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Chemical Reaction Balancing

I've been doing chemistry A-Level for awhile now but still have not been taught or learnt a good way to balance equations with alot of different products containing the same elements yet.

For example:
When concentrated sulfuric acid is added to potassium iodide, iodine is formed in
the following redox equations.
......KI + ......H2SO4 ......KHSO4 + ......l2 + S + ......H2O
8KI + 9H2SO4 8KHSO4 + 4l2 + H2S + 4H2O
(i) Balance the equation for the reaction that forms sulfur.

I don't get how to balance the equation quickly and easily to get the answer. (I know the answer already just am looking for a good way to approach similar questions).
Reply 1
leave oxygen atoms till last
hydrogens second last
then balance elements in turn.

so for the first example you gave;
1. balance the K
2. balance the iodine
3. balance the S
4. now do the H and finally the oxygen

thats the way I do it, not saying its the best way but it works for me
Original post by yomayos
I've been doing chemistry A-Level for awhile now but still have not been taught or learnt a good way to balance equations with alot of different products containing the same elements yet.

For example:
When concentrated sulfuric acid is added to potassium iodide, iodine is formed in
the following redox equations.
......KI + ......H2SO4 ......KHSO4 + ......l2 + S + ......H2O
8KI + 9H2SO4 8KHSO4 + 4l2 + H2S + 4H2O
(i) Balance the equation for the reaction that forms sulfur.

I don't get how to balance the equation quickly and easily to get the answer. (I know the answer already just am looking for a good way to approach similar questions).


This is a redox reaction. You need to consider oxidation of I- to I2 and reduction of sulfuric acid to S to balance this reaction. If you have not studied redox reactions better attempt this later.
Reply 3
Original post by scimus63
leave oxygen atoms till last
hydrogens second last
then balance elements in turn.

so for the first example you gave;
1. balance the K
2. balance the iodine
3. balance the S
4. now do the H and finally the oxygen

thats the way I do it, not saying its the best way but it works for me

The thing is with your method is that you balance the K's for example and then when you balance the I's you have to rebalance the K's and so on.
Reply 4
Original post by thomas.rhett
This is a redox reaction. You need to consider oxidation of I- to I2 and reduction of sulfuric acid to S to balance this reaction. If you have not studied redox reactions better attempt this later.

I have studied the whole course, this is just a small part which I wanted to find a better method of doing to save time and for ease.

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