9.1 Oxidation and reduction Flashcards
what is the current definition of oxidation?
loss of electrons
what is the current definition of reduction?
gain of electrons
what are the 2 old definitions of oxidation?
- addition of oxygen
- loss of hydrogen
what are the 2 old definitions of reduction?
- loss of oxygen
- gain of hydrogen
why are the old definitions insufficent?
not every compound that is oxidized adds or loses oxygen or hydrogen
what is the mnemonic for the definitions of oxidation and reduction?
OILRIG
oxidation is the loss of electrons
reduction is the gain of electrons
how is oxidation related to oxidation state?
oxidation causes a gain in oxidation state
How is reduction related to oxidation state?
reduction causes a reduction/ decrease in oxidation state
what is a redox reaction?
a reduction and oxidation reaction, as both occurs at the same time
what are the 5 steps of the Winkler method?
- saturate water with oxygen
- leave for 5 days
- add excess manganese (II) salt
- add potassium iodide
- titrate with sodium thiosulphate
how many moles of dissolved oxygen are found using the Winkler method?
1/4 moles of produced iodine or used thiosulphate
what is the conversion of ppm to SI units?
1 ppm = 1 mg/dm^3
what is the formula for the concentration of oxygen in ppm?
[O2} = mass of oxygen (g)/ volume of oxygen (cm3) x 10^6
what is the formula for BOD?
BOD = final [O2] - initial [O2]
what is the difference between oxidation and reduction?
oxidation is the loss of electrons and reduction is the gain of electrons
why does oxidation and reduction occur at the same time during a reaction?
if a substance is oxidized, it means that the other substance is reduced. therefore, they always occur at the same time
—- is an increase in oxidation state
oxidation
—- is a decrease in oxidation state
reduction
an —- is a substance that oxidizes another substance and itself undergoes reduction
oxidizing agent
a —- is a substance that reduced another substance and itself undergoes oxidation
reducing agent
the —- is the application of redox to measure the biological oxygen demand
winkler method
the amount of dissolved oxygen required to decompose organic material in water is called the —-
biological oxygen demand (BOD)
1 mole of produced iodine or used thiosulphate in the winkler method is equal to —-
4 times the moles of dissolved oxygen
the —- is a table outlining the order of how easily different elements undergo oxidation, which decreases down the list
reactivity series
