Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: orgo814 on June 15, 2014, 08:51:07 PM
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This is a VERY basic question. I have not done lab work in chemistry for awhile and am just starting on research.
If I was to prepare a 0.7% NaCl solution, would I just add 0.7 grams of NaCl and then dilute it with 100 mL? This stuff has always confused me.
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Everybody find this sort of thing tricky, when they haven't done it in a while. A useful trick is to keep careful records in your lab book. As in, what did you want to make -- a 0.7 % solution. And how did you make it? The you can make a 0.5%, or 0.3 % next time.
At any rate, when you want to solve such a problem, try a couple of other, close by concentrations, such as 1%, and others. A 1% solution would require 1 gram in .what, 100 grams total solution weight. And 0.5% would be exactly half. And 0.7 would have to be between the two.
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If I was to prepare a 0.7% NaCl solution, would I just add 0.7 grams of NaCl and then dilute it with 100 mL? This stuff has always confused me.
Imagine preparing 50% solution with this approach. You take 50 g of NaCl, dilute with 100 mL of water (which weights almost exactly 100 g), so you end with 150 g of the solution.
[tex]\frac{50g}{150g}\times 100\% = 33.3\%[/tex]
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