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SlyPhoenix · Apr 21, 2009, 10:35 AM

The molecular weight of NaCl is 58.44 grams/mole. If you had a 1.0 molar solution (1.0 M) you would have to put 58.44 g of salt in 1.0 liter of solution.

How many moles of NaCl would you have in 100 mL of this solution?

Unknown008 · Apr 21, 2009, 10:42 AM

If you have 1 mole in 1 litre, how many do you expect to have in 100mL?

It's simple proportion. There'll be, of course, less moles than in a liter. Post back your answer to see if you got it right, k? :)

SlyPhoenix · Apr 21, 2009, 11:00 AM

I know I just can't remember how to convert

I know you have to set it up like

58.44 100mL
_________ x ____________
over something over something

but I can't remember how

Unknown008 · Apr 21, 2009, 11:05 AM

This question doesn't involve the mass of NaCl.

Ok, your answer should be 0.1mol in 100mL

Working:
1 L = 1000mL -> 1 mole
1mL -> 1mole / 1000 mL
100mL -> 0.001 x 100 mL -> 0.1 mole

If you were asked concentration in grams per 100mL, then, you'll have to include 58.44g in your calculations.

SlyPhoenix · Apr 21, 2009, 11:09 AM

So would the answer be

5.8 or 5.84?

Unknown008 · Apr 21, 2009, 11:10 AM

Originally Posted by Unknown008

This question doesn't involve the mass of NaCl.

Ok, your answer should be 0.1mol in 100mL

Working:
1 L = 1000mL -> 1 mole
1mL -> 1mole / 1000 mL
100mL -> 0.001 x 100 mL -> 0.1 mole

If you were asked concentration in grams per 100mL, then, you'll have to include 58.44g in your calculations.

See it? Lol! :p

SlyPhoenix · Apr 21, 2009, 11:13 AM

I understood how you got 0.1

Unknown008 · Apr 21, 2009, 07:15 PM

Great then! Understanding is lots better than seeing the answer and just copying! :)