Clarification on moles and acid Concentration N

[grainsofgold]

I must have fallen asleeep when my chemistry prof went over this and yrs later I would like to know-


Can someone in layman's terms please explain to me how to use and understand Moles and how it would be used in what we do?

...and can also explain the definiton of N as it is used to express concentrations of acids?



Thanks in advance-



Art

 

[lazersteve]

Here's an example I have previously posted:

M vs N

Generally the easiest way to understand it is this:

M = Molarity = Moles of compound per liter

N = Normality (for acids) =number of H+ per mole of acid

A few examples:

Example A:

A 1 M solution of HCl contains 1 Mole of HCl ( ~36.5g ) per liter of solution.

The same solution is 1 N because there is one mole of H+ in one liter of HCl solution.

Example B:

A 1 M solution of H2SO4 contains 1 Mole of H2SO4 ( ~98.1 g ) per liter of solution.

The same solution is 2 N because there are 2 moles of H+ in one liter of H2SO4 solution.

Example C:

A 1.5 M solution of H2SO4 contains 1.5 Mole of H2SO4 ( ~147.2 g ) per liter of solution.

The same solution is 3 N because there are 3 (1.5 * 2 =3) moles of H+ in the one liter solution.


The same relationships exist for any ionic compound in solution. Normality can be expressed for positive or negative ion concentrations:

Examples:

H+, OH-, Cl-, Na+, SO4-

Typically N is used most frequently with acid (H+) and base (OH-) solutions.

Maybe someone else can explain it in simpler terms, but this is how I understand it.

Steve

 

[grainsofgold]

Thanks Steve-

Lets say=

If a process reccomends that you reduce a nitic solution to a lesser N amount-

How would you first determine the amount of Nitric in the solution? Would you use a pipeete and tritate it with a chemical to neutralize the nitic in a given amount and simply do an equation to dtermine the amount of Mole or N in the solution so that you can then figure out how much you need to add extra to reduce the acid by?


I just want to get a better understanding of this-

Thank you for your help-

Art

 

[lazersteve]

If a process reccomends that you reduce a nitic solution to a lesser N amount-

How would you first determine the amount of Nitric in the solution? Would you use a pipeete and tritate it with a chemical to neutralize the nitic in a given amount and simply do an equation to dtermine the amount of Mole or N in the solution so that you can then figure out how much you need to add extra to reduce the aciid?

If you do not know the initial Molarity then you must use titration to be accurate.

If the Molarity of the original solution is already accurately known, then I would just do the math.


Steve

 

[Lou]

Excellent explanation Steve.



Grainsofgold,

Generally speaking, for what we are doing, concentration can be guessed, and it's not need to know it quantitatively (a term for exactly how much). If you have a process advising you to use certain concentrations, post it up and we'll review it and put it into layman's terms.


This following table should be helpful for all of us here.

Molarities for commonly encountered, concentrated mineral acids:

http://www.rmcgold.com/acid_molarlity.htm

 

[grainsofgold]

Thanks Lou-

That chart helps-

Art

 

[Palladium]

I added the chart to the forum book. :wink:

Thanks Lou.