What is normality?

[axp107]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

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[vicinihil]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

i believe it's like equivalence...

1M of HCL provides 1 mol of H+ so 1N
1M of H2SO4 provides 2 mol of H+ so 2N

 

[Cataract]

Just think of it as the number of moles of H+ or -OH that a compound contains per liter of solution. It's almost always used for acids and bases and that's the best way to think of it.

 

[proclivity]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

You're definitely not normal....none of us are. HAHAHAHAHHAHAHA

 

[vicinihil]

nice!

 

[majik1213]

go to google.com and type in "define:normality" without quotes.

 

[andexterouss]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

Actually, i think EK talked about it but in passing. Normality is basically number of equivalents. For example, 1M of HCL has only one proton/hydrogen ion, therefore, its normality is 1N.1M of H2SO4 has 2 hydrogen ions, therefore, its normality is 2N. Hope that helps.

 

[vicinihil]

we are def not normal...

apparently...physicians get paid an average of $62 an hour (140K/year) while optometrists are almost at $60....Dentists at $55 or so...who needs a pain in the gluteus schooling + residency + long work weeks...physicians...where's the normality in that?

 

[BerkReviewTeach]

we are def not normal...

apparently...physicians get paid an average of $62 an hour (140K/year) while optometrists are almost at $60....Dentists at $55 or so...who needs a pain in the gluteus schooling + residency + long work weeks...physicians...where's the normality in that?

That's the kind of thought that makes one want see if they are soluble in ethanol.

 

[axp107]

Ook thanks.. so the number of H+ ions it gives up..

so H2SO4 is 2 N..

but how many equivalents is that.. is it still 2 ... or is it 1/2

I remember seeing something where since it's 1 liter you divide by a half or something

 

[elektroshok]

Ook thanks.. so the number of H+ ions it gives up..

so H2SO4 is 2 N..

but how many equivalents is that.. is it still 2 ... or is it 1/2

I remember seeing something where since it's 1 liter you divide by a half or something

If you have one molar H2SO4, that is a 2 Normal solution
If you have .5 molar, then that is 1 Normal solution

 

[BrokenGlass]

You're definitely not normal....none of us are. HAHAHAHAHHAHAHA

This may sound like a distinction without a difference, but normality and normalcy are NOT the same thing.

 

[scgamer2000]

If you have one molar H2SO4, that is a 2 Normal solution
If you have .5 molar, then that is 1 Normal solution

Yeah, the best explanation of I think I've heard is from one of the Kaplan books that said that normalcy is "the molarity of the stuff you care about." So in the context of an acid-base reaction, a 1 M sulfuric acid solution is 2 N. But if you're interested in, say, common ion effect from having sulfuric acid and a sulfate salt in solution, the a 1 M acid solution is 1 N. (You're interested in the concentration of sulfate ion instead of the hydrogen.)

 

[axp107]

Just to completely understand it.. can someone explain this problem

A given volume of diprotic acid is completely neutralized by twice that volume of a 0.3 N NaOH solution. What is the molarity of the acid?

Answer: 0.3 M

 

[Spidey10]

Just to completely understand it.. can someone explain this problem

A given volume of diprotic acid is completely neutralized by twice that volume of a 0.3 N NaOH solution. What is the molarity of the acid?

Answer: 0.3 M

Well, if its a diprotic acid, then there are 2 equivalents of protons. If you then have 2 times the volume of base (each volume containing 1 equivalent), then one volume of base will neutralize 1 equivalent of protons, and the other volume will take the other equivalent of proton.

Remember, they are asking you what the molarity of the ACID is, not the concentration of protons (which would be 0.6 M). The acid molecule (eg. H2SO4) is only present in 0.3 M, and when it dissociates it produces 0.6 M of protons. Therefore it will need twice the volume of a 0.3 M OH- solution to completely neutralize the 0.6 M H+.

 

[scgamer2000]

Just to completely understand it.. can someone explain this problem

A given volume of diprotic acid is completely neutralized by twice that volume of a 0.3 N NaOH solution. What is the molarity of the acid?

Answer: 0.3 M

OK, so here's what happens. Pick an arbitrary volume of base if it makes it easier for you to understand, say 1 L.

1 L of 0.3 N NaOH will have 0.3 mol of OH- ions since this base has a single -OH group. You're told that 1/2 a liter of the diprotic acid is completely neutralized by this 1 L of base. Since the acid is diprotic, that means you get 2 H+ ions per mol of acid.

So, in 1/2 L of acid, you somehow need to get 0.3 mols of H+ ions. But to get 0.3 mols of H+ ions, you only need 0.15 mol of acid in the solution.

That means you have 0.15 mol / (1/2 L) = 0.3 M acid. However, the normality of the acid is in fact 0.6 N since it's a diprotic acid. If it was a tri-protic acid, you'd have a 0.9 N solution.

 

[BrokenGlass]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

Normality is staying away from this board.

 

[riceman04]

I see it every now and then on practice problems.. except Kaplan kinda briefly mentioned it..

and its not even talked about in EK

yuh huhhhhh they talk about it in EK AO