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Green_Velvet
Super Human HipHop Head
Registered: 07/26/02
Posts: 412
Loc: La La Land
Last seen: 15 years, 2 months
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I suck at story problems
#877189 - 09/11/02 07:40 AM (21 years, 6 months ago) |
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Is anyone better than me?
Johnny wants to preserve some tissue from a particularly prolific fruitbody so he can clone her in several days. He has a 1/2 pint wide mouth jar with a piece of polyfill stuffed through a small hole in the lid. He plans on using a mixture of distilled water and peroxide to preserve the tissue for several days. The peroxide he has is 3% h2o2 97% h2o. He wants to prepare a mixture of .0015 or .15% as recommended by Mycofile in the bulk neglect report. How much water and how much peroxide solution does he need to obtain such a mixture?
Or is Johnny wasting his time with numbers, as he could just as easily fill the half pint half way up with water, then throw in a glug or two of h2o2 in?
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Cubies4Me
Child of theShroom
Registered: 05/11/02
Posts: 146
Loc: Another Realm
Last seen: 20 years, 8 months
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Re: I suck at story problems [Re: Green_Velvet]
#877303 - 09/11/02 08:20 AM (21 years, 6 months ago) |
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by thinkin in my head i think thats a 10-1 ratio but i could be wrong.
-------------------- Livin comfortably numb, always and forever.
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Alkaloids
3,4,5-trimethoxyphenethylamine
Registered: 11/15/98
Posts: 743
Loc: pubis mons
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Re: I suck at story problems [Re: Green_Velvet]
#877393 - 09/11/02 08:45 AM (21 years, 6 months ago) |
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must be an accountant for worldcom *lol* j/k actually it is a 19 to 1 dilution. or maybe I am not working well today.
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,166
Loc: my room
Last seen: 19 days, 20 hours
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Re: I suck at story problems [Re: Green_Velvet]
#879172 - 09/11/02 10:19 PM (21 years, 6 months ago) |
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Edited by Anno (09/11/02 11:05 PM)
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comario2
amateur
Registered: 09/06/02
Posts: 1,352
Loc: between places
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Re: I suck at story problems [Re: Anno]
#879493 - 09/12/02 01:31 AM (21 years, 6 months ago) |
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lovely, i'm framing this on my wall ....
-------------------- comario "crusaders against emotional poverty"
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DinoMyc
Ipsa scientiapotestas est
Registered: 11/13/99
Posts: 1,080
Last seen: 17 years, 9 months
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Re: I suck at story problems [Re: Anno]
#879615 - 09/12/02 02:38 AM (21 years, 6 months ago) |
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I do not understand your graphic at all.. is it trying to say: ( 3% * 1 unit + 0% * 19 unit ) / 20 unit = .15% ?
as it stands you have 0 -.15% = .15 parts = 1 part and simmilarly with water %... but why the water % initially is 3 %, I do not understand..
-------------------- If I made affront, I apologize. If I made affirmation, I apologize. I merely came to listen, came to say.
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,166
Loc: my room
Last seen: 19 days, 20 hours
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Re: I suck at story problems [Re: DinoMyc]
#879672 - 09/12/02 03:14 AM (21 years, 6 months ago) |
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So....
Is a simple balance that is written in this form for easier solving.
You do it the following way:
You have a solution with 3% of your wanted matter(peroxide) And you have a second solution with a different concentration, in our case 0% peroxide in water.
You want to have a solution with 0.15% peroxide.
What you do is you write the concentrations of both of your solutions one under eachoter.
Peroxide 3%
Water0%
And you write the desired concentration of the resulting solution on the middle right:
Peroxide 3%
Solution0.15%
Water0%
Now you deduct the value of the desired solution(0.15) from the peroxide concentration(3-0.15) and write it down where you have the Water concentration.
Peroxide 3%
Solution0.15%
Water0%2.85
The same with the water. If the result is smaller than 0, take the absolute value of it:
Peroxide 3%0.15
Solution0.15%
Water0%2.85
Now you already got the result! You have to take 0.15 parts of Peroxide, and 2.85 parts of water.
If you divide both concentration by the smaller one, you get the result in whole parts:
Peroxide 0.15/0.15 = 1
Water 2.85/0.15 = 19
That?s it.
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,166
Loc: my room
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Re: I suck at story problems [Re: DinoMyc]
#879690 - 09/12/02 03:30 AM (21 years, 6 months ago) |
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The same in equation form, a mass balance.
