F334 Steel Story

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Where are most metals found?
As compounds in the Earth's crust. The ores are mined and the metal extracted by reduction. Unreactive metals (e.g. gold and silver) can be found as elements in earth's crust
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How are reactive metals (group 1 and 2 and aluminium) extracted?
Electrolysis
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How are less reactive metals (e.g. iron and zinc) extracted?
Reduction with carbon or carbon monoxide
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Describe 3 ways to prevent corrosion
Barrier protection (i.e. painting, greasing) to prevent O2/H2O coming into contact with iron/steel. Galvanising (covering in a thin layer of protective zinc that oxidises). Sacrificial protection (attaching blocks of more reactive metal).
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Is the 3d sub-shell or 4s sub-shell filled first?
4s because it has slightly lower energy
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What is a transition metal?
A d-block element that forms at least one ion with a partially filled sub-shell of d electrons
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When d-block elements react to form ions, what electrons are the first to be lost?
the 4s electrons
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In comparison with s-block metals, what physical properties do d-block metals have?
Good conductor of heat and electricity; denser; higher melting/boiling points; hard; durable; high tensile strength; good mechanical properties
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What four important chemical properties do transition metals have?
Variable oxidation states; formation of coloured ions; formation of complexes; catalytic activity3
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What colour are Cu2+ ions?
Blue
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What colour are Fe2+ ions?
Green
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What colour are Fe3+ ions?
Yellow/orange
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Why are transition metals able to form complexes?
Because their 3d orbitals can accommodate the electrons donated by the ligands
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Transition metals can act as both heterogeneous and homogeneous catalysts. Why can they act as homogeneous catalysts?
Able to change from one oxidation state to another during the reaction, before returning to original oxidation state
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What's a complex?
A central metal atom/ion surrounded by ligands
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What are ligands?
Molecules or anions with one or more lone pairs of electrons
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What types of bonds form between the ligand and central metal ion?
Dative covalent
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What is the coordination number?
The number of bonds between the central metal and the ligands
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What does monodentate, bidentate and polydentate mean?
Ligands can form one bond to central metal; can form 2 bonds; can form many bonds
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When does ligand substitution occur?
If the new complex is more stable than the previous one
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If conc. HCl is added to copper sulfate solution, what happens?
Colour changes from blue to yellow as chloride ligands replace the water ligands
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What is the equation and appearance of the product of the reaction between iron(II) ions and NaOH solution?
Fe2+ (aq) + 2OH- (aq) --> Fe(OH)2 (s) - Green gelatinous solid
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What is the equation and appearance of the product of the reaction between iron(III) ions and NaOH solution?
Fe3+ (aq) + 3OH- (aq) --> Fe(OH)3 (s) - Orange gelatinous solid
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What is the equation and appearance of the product of the reaction between copper(II) ions and NaOH solution?
Cu2+ (aq) + 2OH- (aq) --> Cu(OH)2 (s) - Pale blue solid
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What is the equation and appearance of the product of the reaction between copper(II) ions and excess ammonia solution?
[Cu(H2O)6]2+ (aq) + 4NH3 (aq) --> [Cu(NH3)4(H2O)2]2+ (aq) + 4H2O (l) - deep blue solution
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What does K stab stand for?
Stability constant
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Potassium manganate (VII) solution can be used in what kind of titration and why?
Redox titration because it's a strong oxidising agent. Can be used to find concentration of solutions containing iron (II) ions or hydrogen peroxide
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Why is no indicator required for that titration?
The potassium manganate (VII) has a purple colour that disappears as it reacts
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What's the equation for the reaction?
5Fe2+ (aq) + MnO4- (aq) + 8H+ (aq) --> 5Fe3+ (aq) + Mn2+ (aq) +4H2O (l)
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What are iodine-thiosulfate titrations used for?
To find the concentration of solutions of oxidising agents
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How is this titration carried out?
Known amount of oxidising agent reacts with excess acidified potassium iodide solution. Iodine produced titrated against standard solution of sodium thiosulfate. Starch added near end point.
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What is the equation for the reaction?
2S2O3 2- (aq) + I2 (aq) --> S4O6 2- (aq) + 2I- (aq)
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What happens when a metal is placed in an aqueous solution of its ions?
An equilibrium is established. A potential difference/electrode potential is created between the metal and solution of ions
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What properties/conditions can alter the electrode potential?
If a metal has a greater tendency to release electrons and form ions, it has a more negative one. Altering the temp or conc also alters it.
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What is it called when 2 half cells are connected?
An electrochemical cell
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What is the potential difference between the 2 half cells called?
Cell potential or e.m.f., E cell
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What is a salt bridge usually made from?
A strip of filter paper soaked in a saturated solution of potassium nitrate
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What is the reference electrode against which all other electrode potentials are measured
The standard hydrogen half cell. Its electrode potential under standard conditions is defined as 0.00V
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What is the equation of the half-reaction occurring in the standard hydrogen half-cell?
H+ (aq) + e- --> 1/2 H2 (g)
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How is the standard electrode potential of a half-cell defined?
The potential difference between it and a standard hydrogen half-cell
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How are half reactions always written?
As reduction processes (with oxidised species and electrons on the left hand side)
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What is used if the molecules and ions or ions are both in solution?
An inert electrode such as platinum
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What are the 2 half-reactions involved in the initial stage of of rusting (an electrochemical process)?
Fe2+ (aq) + 2e- --> Fe(s) and O2 (g) + 2H2O (l) + 4e- --> 4OH- (aq)
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What are the two secondary reactions in which rust forms?
Fe2+ (aq) + 2OH- (aq) --> Fe(OH)2 (s) and Fe(OH)2 (s) + O2 (aq) --> Fe2O3.xH2O (s)
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What happens at the edges of a water droplet? And away from the edges?
Oxygen concentrations are higher and oxygen reduced to hydroxide ions. Away from the edges, iron atoms are oxidised to iron (II) ions
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Why recycle steel?
Saves resources and energy, helps to reduce waste. Magnetic so easily separated from other waste. Except for aerosols, steel used for packaging easily recycled. Scrap steel important in BOS process
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If an object appears a certain colour, what colour would it have absorbed?
The complementary colour (so if it appears blue, it absorbed orange)
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What happens when visible light falls on a coloured substance?
Electrons move to higher energy levels and molecules become excited. Electrons fall back to intermediate energy levels. Energy re-emitted in various forms, including vibrational energy.
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Card 2

Front

How are reactive metals (group 1 and 2 and aluminium) extracted?

Back

Electrolysis

Card 3

Front

How are less reactive metals (e.g. iron and zinc) extracted?

Back

Preview of the front of card 3

Card 4

Front

Describe 3 ways to prevent corrosion

Back

Preview of the front of card 4

Card 5

Front

Is the 3d sub-shell or 4s sub-shell filled first?

Back

Preview of the front of card 5
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