How much potassium permanganate do you need to dissolve in 1Kg of water to have a concentration of 2%?

Answer 1

If you want 2% by weight then it would be 2% or 1Kg or 20 gm of potassium permanganate.

Answer 2

Per cent means per 100. But your question does not say 100 of what. In science we have to be sure what we mean.

If we assume it means per 100g of the solution, then let as assume we need x grams of permanganate. Then

x/(1000+x) = 2/100
or 100x = 2000+ 2x
98x = 2000
Therefore x= 2000/98
= 20.41 grams

Answer 3

a 2 % solution in water normally means 2g/100ml i.e. a w/v solution so for 1kg of water or 1L you would need 20g.

However, in the interests of being completely correct about this you should define it as a 2 % (w/v) solution.

Answer 4

I kg (1,000 grams) of water, by definition is 1 litre (1,000 ml) at sea level.

So in a litre of water, you put 0.02 x 1000 = 20 grams of dry weight chemical for a 2% solution

Answer 5

1 kg water = 1000 g
1000 x 0.02 (that is, 2%) = 20 g
So you need 20 g of KMnO4.
Note that this is indipendent of "what" you dissolve: 2% of 1 kg is always 20 g (of anything).