pukebox Posted October 15, 2004 Share Posted October 15, 2004 I have 3% of NaCl stock solution. How do I make these concentrations with only 3% of NaCl? How much distilled water do I need to dilute before I can get these concentrations? -> 0.2% -> 0.4% -> 0.6% -> 0.85% -> 1% -> 2% -> 3% Link to comment Share on other sites More sharing options...
YT2095 Posted October 15, 2004 Share Posted October 15, 2004 well 1`stly you`ll need a common denominator we`ll use ml. the 3% you don`t need to do anything with for the 2% put in 66.6 ml of your 3% soln into a 100ml flask and top the rest up to 100ml with your water using this 2% soln pour 50ml of it into an empty 100ml flask and fill that up to 100ml with water, there`s your 1% soln and just continue like this all the way down Link to comment Share on other sites More sharing options...
pukebox Posted October 15, 2004 Author Share Posted October 15, 2004 Hokey I'm kinda confused. It's 3% concentration of NaCl stock solution (I think). And why do I have to put in 66.6ml? Because it's 2% divided by 3%? So if I wanna find solve 0.85% it'll be 0.15% divided by 3%? Therefore I put in 5ml of my 3% solution into a 100ml flask, top the rest up to 100ml with water, pour 50ml into another 100ml flask, fill it up to 100ml and there's my 0.85%? Link to comment Share on other sites More sharing options...
YT2095 Posted October 15, 2004 Share Posted October 15, 2004 because 66.6 ml and 33.3 ml will make 100ml of 2% soln Link to comment Share on other sites More sharing options...
pukebox Posted October 15, 2004 Author Share Posted October 15, 2004 because 66.6 ml and 33.3 ml will make 100ml of 2% soln Okay.. but why not 50ml, or 40ml, y'know. Link to comment Share on other sites More sharing options...
YT2095 Posted October 15, 2004 Share Posted October 15, 2004 100ml is a nice neat figure to work with since we`re talking Percent, which is based on 100 and using ml is a nice tiny amount that doesn`t require Buckets or a microscope Link to comment Share on other sites More sharing options...
badchad Posted October 15, 2004 Share Posted October 15, 2004 I always use: C1 V1 = C2 V2 (concentration of solution 1)(volume of solution 1) = (conc. sol. 2)(vol. of sol. 2) This way you don't necessarily need a common denominator. For instance, we know solution #1 is 3%, (your stock). We also know the concentration we want (conc. #2). All you have to do is decide how much of number 2 you want. Using YT2095's 100ml, you'd set it up as: (3%) (V1) = (.2%)(100ml) Solve for v1. Remember 100 ml is the final volume. So in this case v1= 6.67. You.d put 6.67ml in 93.33 ml of water. Sound correct YT2095? (just an alternate way of doing it) Link to comment Share on other sites More sharing options...
pukebox Posted October 15, 2004 Author Share Posted October 15, 2004 thanks.. the formula helped Link to comment Share on other sites More sharing options...
YT2095 Posted October 15, 2004 Share Posted October 15, 2004 sure that`s fine too at the end of the day it`s only basic maths, whether it be ml gr marbles or baked beans, subdivision is just that, you`re perfectly right also. it just beats me that a simple answer wasn`t understood and a more complex one was? LOL )) Link to comment Share on other sites More sharing options...
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