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Topic: molarity help  (Read 6749 times)

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Offline jasoncboy

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molarity help
« on: March 19, 2009, 12:27:39 AM »
If you were to prepare exactly of 1.00L of 5M NaCl solution, you would not need exactly 1.00L of water. Explain why

Offline Borek

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Re: molarity help
« Reply #1 on: March 19, 2009, 03:56:47 AM »
What would be final volume once you will add 5 moles of NaCl to 1L of water?
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Offline Loucust

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Re: molarity help
« Reply #2 on: March 19, 2009, 04:09:01 AM »
Is the question saying that you are adding 5 moles of NaCl to 1.00 L of water to make 1.00 L of 5M NaCl solution? And then asking why you would not need exactly 1.00 L of water?

If so then I can only guess because when making or using 5M of NaCl, the solution is not exact, probably because getting 5 moles of NaCl is difficult or equal mixing issues? Other than that maybe because you could make a larger stock solution?

But I might be reading the question wrong or just be plain wrong.

Offline Arkcon

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Re: molarity help
« Reply #3 on: March 19, 2009, 06:39:19 AM »
A 5 molar NaCl solution is very concentrated, almost saturated.  So, you can try it for yourself -- get a kitchen measuring cup of tap water, add a bunch of table salt, and see what happens.  That is not exactly how we perpare sodium chloride solutions in the lab, but it will teach you something very important.  Look at the volume after you've added lots of salt, and see what's happening.
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Offline AWK

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Re: molarity help
« Reply #4 on: March 19, 2009, 07:31:37 AM »
5 molar NaCl has density about 1.155 kg/dm3.
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Offline Arkcon

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Re: molarity help
« Reply #5 on: March 19, 2009, 08:30:55 AM »
5 molar NaCl has density about 1.155 kg/dm3.

jasoncboy:, can you use this, to give you a hint, about what will happen to the volume, if you mix 5 moles of NaCl with 1 L of water?
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