is both reduced and oxidised, it’s said to be disproportionate
What’s required for light to be absorbed by an atom?
The energy of the light matches the energy gap between two energy states in the atom.
When violet is absorbed by a solution, what colour is the solution visible as?
Yellow
What’s a redox reaction?
A reaction where electrons are transferred- reduction and oxidation occur
How can you reduce a redox reaction into more simple parts?
An oxidation half equation and a reduction half equation
How would you write the full redox reaction for Acified manganate (VII) being reduced to Mn2+ by Fe2+ ions?
The half equation for the iron being oxidised is: Fe 2+ –> Fe 3+ + e-
However the manganate being reduced is harder to give a half equation: MnO4 - –> Mn 2+.
First balance the oxygens, by adding a water to the right side of the equation: MnO4 - –> Mn 2+ + 4H2O
Now balance the Hydrogens by adding H+ ions to the left side: MnO4 - + 8H+ –> Mn2+ +4H20
Then you need to balance the charges using electrons: MnO4 - + 8H+ + 5e- –> Mn2+ + 4H2O
Now you have to make sure the electrons produced in the iron half equation matches that gained in the Manganate (VII). (x all components of the Fe half equation by 5)
Final redox equation:
MnO4 - (aq) + 8H+ (aq) + 5Fe 2+ (aq) –> Mn2+ (aq) + 5Fe 3+ (aq) + 4 H2O. –long ting
How would you use a titration to work out how much acid is needed to neutralise a base?
-Measure out a known volume of alkali using a pipette, in to a flask
- Add some indicator
-Firstly, do a rough titration to get an idea of around where the end point is by adding acid and swirling the flask
- Then do an accurate titration by running the acid within 2cm3 of the end point found in the rough titration, then add it drop by drop and record the exact volume of acid required to neutralise the base
-Repeat a few times to get an accurate mean finding
(you can also do these titrations the other way round- adding base to acid)
What’s the purpose of redox titrations?
To find out how much oxidising agent is required to react exactly with a quantity of reducing agent- or vice versa.
What type of redox titration do we have to know?
Manganate (VII) ions (MnO4 -) as the oxidising agent
How would you do this manganate (VII) titration?
- measure out a quantity of reducing agent e.g. Fe 2+ ions using a pipette and put in a conical flask
-Then add some dilute sulfuric acid to the flask (in excess) this is for ensuring there’s H+ ions to allow the reduction of manganate - Now start adding the aqueous manganate to the flask using the burette, swirling the flask as you go.
-Stop when the colour just starts to change and record the volume of manganate used (this is a rough titration) - Then do more accurate ones to get 2 or more findings within 0.10cm3 of each other
(you can also do the titration with the reducing and oxidising agent in the other position (e.g. manganate in the flask)
How do you know when the manganate reaction is completed?
There’s a colour change from the colourless reducing agent to pink (because the manganate (VII) ions are purple)- the exact moment it goes baby pink is when the reaction is done (end point)
How would you use the titration results to find the concentration of the reagent (reducing agent)? - In the manganate (VII) titration
Work out how many moles of MnO 4- you added to the flask (conc x vol)= moles
Then look at the balanced equation for the reaction to find how many moles of reducing agent react with every mole of MnO 4- to work out the moles of reducing agent that were in the flask.
Then work out the moles that would be in 1dm3- this is the concentration
27.5cm3 of 0.0200 mol dm-3 of auqeous potassium manganate (VII) reacted with 25cm3 of acified iron (II) sulfate solution. calculate the concentration of Fe 2+ ions in the solution.
- Calculate moles of MnO 4- = 0.0275 x 0.0200= 5.5x10-4 moles
-Look at the balanced equation -
MnO4 - + 8H+ + 5Fe 2+ –> Mn 2+ + 4H2O +5Fe3+
so five moles of Fe2+ react with one mole of MnO4 -, therefore x moles by 5- 5.5x10-4 x 5 = 2.75 x 10-3 - Then work out the concentration by dividing moles by volume = 27.5x 10-3/ 0.025 =
0.110 mol dm-3
Name two pieces of equipment you can use to accurately measure the volume of a solution in a titration
- pipette
- burette
How to you determine when the end point of a titration has been reached?
When the colour change first occurs
Why don’t you need to add an indicator when doing a redox with manganate (VII) ions?
Because the manganate ions are coloured and the reagent is colourless, so you can see when a colour change occurs
What is meant by the term Coordination Number?
The number of dative covalent (coordinate) bonds formed between the central metal ion and the ligand.
If an ion has 6 ligands bonded to it coordinately, what shape and bond angle has it got?
Octahedral + 90o
If a metal ion has 4 coordinately bonded ligands what shapes and bond angles could it have
- Tetrahedral + 109.5o
- Square planar + 90o