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Molarity

What is the molarity of 42 degree nitric acid?

Jacob Keith Taylor
- Madisonville, Kentucky
2002

42 degree baumé Nitric is approximately 15.8 Molar or Normal.

Ira Donovan, M.S.F.
Kansas City, Missouri
2002

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In my chemistry class, my teacher did explain how to find the molarity of a substance. However due to her lack of fluent English, I couldn't fully comprehend what she was saying. So, if I may kindly ask to you sir, how do you calculate the molarity of a substance?

Thank you very much.
Elizabeth

Elizabeth G.
grade 10 student - Queensland, Brisbane, Australia
February 23, 2011

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Elizabeth,
If you had looked in the index of your chemistry book, it would have given you the page that defined it.

If you had searched on Google, it would have given you 84,900 hits with an answer.

But since you did not, it is the number of moles of solute per liter of final solution. It is used in biology very extensively, but is not that great for chemistry as it does not consider valence. Normality does that.

James Watts
- Navarre, Florida
First of three simultaneous responses -- February 24, 2011

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Elizabeth,

This really sounds like you are trying to get us to do your homework for you. If you have looked at other answers in this section you will notice that we don't tend to give out free answers.

Look up molarity in any good school chemistry text book or at your school or local library. If you still don't understand and have specific questions come back to us and we'll be glad to help. Mind you, it will be far too late for you to complete your homework!

Brian Terry
Aerospace - Yeovil, Somerset, UK
Second of three simultaneous responses -- February 25, 2011

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Molarity is the mass of a substance divided by its molecular weight in each litre.
eg. with say a sulfuric acid (MW 98) solution if you had 196g/l the molarity would be 196/98= .2 Molar

Normality is however the mass divided by the equivalent weight which in the case of sulfuric acid is 49 because it has 2 active Hydrogen atoms so the normality of the above solution is 196/49 = 4 Normal

Geoffrey Whitelaw
- Port Melbourne, Australia
Third of three simultaneous responses -- February 25, 2011

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Molarity is simply the number of moles (gram molecular weight) of a substance in a liter of solution.

If you know the concentration in grams per liter, then simply divide this by the molecular weight. The result is the Molarity of the substance. Conversely, to make up a solution of a certain molarity, simply multiply the molarity by the molecular weight of the substance to find out how many grams per liter of the substance need to be added.

Lyle Kirman
consultant - Cleveland Heights, Ohio
February 25, 2011