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### Topic: Determining amount of solute  (Read 4536 times)

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#### hightime

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##### Determining amount of solute
« on: November 15, 2007, 07:22:07 PM »
Well im encountering some probelms with a question im doing.

Q:The hemoglobin in red blood cells carries oxygen to body tissues. What amount of hemoglobin is in 25.0 mL of a hemoglobin soloution with a concentration of 1.90 x 10-3mol/L

a: v=25.0
c=1.90x10^3 mol/L

n=c x v
=1.90x10^3 mol x 25.0

now my question how the heck do i put this in my calculator  im thinking im doing something wrong with the 3 thing. this is because ive been getting the right answer whenever it isnt giving me the 3 thing. The correct answer in my book is 4.75 x 10-5 mol but i get nothing close to that. could someone please explain if im doing something wrong n my equation and how i input it into a calculator. Thanks

#### Sev

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##### Re: Determining amount of solute
« Reply #1 on: November 15, 2007, 07:43:52 PM »
Firstly, volume should be in Litres.  Secondly, concentration is 1.9*10-3 not 1.9*103.  Your calculator should have some kind of exponent key, if not, 1.9*10-3 is just 1.9/1000.

#### hightime

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##### Re: Determining amount of solute
« Reply #2 on: November 15, 2007, 08:16:27 PM »
okay thanks for the litres part i'm glad you caught that I can't believe I missed it.

so now i've arived at the 4.75 part but im wondering how they got 10-5 since im kind of confused still on it.

#### Sev

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##### Re: Determining amount of solute
« Reply #3 on: November 15, 2007, 08:21:44 PM »
Quote
so now i've arived at the 4.75 part but im wondering how they got 10-5 since im kind of confused still on it.

Well, 0.025L*1.9*10-3M = 4.75*10-5 mol.

• Mr. pH