C14

Reactivity

The tendency for losing and gaining electrons to form a positive ion

Characteristics

quick/violent reactions, physical/observable change, can release/absorb energy

Metals

lose electrons

Know metal reactivity

unreactive metal for purpose

Displacement reaction

a more reactive metal will displace a less reactive one from a compound

Oxidation

when an element gains oxygen, loses electrons

Reduction

when an element loses oxygen, gains electrons

RED CAT

reduction, cations

AN OX

oxidation, anions

OIL RIG

only applies to electrons

OIL

oxidation is lose

RIG

reduction is gain

Oxidation states

elements on their own always equal 0

Oxidising agent

receives electrons

Reducing agent

donates electrons

Half equation

Shows either oxidation or reduction separately

Spectator ions

present but not involved in the actual chemical change

Electrolysis

use of electricity to break down a compound

Electrolytic cell

device where electrical energy causes a chemical reaction

Electrolyte

molten or aqueous substance that contains mobile ions

Ionic compound conducts electricity(solid)

the ions need to be mobile to conduct electricity

Cathode

negative ions are attracted (gain)

Anode

positive ions are attracted (lose)

Cathode reaction

reduction

Anode reaction

oxidation

Aqueous solution

substance dissolved in water

Cathode test

splinter pop test

Anode

splinter reignite

Cathode form

least reactive metal

Anode form

halogen > oxygen > other

Red UI

acid produced

Blue UI

has produced

Voltaic cell

converts chemical energy to electrical energy

Half cell

one part of a cell where either oxidation or reduction occurs

External circuit

path where electrons flow

Salt bridge

allows ions to move and maintain charge balance

Potential difference

Energy difference between two electrodes

Greater reactivity difference

higher voltage

Electrode

a piece of metal

anode

where oxidation occurs

cathode

where reduction occurs

Hydrogen fuel

hydrogen used as an energy source.

Electrolysis of water

splitting water using electricity: 2H2O → 2H2 + O2

Steam methane reforming (SMR)

producing hydrogen from methane: CH4 + H2O → CO + 3H2

Renewable energy

energy from sources that don’t run out.

Byproduct

extra substance produced in a reaction.

Advantages of hydrogen

clean (produces water), renewable (if using green energy)

Limitations

expensive, storage is difficult, energy intensive

Hydrogen fuel cell

device that generates electricity using hydrogen and oxygen.

Proton exchange membrane (PEM)

allows only H+ ions to pass through.

At anode (oxidation)

H2 → 2H+ + 2e

At cathode (reduction)

O2 + 4H+ + 4e

Efficiency

how much energy is converted usefully.

Zero emissions (point of use)

only water is produced during operation.

Challenges

storage, transport, cost, hydrogen production methods

oxidation observations

decrease in size

reduction observations

increase in size

Metals are immersed in

it’s ions

Lysis/lyte means to

breakdown

Redox anode

negative

Redox cathode

positive

Electrolysis anode

positive

Electrolysis cathode

negative

Break down using electricity

(electrolysis) decompose compounds

Uses electricity

(electrolytic) electrical to chemical energy

Movement of electrons

anode to cathode

Voltaic cell

converts chemical energy to electrical energy