Redox Reactions Flashcards
oxidation state
value assigned to atom of compound, measures electron control or possession. The apparent chage that an atom has in a molecule or ion.
Fluorine Oxidation State
-1
Chlorine Oxidation State
-1
Hydrogen Oxidation State
+1
Oxygen Oxidation State
-2
Exceptions to O, H, Cl, F oxidation states
when F, Cl, H, O are bonded to each other, the oxidation state stays the same
What is the oxidation number of an element on its own?
0
What is the oxidation number of a simple ion?
the charge of the ion
What is the sum of oxidation state of a compound?
0
What charge do metals have
positive
In reduction what happens for ionic and covalent bonds?
- ionic bond- negative ion
- covalent bond- atom has higher electron density around it
In oxidation what happens for ionic and covalent bonds?
- ionic bond- positive ion
- covalent bond- ion has lower electron density around it
What are the exceptions to F having an oxidative state of -1?
F is always -1
What are the exceptions of O have an oxidative state of -1?
- combining with H2, where it’s -1
- combining with F2, where it’s +2
Li, Na, K Oxidation State
+1
Mg, Ca Oxidation State
+2
oxidizing agent
reactant that accepts electrons to become reduced, bringing about oxidation of other reactant
reducing agent
reactant that supplies the electrons to become oxidized, bringing about reduction of other reactant
Where are the electrons in the equation for oxidation?
right side/ product side
Where are the electrons in the equations for reduction?
left side/ reactant side
Which metals are stronger reducing agents? And why?
reactive metals, they have the tendency to lose electrons and will push their electrons on to other substances to form positive ion
- displace other substance
What is the definition of an activity series?
to predict if a particular redox reaction between metal and ions of another metal will be feasible
What are the products of the electrolysis of Brine?
- hydrogen gas
- chlorine gas
- sodium hydroxide
What is 2 things hydrogen gas is used for?
- rocket fuel
- tracer isotope
What are two things chlorine gas is used for?
- disinfectant
- treat swimming pool water
What are 2 sodium hydroxide is used for?
- drain cleaner
- soaps/ detergent
What is a redox reaction?
a reaction where 1 substance is reduced and the other is oxidized
More reactive non-metals are stronger ______ agents.
stronger oxidizing agents, most readily reduced
Differences between acid/base titration and redox titration
- AC titr. = neutralization between acid and base
- RT= between oxidizing and reducing agent
- AC titr= protons transferred from acid to base
- RT= electrons transferred from reducing to oxidizing agent
State what is oxidized and reduced in analysis of iron with manganate (VII)
- oxidized- Fe2+ to Fe3+
- reduced- MnO4- to Mn2+
In analysis of iron with manganate (VII) what is the color change?
purple to colourless
What are redox titrations used for?
- pharmaceutical industry
- food and beverage industry
In iodine-thiosulfate reaction, what is the visible color change?
deep blue to colourless
In iodine-thiosulfate reaction, what is the indicator and when is it added
starch, and it is added during the titration
In iodine-thiosulfate reaction, what is the oxidizing and reducing agent?
- oxidizing: iodine
- reducing: thiosulfate ion
What is the BOD- biological oxygen demand?
- high BOD- low oxygen content in water
- low BOD- good oxygen content in water
What precautions do you take in the Winkler method?
- when pouring water, funnel should touch flask so no extra oxygen in added from air
What phosphates cause eutrophication and what does this do to oxygen?
- NO3- and PO43- cause algae blooms
decimating levels of O2
How is dissolved oxygen fixed during the winkler method?
- by adding Mn2+ compound
What compound is always added to the iodine in the winkler method, making it a titrations?
- iodine thiosulfate
What are the two types of electrochemical cells?
voltaic (galvanic) and electrolytic
How do voltaic cells generate electricity?
from spontaneous redox reactions which generate electricity`
How do electrolytic cells generate electricity?
non-spontaneous redox reactions: drive chemical reactions using electricity
What is a half cell?
a strip of metal in an electrolytic solution of its own ions
What is the oxidation number for copper?
Cu2+
What is the electrode potential?
the charge difference between the strip of metal and the solution of its own ions
Term used to describe electrodes when they don’t take part in redox reactions.
Inert
In an electrolytic cell, where does oxidation take place?
anode (+), where anions are oxidized
In an electrolytic cell, where does reduction take place?
cathode (-), where cations are reduced
What is an electrolytic cell?
Cell that produces a non-spontaneous redox reaction driven by outside electricity
What type of reaction is produced through an electrolytic cell?
endothermic reaction
What type of reaction is produced through a voltaic cell?
exothermic reaction
What is a voltaic/galvanic cell?
a spontaneous redox reaction that produces electricity
What two connections must a voltaic cell have?
- external electronic circuit
- salt bridge to complete the circuit
What does a salt bridge contain? Also, what does the salt bridge maintain?
an aqueous solution of ions
- maintains the potential difference
Without a salt bridge, what happens to the voltage?
no voltage is generated
How to test for hydrogen
squeaky pop
How to test for chlorine
damp blue litmus paper turns red then white
In all cells, electrons flow from ____ to _____.
In all cells, electrons flow from anode to cathode.
Write equation for iron with manganate (VII)
DO IT
Write 2 of the equations for the Iodine- thiosulfate reactions.
DO IT NOW
