Chemistry - UNIT 4

metallurgy

the science that deals with procedures for extracting metal from ore

Reduction - old definition

substances that can react with metal compounds that can reduce it to its pure form

Oxidation - old definition

substances that reacts with metal to produce a metal compound

oxidation state

positive or negative number corresponding to the apparent charge that an atom in a molecule or ion would have if the electron pairs in covalent bonds belonged entirely to the more electronegative atom

redox

• during a chemical reaction, electrons get transferred between atoms

• this reaction can be shown through half reactions

oxidizing agent

the reactant that becomes reduced oxidizes the other reactant

• gains electrons

• ex. Mg2+, any cations, O2, F2, non-metals

reducing agent

the reactant that becomex oxidized reduced the other reactant

• loses electrons

• ex. Mg, anions, metals, F-, O2-

glavantic cells

galvanic cell (voltaic cell) makes up part of a battery

label the parts of galvanic cell

1. voltmeter

2. electrodes

3. electrolytes

4. salt bridge

5. cathode (+)

6. reduction

7. anode (-)

8. oxidation

cell notation → a | b || c | d

a & d: electrodes

b & c: electrolytes

each beaker of a galvanic cell is a

half cell

electrolyte

solution containing ions

electrodes

solids undergo redox reaction

cathode (+)

where reduction reaction occurs

anode (-)

where oxidation reaction occurs

salt bridge/u-tube

contains cations/anions

what is ΔE

energy difference between cathode and anode per unit of charge at standard conditions

• energy of electricity (voltage)

standard reduction potentional

the ability of a standard half-cell to compete for electrons

galvanic cells with inert electrodes

• when you have a redox reaction where a metal is not involved, you must use an inert electrode

• an inert electrode is an unreactive solid that connects ions in a solution involved in the redox reaction (ex. carbon - graphite, Pt)

ΔE is negative

non-spontaneous, galvanic cell will not work

ΔE is positive

spontaenous

what is the purpose of galvanic cells

to produce electricity

which cell needs a power source?

electrolytic cell

what are the 2 purposes electrolytic cells

1. seperatre ions in a solution

2. discharge ions (remove the charge

what is the sign of cathode in a electrolytic cell?

negative, reduction

what is the sign of anode in a electrolytic cell

positive, oxidation

what are the differences between an electrolytic cell and galvanic cell

• signs change

• electrolytic cell has no salt bridge

• galvanic cell has a voltmeter, electrolytic cell has a battery

• galvanic cell has 2 beakers, electrolytic cell has 1 beaker

faraday’s law

• mass of an element consumed or produced at an electrode is direct to the charge transfered

What did Michael Faraday investigate

the relationship between electricity and electro chemical charges

What does Q mean

quanitity of charge transformed by a current per second measured in Columbs

how to caclulate current

I = Q/t

What is faraday’s constant

96500

formula to calculate moles

ne = Q/F