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# Concentration question. watch

1. o.0

2. (Original post by blush.ox)
o.0

LOL! Answer it, if you can.
3. Oh, I thought it was another type of concentration...
4. (Original post by Comeheretellme)
Oh, I thought it was another type of concentration...
What kind of concentration are you going to find in a chemistry forum?
5. (Original post by Zishi)
fertilizer contains 15% N (15g in every 100g)

You use 14g fertilizer you use 14 x 15/100 g nitrogen

But you need moles of ATOMS = 14/14 x 15/100 = 0.15

You put this into 5 litres and the concentration is 0.15/5 = 0.03 mol dm-3
6. (Original post by Zishi)
Zishi: it has do somthing with the fact that Nitrogen is a gas ....and always occurs as N2 gas (a diatomic molecule). So when they say 15g on Nitrogen is there ..THEY MEAN 15g of N2 gas is there !!!!!!...so the Molecular weight of N2 is ~28g/mol....so that's why it is 3.5g/[28 g/mol].

Hope that helps!!!!!!!!!!
7. (Original post by Zishi)
What kind of concentration are you going to find in a chemistry forum?
I didn't realise it was in the chemistry forum
8. (Original post by CoolDude)
Zishi: it has do somthing with the fact that Nitrogen is a gas ....and always occurs as N2 gas (a diatomic molecule). So when they say 15g on Nitrogen is there ..THEY MEAN 15g of N2 gas is there !!!!!!...so the Molecular weight of N2 is ~28g/mol....so that's why it is 3.5g/[28 g/mol].

Hope that helps!!!!!!!!!!
It shouldn't.... it's wrong
9. (Original post by charco)
It shouldn't.... it's wrong
Oh Drat....I guess I screwed up!
10. (Original post by charco)
fertilizer contains 15% N (15g in every 100g)

You use 14g fertilizer you use 14 x 15/100 g nitrogen

But you need moles of ATOMS = 14/14 x 15/100 = 0.15

You put this into 5 litres and the concentration is 0.15/5 = 0.03 mol dm-3
But THAT is the ratio, so that isn't the actual mass of nitrogen in the fertilizer.
11. (Original post by Zishi)
But THAT is the ratio, so that isn't the actual mass of nitrogen in the fertilizer.

" ... the ratio per 100g of fertilizer"

If it were only N, P and K it would be a pretty horrendous mixture to put on plants...

N is a gas (Nitrogen) it would escape into the air
P is phosphorus it would burst into flames spontaneously and produce toxic acidic clouds of phosphorus pentoxide
K is potassium, which would burst into flames as it came into contact with any moisture in the soil...

You gonna stuff them together into a bag?
12. (Original post by charco)

&quot; ... the ratio per 100g of fertilizer&quot;

If it were only N, P and K it would be a pretty horrendous mixture to put on plants...

N is a gas (Nitrogen) it would escape into the air
P is phosphorus it would burst into flames spontaneously and produce toxic acidic clouds of phosphorus pentoxide
K is potassium, which would burst into flames as it came into contact with any moisture in the soil...

You gonna stuff them together into a bag?
LOL! So 'per' represents that they're present in exact quantities in 100g of Fertilizer as in the ratio, right?
13. (Original post by Zishi)
LOL! So 'per' represents that they're present in exact quantities in 100g of Fertilizer as in the ratio, right?
yes, 'per' means 'in'
14. (Original post by charco)
yes, 'per' means 'in'
Thank you very much!

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