27-02-2004, 22:11
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#16
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The Invisible Woman
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Re: Chemistry question :)
Incog gets out deckchair and drink,gets comfy and waits for Theodoric to arrive. slurp,slurp.
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Hell is empty and all the devils are here. Shakespeare..
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27-02-2004, 22:15
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#17
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Guest
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Re: Chemistry question :)
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Originally Posted by Xaccers
Didn't know where to put this so feel free to move it 
Here's something to frazzle your brains
You are provided with a solution containing 50ppm chloride ions. How many mls of this should be taken and diluted to produce 100ml of a 2.5ppm solution? |
ok ppm is mg/kg
you want 100mls or 0.1kg of solution with 2.5 mg/kg concentration - i.e. 0.25mg of chloride ion.
50ppm is 50mg of chloride ion per litre so you would take 0.005 ml of the original solution? (ignoring density effects  )
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27-02-2004, 22:16
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#18
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cf.mega poser
Join Date: Jun 2003
Posts: 16,687
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Re: Chemistry question :)
I'm waiting for Dr. Exacters to reply to my last post. What manners are that? Somebody gives an answer, the reply is: 'how did you arrive at that'?, and then he bloody disappears?
I want my grade. NOW!!!!!  (and feedback on how to improve my answer if/when it's wrong)
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Remember kids: We are blessed with a listening, caring government.
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27-02-2004, 22:18
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#19
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Inactive
Join Date: Jun 2003
Location: London
Posts: 2,974
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Re: Chemistry question :)
Quote:
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Originally Posted by Xaccers
Didn't know where to put this so feel free to move it
Here's something to frazzle your brains
You are provided with a solution containing 50ppm chloride ions. How many mls of this should be taken and diluted to produce 100ml of a 2.5ppm solution? |
It needs to be diluted by a factor of of 50/2.5 = 20. 1/20 of 100 is 5. So, take 5 ml of the 50 ppm solution and dilute to 100 ml.
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27-02-2004, 22:23
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#20
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Inactive
Join Date: Jun 2003
Location: London
Posts: 2,974
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Re: Chemistry question :)
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Originally Posted by Incognitas
Incog gets out deckchair and drink,gets comfy and waits for Theodoric to arrive. slurp,slurp.
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I've just noticed this. I'm obviously getting a reputation for something or other.
PS It's not specifically a chemistry question, more a maths question on proportions, the sort of thing that was taught in school when I was a young lad (mutter, mumble, things were different in my young days . . .).
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27-02-2004, 22:26
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#21
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Inactive
Join Date: Jun 2003
Location: Milling around Milton Keynes
Age: 49
Posts: 12,969
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Re: Chemistry question :)
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Originally Posted by danielf
Gut feeling is with pem, 5 mils, but something tells me it might be 5.263 or 4.762, but I haven't quite figured it out yet (ie, I may well be wrong).
To Ramrod, I think that may drop out of the equation...
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5ml is correct
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27-02-2004, 22:29
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#22
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Inactive
Join Date: Jun 2003
Age: 58
Posts: 5,566
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Re: Chemistry question :)
Am I going to get a "see me" written in red 
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27-02-2004, 22:32
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#23
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Guest
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Re: Chemistry question :)
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Originally Posted by Theodoric
It needs to be diluted by a factor of of 50/2.5 = 20. 1/20 of 100 is 5. So, take 5 ml of the 50 ppm solution and dilute to 100 ml.
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5ml of 50ppm solution = 5/1000 x 50 mg = 0.25mg
you are correct - my .005 was in kg/litres, not ml 
- can I have marks for my 'workings out' 
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27-02-2004, 22:34
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#24
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cf.mega poser
Join Date: Jun 2003
Posts: 16,687
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Re: Chemistry question :)
Quote:
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Originally Posted by Xaccers
5ml is correct
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Full marks to PEM then, as he got it first...
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Remember kids: We are blessed with a listening, caring government.
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27-02-2004, 22:42
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#25
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Inactive
Join Date: Jun 2003
Location: Tonbridge
Age: 59
Services: Amazon Prime Video & Netflix. Deregistered from my TV licence.
Posts: 21,960
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Re: Chemistry question :)
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Originally Posted by Debsy42
Am I going to get a "see me" written in red |
I'm probably getting extra homework
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27-02-2004, 22:45
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#26
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The Invisible Woman
Cable Forum Mod
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Re: Chemistry question :)
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Originally Posted by Ramrod
I'm probably getting extra homework |
That'll cut down your postings.
__________________
Hell is empty and all the devils are here. Shakespeare..
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27-02-2004, 23:16
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#27
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Inactive
Join Date: Jun 2003
Age: 58
Posts: 5,566
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Re: Chemistry question :)
Ramrod Me
sat at the back of the class 
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27-02-2004, 23:27
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#28
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Guest
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Re: Chemistry question :)
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Originally Posted by Debsy42
Ramrod Me
sat at the back of the class |
tries to be good at sport, so the 'nerd' sticker, falls off - and I got it wrong
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27-02-2004, 23:38
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#29
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Inactive
Join Date: Jun 2003
Location: Tonbridge
Age: 59
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Posts: 21,960
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Re: Chemistry question :)
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Originally Posted by Debsy42
Ramrod Me
sat at the back of the class |
It's really annoying because I actually got A level chemistry....but when you don't use it for 16 years....  
...but thanks for the moral support 
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27-02-2004, 23:42
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#30
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Inactive
Join Date: Jun 2003
Location: Nottingham
Age: 70
Posts: 1,382
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Re: Chemistry question :)
Quote:
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Originally Posted by Debsy42
Am I going to get a "see me" written in red |
See Me later, girl.............
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