half equations Flashcards
look through notes to familiarise with the method
1
Q
what do we use half equations for ?
A
we use half equations to see more clearly what is happening in a reaction
- see the electrons transferred between the 2 substances
- show which substances are reduced and which are being oxidised
2
Q
what kind of reaction is this ?
Cu2+ + 2e- -> Cu
A
reduction as Cu is gaining 2 electrons to become neutral
3
Q
what kind of reaction is this ?
2Cl- -> Cl2 + 2e-
A
0xidation
because electrons have been lost
4
Q
what are the steps in writing half equations ?
A
1) write what you know as an equation
2)balance for atoms (not O or H)
3) balance for O by adding H2O
4) balance for H by adding H+ ions
5) balance charge by adding e-
5
Q
what do you do when you want to combine half equations ?
A
- write the redox reaction
- treat like a simultaneous equation with the electrons
- add everything on the right together and add everything on the left together
- get rid of any similarities on both sides
6
Q
what do chemical reactions only show ?
A
changes
