Module 3 Lecture 1 Flashcards
How does a reaction with two neutral atoms as reactants produce an ionic compound as a product?
By having half equations within them that the neutral atoms react to cations or anions
What happens in redox equations?
The transfer of electrons
What must be added to half equations to balance the charge on each side?
electrons
What is oxidation?
A process in which chemical species loses and electron (or electrons)
What is reduction?
A process in which a chemical species gains an electron or electrons
What do we get when we add the two half equations together and balance it?
The overall reduction-oxidation (redox) equation
What needs to be cancelled out in the overall redox equation?
electrons and other species that are the same on both sides.
What is an oxidant (oxidising agent)?
A chemical substance which gains an electron/s in an electron transfer reaction.
It oxidises the other thing.
Is itself reduced.
What is a reductant (reducing agent)?
A chemical substance which loses an electron/s in an electron transfer reaction.
It reduces the other thing.
Is itself oxidised.
What is the oxidation number of atoms that exist as elements?
Zero
What is the oxidation number of a monotomic (one atom) ion?
The same as the charge on the ion.
What is the oxidation number of Hydrogen?
In compounds is +1
Except in metal hydrides which we don’t study.
What is the oxidation number of oxygen?
In compounds is -2
Except in Hydrogen peroxide (H2O2) where is is -1
What is the sum of the oxidation numbers of atoms in a molecule?
Zero
What is the sum of oxidation numbers of atoms in a polyatomic (ions containing more than one atom) ion?
Equal to the charge on the ion
If an element undergoes an increase in oxidation number what is happening to it?
It is being oxidised
If an element undergoes a decrease in oxidation number, what is happening to it?
It is being reduced.
If oxygen is O2 in a neutral molecule what does its oxidation number end up being?
-2 x 2 = -4
When balancing the overall equation, what is added to balance oxygen?
H2O
When balancing the overall equation, what is added to balance the hydrogens?
H+
If an elements oxidation number goes from +7 to +2 how many electrons must be added?
5
What must be initially done if the redox reaction is taking place in a basic conditions?
It must first be treated as though it is in acidic conditions, balanced.
What must be added with the H+ ions?
OH- ions must be added in the same amount there is H+ ions and to BOTH sides of the equation.
What must happen to the side of the equation that has H+ and OH- in it?
They add to give water, so change to H2O
What is the last step of balancing redox equations in basic conditions?
Cancel out the extra H20
What body system involves a series of redox reactions?
Metabolism
