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 LauraN1234 |
Nurses/Nursing students |
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Posts: 4963 (12/14/2009 3:41 PM) |
Thanks guys!
How would you prepare 5L of a 1 : 40 solution from a 1 : 25 stock solution? Give your answer to the nearest milliliter.I don't even know how to answer this one. I got 8000 mL, but that doesn't make sense.  Does 1 : 40 just mean a 40% solution?
Edited By: LauraN1234 12/14/2009 3:53 PM.
Edited 1 time.
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sweeti4509 |
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Posts: 3779 (12/14/2009 3:40 PM) |
sounds right to me.
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CoolBeans1403 |
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Posts: 269 (12/14/2009 3:49 PM) |
thats what I got as well
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Ives0509 |
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Posts: 1920 (12/14/2009 4:00 PM) |
25/40=0.625
0.625 x 5000 = 3125 So then the 3125mL of stock is what you would need for the 5L. |
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LauraN1234 |
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Posts: 4966 (12/14/2009 4:09 PM) |
Ives0509 wrote: Yeah I thought I was doing it backwards. But the formula I was using from my book is Volume Needed x Concentration Needed ------------------------------------------ Concentration Available So then it would be 5000mL x 40 / 25. The last question I did was 350 mL of 22% ethanol from 45% ethanol.. So 350mL x 22 / 45 = 171 mL, and that was right. So now I'm just confused. |
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abby since 1984 |
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Posts: 52528 (12/14/2009 4:12 PM) |
Here's your answer: all of this is unnecessary.
Those are some wonky questions. |
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OhManImScrewed |
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Posts: 18398 (12/14/2009 4:15 PM) |
I've personally never done a problem like this the whole time I was in nursing school. But from what I have done, (40/25) x 5000 makes sense to me.
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LauraN1234 |
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Posts: 4969 (12/14/2009 4:16 PM) |
 That's what I said Abby. I have a final tomorrow and have to get at least 78%, so I'm just going over some of the things I struggled with. The
stupid thing is that our teacher gave us this study guide, but no answers. Thanks a lot.
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LauraN1234 |
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Posts: 4970 (12/14/2009 4:18 PM) |
OhManImScrewed wrote: I think I'm just going to not worry about this one because all of the other ones I've done have made sense except this one. |
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