oxidation and reduction Flashcards
define oxidation in terms of oxidation number
oxidation number increases
define reduction in terms of oxidation number
oxidation number decreases
define oxidation in terms of electrons
loss of electrons
define reduction in terms of electrons
gain of electrons
what is an oxidising agent
a substance that brings about oxidation in other substances. the oxidising agent itself is reduced
what is a reducing reagent
a substance that brings about reduction in other substances. the reducing agent itself is oxidised
what are examples of oxidising agents
hydrogen peroxide
potassium permanganate
sodium hypochlorite in bleach
what are examples of reducing agents
sulphur dioxide
carbon monoxide
define oxidation number
the charge that an atom has or appears to have when electrons are distributed according to certain rules
how do electronegativity values help us to identify oxidation number
the more electronegative element will always have a negative ON
what is the oxidation number of any uncombines element eg H2 or O2
0
what is the ON of an ion
the same as its charge
how do we calculate the ON of a compound?
the ONs of the separate elements must equal 0 when added together
what is oxygens ON
-2
when is oxygens ON not -2
in peroxides ie H2O2 - (ON= -1)
in OF2 - (ON= +2)
what is the ON of halogens
-1
when is the ON of halogens not -1
if they are bonded to a more electronegative element
how do you identify the oxidising/reducing agent
when an element is reduced the oxidation number decreases
when an element is oxidised the ON is increased
the reducing agent itself is oxidised
the oxidising agent itself is reduced
ie the element that is reduced is the oxidising agent and visa versa
how do you balance a redox equation.
assign oxidation numbers to every single element
identify which element change in oxidation number
write the half equations to explain what is happening in step 2
balance the half equations
recombine the half equations into the main equation
balance the rest of the equation
how to identify a redox equation
if there are ions in the equation.
