These notes offer a comprehensive guide to the theory needed to write final exams in matric. They contain all the information on Redox and Galvanic Cells in the IEB chemistry syllabus. They are typed in a column format for easy learning. They have an array of diagrams to aid learners in their physi...
Oxidation and Reduction
Chapter 17
Electrochemistry: refers 2 chemical Oxidation Numbers
reactions where converted from
Indicates if electrons move away /
chemical energy 2 electrical energy /
towards atom during bond formation.
electrical energy 2 chemical energy.
Pos moves away & neg moves towards.
Basics Rules
Redox reactions occur when electron 1. Pure element = 0
transfer takes place. 2. Hydrogen = +1 unless it is a
Represented by 2 half reactions & hydride of an alkaline metal (group
both must occur. 1&2) = -1
• An oxidation half reaction 3. Oxygen = -2 except when bonded 2
• A reduction half reaction fluorine = +1, if a peroxide = -1
• both halves are added 2 4. Group 1,2&3 = positive &
produce net redox reaction. correspond w/ group number
Oxidation 5. Zinc(Zn) = +2 & silver(Ag) = +1
6. Halides (neg ions of halogens) = -1
(OIL) unless bonded 2 oxygen = +1
Loss of electrons by a substance 7. Sum of oxidation numbers add up
(atom, molecule, ion). to 0
𝑋 → 𝑋+ + 𝑒− 8. Sum of compound ions add up to
Electrons = product. the charge of the ion
𝑌− → 𝑌 + 𝑒− Example
Substance that = oxidised (loses 𝑀𝑛𝑂4 − : find oxidation # of Mn.
electrons) = reducing agent (RA). 𝓍 + 4 −2 = −1
Oxidation # of substance oxidized 𝓍 = +7
increases (less neg/+ pos)
SAGS DEFINITIONS
Reduction
(RIG) Redox a reaction involving
reaction the transfer of
Gain of electrons (in atom, molecule, electrons
ion)
𝑋 + 𝑒− → 𝑋− Oxidation the loss of electrons
𝑌+ + 𝑒− → 𝑌
Reduction the gain of electrons
Electrons = reactant.
Substance = reduced is oxidising agent oxidising a substance that
(OA). agent accepts electrons
Oxidation # of substance that is
reduced decreases. reducing a substance that
agent donates electrons
, Electromotive Series
Electromotive series (reactivity series) = list of subs which are arranged in
order of ability 2 act as RA/OA.
The Table of Standard Reduction Potentials = an electromotive series.
Before table can be used, all ionic compounds & H2SO4, HNO3 as well as HCℓ
must be dissociated in2 ions.
Strong reducing
Oxidation half- agents = higher
reactions = read on table & are
from right 2 oxidised.
left.
Reduction half-
reactions = read
from left 2
right.
*Always use
single arrows.*
Strong oxidising
agents = lower
on table & are
reduced.
Substances on Substances on
left = reduced & right = oxidised &
are OA. are RA.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller amywallace. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.70. You're not tied to anything after your purchase.