Water Mass: W Peroxide Mass: P
The pure peroxide that is in both solutions have to be the same when you have both solutions separately and after you mix them together. The equation:
0% x W + 3% x P = 0.15% (W+P) 0% x W + 3% x P = 0.15% x W + 0.15% x P (0%-0.15%) x W = (0.15% - 3%) x P -0.15% x W = -2.85% x P
W = -2.85/-0.15 x P = 19 x P
So, you have to take 19 times as much water as peroxide.
quot erat demonstrandum
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Green_Velvet
Super Human HipHop Head
Registered: 07/26/02
Posts: 412
Loc: La La Land
Last seen: 15 years, 2 months
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Re: I suck at story problems [Re: Anno]
#879999 - 09/12/02 06:06 AM (21 years, 6 months ago) |
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Thanks alot Anno. That really cleared things up for me. You solved the story problems, but how important is this ratio of peroxide to water? Lets say I guestimated and came up with a solution that was 1 part 3% peroxide 10 parts water. Or perhaps 1 part 3% peroxide 30 parts water. Would both solutions be okay to preserve tissue for several days before putting on peroxidated agar? How about straight 3% peroxide?
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DinoMyc
Ipsa scientiapotestas est
Registered: 11/13/99
Posts: 1,080
Last seen: 17 years, 9 months
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Re: I suck at story problems [Re: Anno]
#880130 - 09/12/02 08:00 AM (21 years, 6 months ago) |
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(this is more in response to the graphic, at first, than the post) but you do not have 0% water.. you have 100% water and 97% water.. 0-.15 = (-).15... I am not disagreeing with the results, I am just totally confused by the graphic/math that you used.. I am somewhat well educated in math and chem., so it is not an issue of concept.. its just the method you have many things which are simply not true.. like 3% = .15%, due to the 0% water.. now that you explained the division between the upper and lower paths, it graphic makes more sense, although a label of sol1 sol2 would be nice, the numbers still make no sense to me.. the formula I gave is what, I think, your trying to express.. I left mine purely in terms of concentration of peroxide, however.. its probably only a difference in notation somewhere.. in the post I?m dropping this reply to, your math is closer to mine.. Also, Quod Erat Demonstrandum is inappropriate in this context... and is usually reserved for those with PhD's in math or an appropriately logical discipline (not me.. yet, I hope), e.g. neither philosophy nor political science.. Quod Erat Faciendum is, however, appropriate.
enjoy your day.. and please accept my following apology: I know this is nitpicking.. the result is identical.. I just do not like being confused by a problem, so I want to understand how you were approaching it.... to me, at least, 3/.15 is easier than all that extra work..
-------------------- If I made affront, I apologize. If I made affirmation, I apologize. I merely came to listen, came to say.
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Anno
Experimenter
Registered: 06/17/99
Posts: 24,166
Loc: my room
Last seen: 19 days, 20 hours
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Re: I suck at story problems [Re: DinoMyc]
#880690 - 09/12/02 01:47 PM (21 years, 6 months ago) |
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>to me, at least, 3/.15 is easier than all that extra work.. Lol, off course it?s easier. But only if the solvent 2 contains 0% of H2O2(or any substance for that case). And the result would be 20, which is not exact, since the amount of water added should be 19 times the amount of peroxide.
Try to apply your calculation in mixing a peroxide solution with 3% and one with 7% with the resulting mixture of 2%.
I with my calculation can tell you imediately, in 3 seconds, that you will need 5 parts of the first, and 1 part of the second solution. What you have to do is deduct 2 from 7 (gives the parts for the first solution) and 2 from 3 (gives the parts for the second solution).
Peroxide 3%5
Solution2%
Water7%1
>but you do not have 0% water.. you have 100% water and 97% water.. You have a concentration of 0% H2O2 in the clean water. The matter that is calculated upon is H2O2, not water.
>I left mine purely in terms of concentration of peroxide, however.. Mine is too...
Edited by Anno (09/12/02 01:51 PM)
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cnidarium
radiallysymetric
Registered: 07/22/02
Posts: 47
Loc: benthic
Last seen: 15 years, 9 months
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Re: I suck at story problems [Re: Anno]
#881922 - 09/13/02 10:53 AM (21 years, 6 months ago) |
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how about 2.4 teaspoons of peroxide per cup of total volume.
do 2 and a short half teaspoons into a measuring cup. fill to one cup. Multiply the 2.4 times however many cups you want.
if you want to do it in metric 50 ml of h2o2 diluted to one liter.
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