Steel Story

Question 1

Extracting and purifying metals: where they found and how they extracted

Answer 1

Found as compounds in earths crust

Extracted by reduction method depends on reactivity of the metal

Question 2

How are reactive metals extracted

Answer 2

Eg of reactive ie group 1&2 &aluminum extracted by electrolysis

Question 3

Less reactive metals obtained from their ores by

Answer 3

Eg iron and zinc

And reduction with carbon and carbon monoxide

Question 4

Unreactive metals how they extracted?

Answer 4

Eg gold and silver

Found as elements in the earths crust

Question 5

3 ways to prevent corrosion against metal

Answer 5

Barrier protection- prevents oxygen coming into contact with iron/steel. Eg: painting, greasing, oiling and using polymer coatings
Galvanizing- steel can pin be covered in thin layer of protective zinc that oxidizes. Stainless steel contains chromium that oxidizes, leaving protective oxide layer.
Sacrificial protection: attaching blocks of more reactive metal (ie zinc) to large iron structures (ships) electrochemical cell is formed and the reactive metal corrodes preferentially.

Question 6

Where are transition metals found in periodic table

Answer 6

D block

Question 7

transition metal definition

Answer 7

D-block element that forms at least one ion with a partially filled sub-shell of d electrons.

Question 8

D-block elements react to form ions what are first to be lost

Answer 8

4S electrons

Question 9

Two exceptions to transition metals and why (elements)

Answer 9

Scandium - Sc3+ = 3d0
Zinc - Zn2+ = 3d10

Ions form empty or full d orbitals

Question 10

D - block metals physical properties

Answer 10

Good conductors of heat and electricity
Denser than S and have higher melting and boiling points
Hard and durable with high tensile strength and good mechanical properties

Question 11

Transition metals chemical properties: (4)

Answer 11

Variable oxi states
Formation of colored ions
Formation of complexes
Catalytic activity

Question 12

Variable oxidation states for transition metals- why and how

Answer 12

Because succession ionization enthalpies in 3D and 4S sub-shells are so small , so multiple electron loss is possible. In lower oxidation states - simple ions
In higher oxi states - they’re covalently bonded to electronegative element ie O and F forming anions

Question 13

Redox reaction transition metals and oxi states. Oxidisng agent or reducing agents

Answer 13

High oxi state - oxidizing agents

Low oxi state - reducing agents

Question 14

Formation of colored ions transition metals

Cu2+ Fe2+ and Fe3+ colors

Answer 14

Electron transitions occur within 3d sub-she’ll when vi visible light is absorbed. - only for ions with partially full d shells
Cu2+ (Aq) blue
Fe2+ (Aq) green
Fe3+ (Aq) yellow/orange

Question 15

Transition metals as catalyst

Answer 15

Heterogenous- provide surface for gaseous reactant to be adsorbed onto. Weak interactions between 3d and 4s electrons of transition metal keeps the molecules in place.

Homogenous - they’re able to change from one oxidation state to another during the reaction before turning back to their original

Question 16

Ligand definition

Answer 16

Molecules or anions with one or more lone pairs of electron

Question 17

In a complex…

Answer 17

A central metal ion is surrounded by Ligands

Question 18

What type of bonds to Ligands form with the metal

Answer 18

Dative covalent

Question 19

Number of bonds between central metal and Ligands is called

Answer 19

Coordination number

Question 20

Complex with overall charge

Answer 20

Complex ion, add square brackets and charge outside bracket

Question 21

Shapes of complexes coordination numbers 6 4 &2

Answer 21

6 octahedral
4 tetrahedral can be square planar
2 linear

Question 22

Single edta4- can form _______complex by _______ this is known as ______

Answer 22

Hexadentate
By wrapping itself round central metal atom
Known as chelation

Question 23

Types of Ligands
One bond to central
2 bonds to central
Many bonds to central

Answer 23

1- monodentate
2- bidentate
Many - poly dentists

Question 24

Naming complexes

Answer 24

Write the number of each type of ligand using, mono, di, tri, tetra, penta, hexa
Writhe the name of each ligand in alphabetical order
Write the name of central metal - English name if + or neutral and latinised name if negative
Write oxidation number of central metal in brackets

Question 25

Latinised names of metals

Answer 25

Cu cuprate
V vanadate 
Ti titanate 
Ag argentate 
Zn zincate 
Pb plumbate
Cr chromate

Question 26

Color in complexes

Answer 26

Lights falls on a complex some is absorbed some reflected/ transmitted.
Visible light is absorbed complex appears colored.
Presence of Ligands causes 5 d orbitals of central metal to split. Some become slightly higher in energy some lower. The small gap between these allows visible light to be absorbed. The colour of the complex we see is the complementary colour to what’s absorbed.

