redox I Flashcards
what are the rule that help to assign oxidation numbers?
1) all uncombined elements have an oxidation number of 0, element that are bonded to identical atoms will also be 0
2) the oxidation of a single monatomic ion will be the same as its charge
3) for molecular ions the sum of the oxidation numbers is the same as the overall charge of the ion. each of the constituent ions will have an oxidation number of their own
4) for a neutral compound the overall charge is 0
5) hydrogen always has a charge of 1+ except in metal hydrides and oxygen almost always has one f -2 except in peroxides
how can you use the oxidation number to write the chemical formulae?
you can assume that the overall charge on the compound is 0 and so to work out the chemical formula you’ve just got to work out the ratio of anions and cations that gives a charge of 0
what happens to the oxidation number when electrons are lost or gained?
the oxidation number will increase by 1 for every electron lost and decrease by 1 for every electron gained.
how do you tell if smoothing is oxidised or reduced?
you assign each element an oxidation nu,beri before the reaction and after the reaction. if the oxidation number has increased then the electrons have been lost and it has been oxidised and vice versa
how do you write half equations and then combine them into redox equations
ionic half equations show oxidation or reduction
you show the electrons that are being loss or gained in the half-equation. you then need to make the number of electrons in the equations equal and then add them together thus cancelling out the electrons.
hoe can you use e- H+ and H2O to balance half equations?
in an equation to balance any oxygens you need to to add water and then to balance the hydrogens in the water you need to add H+ and then you need to add electrons to balance out the charges. then you have to make the electrons equal and then add the two equations together
