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Topic: This molarity problem looks so simple!  (Read 4641 times)

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Offline dirknathan

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This molarity problem looks so simple!
« on: November 27, 2012, 03:27:44 PM »
Yet, I can't see the silver lining.

In a routine analysis a solution of sodium chromate with a chromium concentration of 75.0 ppm is required.  Calculate the molarity of the solution.

Now, does ppm equal mg/L?

Thanks for the *delete me*

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Re: This molarity problem looks so simple!
« Reply #1 on: November 27, 2012, 03:30:18 PM »
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Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #2 on: November 27, 2012, 04:36:49 PM »
Well, is it relevant to this problem?

Offline Hunter2

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Re: This molarity problem looks so simple!
« Reply #3 on: November 27, 2012, 05:05:44 PM »
Yes it is.

Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #4 on: November 27, 2012, 06:09:00 PM »
How do I relate the Sodium to that of mg/L?

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Re: This molarity problem looks so simple!
« Reply #5 on: November 27, 2012, 06:35:11 PM »
Through the molar masses. What molar concentration of sodium chromate has 75 mg Cr per liter?
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Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #6 on: November 28, 2012, 12:28:21 AM »
I've figured out the molarity of Cr.  how does one find the molarity of the entire solution with the molarity of one part? 

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Re: This molarity problem looks so simple!
« Reply #7 on: November 28, 2012, 12:42:15 AM »
Mole is the base. How many Chromium atoms you have in one molecule Chromate? If you know the mole of Chromium then you also know it from the Chromate then.

Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #8 on: November 28, 2012, 11:51:01 AM »
What about the oxygena in Chromate?

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Re: This molarity problem looks so simple!
« Reply #9 on: November 28, 2012, 01:40:30 PM »
Does the presence of oxygen change the concentration of chromium?
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Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #10 on: November 28, 2012, 01:54:14 PM »
Chromate*

Offline Hunter2

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Re: This molarity problem looks so simple!
« Reply #11 on: November 28, 2012, 01:58:35 PM »
What is the formula of  sodium chromate.
If you know this 1 mole of it containd how many mole sodium, chromium and oxygen.

Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #12 on: November 28, 2012, 02:28:18 PM »
Na2CrO4

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Re: This molarity problem looks so simple!
« Reply #13 on: November 28, 2012, 02:31:08 PM »
Great.
If you have 1 mol of sodium chromate, how many moles of sodium it contains, the same for chromium and oxygen.

Offline dirknathan

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Re: This molarity problem looks so simple!
« Reply #14 on: November 28, 2012, 02:52:10 PM »
So two moles of Na, 1 of Cr and 4 of O?  Now do they all have 75 ppm?

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