Question 27

Ligand substitution reactions

Answer 27

Also known as Ligand exchange reactions

One ligand displaces another. Occurs if new complex formed is more stable than the previous complex.

Question 28

Precip reactions with cu2+ fe2+ and fe3+

Answer 28

With sodium hydroxide
Fe2+ = green gelatinous solid
Fe3+ = orange gelatinous solid
Cu2+ = light blue solid

Question 29

Ammonia solution added to a solution containing copper (II) ions

Answer 29

Dark blue/violet solution forms

Ligand substitution example

Question 30

Larger the Kstab

Answer 30

Stability constant the more stable a complex is

Question 31

Potassium manganite (VII) titration

Answer 31

Pm = strong oxidizing agent used for solutions containing iron(II) or hydrogen peroxide.
Method-
Use Pipette to add a known volume of test solution into conical flask
Acidity this solution with dilute sulfuric acid
Add form burette pm and swirl till pale pink persists
Repeat titration till you have two titles within 0.1cm3 of each other

Question 32

Iodine- thiosulfate titration a

Answer 32

Used to find concentrations of oxidizing agents.
Known amount of oxidisng agent reacts with an excess of acidified potassium iodide solution. Iodine produced is then titration against a standard solution of sodium thiosulfate. Near end point few drops of starch solution is added giving intense blue/black colour, this disappears at the end point.

Question 33

Electrode potentials why and what

Answer 33

Metal is places in Aq solutions of its ions equilibrium is established. An electrode potential is created between the metal and the solution of ions.

Question 34

More negative electrode means

Answer 34

Greater the tendency that the metal will release electrons and for ions. Altering temp or concentration of ions in solution alters the value of electrode potential

Question 35

Two half cells connected together =

Answer 35

Electrochemical cell

Question 36

Potential difference between two half cells =

Answer 36

Cell potential or e.m.f

Ecell

Question 37

In a half cell which has negative terminal

Answer 37

One with more negative electrode potenatial

Question 38

Electrons flow from

Answer 38

Negative terminal to positive terminal

Question 39

Standard electrode potentials

Answer 39

Standard hydrogen half-cell, it’s electrode potential under standard conditions 0.00V

Question 40

Half cell containing molecules and ion or ions an

Answer 40

Platinum electrode is used (inert electrode)

Question 41

Standard conditions for standard electrode potentials

Answer 41

Temp 298 K
Pressure 1 ATM
conc 1mol/dm^3

Question 42

E cell =

Answer 42

Most positive electrode - most negative elecrtrode

Question 43

Predicting direction of a reaction

Answer 43

Remember half cell more negative electrode potential supplies electrons to half cell with more positive.

1. Look up half reactions and standard electrode potentials
2. Identify which half reaction has the more negative electrode, rewrite this showing it supplying electrons.
3. Balance number of electrons and add them together

Question 44

Rusting description

Answer 44

At the edges of water droplet, oxygen concentrations are higher, and oxygen is reduced to hydroxide ions. Away from edges iron atoms are oxidized to iron(II) Ions.

Question 45

Two half reactions involved in initial stages of rusting are

Answer 45

Fe2+ (aq) + 2e- --> Fe(s) 
O2(g) + 2H2O (l) + 4e- --> 4OH- (aq) 
Rust forms in series of secondary reactions 
1. Fe2 + 2OH- --> Fe(OH)2 (s)
2. Fe(OH)2 (s) --O2--> Fe2O3.xH2O(s)

Question 46

Why recycle steel?

Answer 46

Saves resources and energy& helps to reduce waste. Is magnetic so can be easily separated from other waste. Except for aerosols all steel used for packaging is easily recycled. Scrap steel is important in the BOS process- it’s added to the converter before the molten iron is poured in to help reduce ‘thermal shock’

Question 47

Why does an object appear colored?

Answer 47

Visible light falls on an object some wavelengths are absorbed and some reflected/transmitted. We see reflected/transmitted wavelengths. If all visible light is transmitted it will appear colourless.

Question 48

Electronic transitions - reasons for colour

Answer 48

When visible light falls on a colored substance the absorbed light is in the energy range that causes electronic transitions , electrons move to higher energy levels and the molecules become excited. Molecules. Don’t remain excited for long, as electrons fall back down intimidate energy levels the energy is re-emitted in various forms, including vibrational energy , many diffferent vibrational energy level within each electronic energy level.

Question 49

Colorimetry what and why it’s used

Answer 49

Experimental technique used to find concentration is a colored solution. The amount of energy absorbed by a solution - its absorbance- its proportional to the conc of the solution