Developing metals

Question 1

what does a reducing agent do?

Answer 1

gives electrons to reduce something. oxidizes itself

Question 2

what does an oxidizing agent do?

Answer 2

takes electrons away from something to oxidase something, getting reduced itself.

Question 3

how do you do an acid-base titration?

Answer 3

1. rinse out burette with water and then acid solution
2. rinse out pipette with water and then base
3. pipette base out of bottle into flask and then top up to 250cm3
4. add indicator
5. do titres

Question 4

how do you do redox titrations?

Answer 4

1. first you measure out a reducing agent and then into a flask
2. add some dilute sulphuric acid
3. add oxidising agent to reducing agent using burrette
4. stop when solution is the colour of the oxidising agent or the colour of the indicator.

Question 5

what happens at the anode or cathode?

Answer 5

anode= the +ve electrode does oxidation
cathode= the -ve electrode does reduction

Question 6

how do you set up an electrochemical half cell?

Answer 6

1. clean metal you are using
2. clean any grease using propanone
3. place metal in beaker with ions of that metal
4. make a salt bridge by soaking filter paper in KCl
5. connect the electrodes to a voltmeter

Question 7

what is an electrode potential?

what do the forward and backward reactions indicate?

Answer 7

a potential between the positive and negative electrodes. makes a charge difference.
backwards reaction = oxidized and more -ve
forwards reaction= reduced and more +ve

Question 8

what is the standard electrode potential?

what are the standard conditions?

Answer 8

the voltage measured under standard conditions when the half-cell is connected to a standard hydrogen electrode.
standard condtions= 1 moldm03, 298K, 100kPa

Question 9

how can you calculate the E-cell?

Answer 9

more positive potential - more negative potential

Question 10

how can an electrochemical series tell you reactivity?

Answer 10

the more -ve EP has a more stable reactant side as the product has been oxidised. will stay as the ion.

the more +ve EP has a more stable product as the reactant has been reduced. will stay as the solid.

Question 11

what happens in rusting?

Answer 11

1. water + oxygen + iron (s) –> Fe(II) (aq) + 4OH^-
2. Fe(II) and hydroxide ions produce a precipiate of iron (ii) hydroxide
3. the Fe(OH)2 is oxidized further to Fe(OH)3 by oxygen
4. iron(III) hydroxide gradually turns to hydrated(III) oxide or Fe2O3. xH2O

Question 12

how can you prevent rusting?

Answer 12

painting with a polymer so less air mnakes contact
oiling or greasing so less air makes contact
sacrificial metal thats more reactive so has a more -ve EP

Question 13

what is a transition metal?

Answer 13

a d-block element that can form 1 stable ion with an incomplete d-sub shell

Question 14

whats the electron configuration of a transition metal like?

Answer 14

the d block has 10 sub-shells. to be a transition metal the ion must have 1 to 9 electrons.

Question 15

why aren’t Sc and Zn transition metals?

Answer 15

Sc only forms 1 ion which has an empty d sub-shell

Zn only forms 1 ion which has a full d sub-shell

Question 16

what are the common oxidation states of copper and iron? what are their colours?

Answer 16

Fe= +2 (green) and +3 (yellow)
Cu= +1 (red) and +2 (blue)

Question 17

what is a complex ion?

Answer 17

a central metal ion or atom surrounded by dative covalently bonded ligands.

Question 18

what is a dative covalent bond?

Answer 18

a bond where both electrons come from the sae atom (ligands)

Question 19

what is a ligand?

Answer 19

an atom or ion that donates a pair of electrons to a central transition metal ion to from a coordinate bond.

Question 20

what re ligands with one lone pair called?

Answer 20

monodentate and include water, ammonia, chloride ion and cyanide ion

Question 21

what ethandioate an example of?

Answer 21

a bidentate ion, can coordinately bond 2 times with a metal ion

Question 22

what is the coordinate number?

Answer 22

the number of coordinate bonds made

Question 23

what is the octahedral shape?

Answer 23

6 coordinate bonds
90 degrees
e.g. hexaaqueiorn (II), hexaaquairon (III) and hexaaquacopper (II)

Question 24

what is the tetrahedral shape?

Answer 24

4 coordinate bonds
bond angles are 109.5 degrees
e.g. tetrachlorocopper (2-), and tetraaminecopper (II)

Question 25

what is the square planer shape?

Answer 25

cisplatin
4 coordinate bonds
square planar shape
bond angles 90 degrees

Question 26

how do ligands split the 3d sub-shell up into 2 energy levels?

Answer 26

normally the 3d sub-shell has the same energy levels but when ligands binds the energy is passed onto the orbitals. this splits the sub-shell up. electrons tend to occupy the lower orbitals and to jump up to the higher energy level they =need to corresponding energy. this comes from visible light.
the amount of energy needs depends on the metal ion and its oxidation state, the ligands and coordination number as these affect the size of the energy gap and therefore the frequency of light needed to overcome.

Question 27

how are transition metals colored?

Answer 27

when visible light hits a transition metal, some frequencies are absorbed and some are reflected. these frequencies combine to make the complementary colour.

Question 28

what is the general rule for copper (II) hydroxides and ammonia? what are their colours?

Answer 28

[Cu(H2O)6] (II) + 2OH- –> [Cu(OH)2(H2O)4] + water

[Cu(H2O)6] (II) + 2NH3 –> [Cu(OH)2(H2O)4] + 2NH4+

both go from pale to dark blue

Question 29

what is the general rule for iron (II) and hydroxides or ammonia?

Answer 29

[Fe(H2O)6] (II) + 2OH- –> [Fe(OH)2(H2O)4] + water

[Fe(H2O)6] (II) + 2NH3 –> [Fe(OH)2(H2O)4] + 2NH4+

both goes from pale to dark green

Question 30

what is the general rule for iron (III) with hydroxides and ammonia? what is their colour?

Answer 30

[Fe(H2O)6] (II) + 3OH- –> [Fe(OH)3(H2O)3] + water

[Fe(H2O)6] (II) + 3NH3 –> [Fe(OH)3(H2O)3] + 3NH4+

both yellow to orange

Question 31

why are TM good catalysts?

Answer 31

because they change oxidation states very easily.