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Topic: A fun mole question  (Read 7961 times)

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Offline noiseordinance

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A fun mole question
« on: April 04, 2009, 01:50:59 PM »
Hey there. To start, I have really gotten the concept of moles / mass percent, etc. very well. I'm really stumped on a question however, and would really like some help figuring out the plan of attack. I don't want the answer, just the direction. Here's the question:

Quote
Hemoglobin, a protein in red blood cells, carries O2 from the lungs to the body's cells. Iron (as ferrous ion, Fe2+) makes up 0.33 mass % of hemoglobin. If the molar mass of hemoglobin is 6.8x104 g/mol, how many Fe2+ ions are in one molecule?

I've attacked this several ways and I'm just stuck. Can anyone offer some pointers?

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Re: A fun mole question
« Reply #1 on: April 04, 2009, 02:28:32 PM »
How many grams of iron per 1 mole of hemoglobin?
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Offline Squirmy

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Re: A fun mole question
« Reply #2 on: April 04, 2009, 05:18:13 PM »
Is there any other way you could express 0.33 mass %?

A tip: be explicit with your units...  "g/mol" grams of what? moles of what?

Offline noiseordinance

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Re: A fun mole question
« Reply #3 on: April 04, 2009, 08:29:36 PM »
I originally came up with grams of iron per 1 mole of hemoglobin by taking (6.8x104 g/mol)(0.0033)=2.2x102 grams of iron... from there I'm totally lost. Do I use the mass percent to figure out empirical formula or something?

Offline ARGOS++

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Re: A fun mole question
« Reply #4 on: April 04, 2009, 08:37:32 PM »

Dear noiseordinance;

Now you have only one answer left to answer:
How many moles iron (Fe) are your 2.24 * 102 g iron?; and then you know how many mole Fe you have per mole HEM.

Good Luck!
                    ARGOS++


Offline noiseordinance

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Re: A fun mole question
« Reply #5 on: April 04, 2009, 09:51:40 PM »
Awesome. So is this one of those situations where I round? (My answer comes out to 4.01 Fe... dumb question but just making sure...)

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Re: A fun mole question
« Reply #6 on: April 05, 2009, 04:07:27 AM »
Yes.
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