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Topic: Calculate the Concentration of a Mixture?  (Read 9009 times)

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Offline getfirefox

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Calculate the Concentration of a Mixture?
« on: March 14, 2010, 10:35:23 AM »
How do I work out the concentration of I- ions in each of the 5 mixtures with differnt volumes in?

Thanks guys!


Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #1 on: March 14, 2010, 10:43:03 AM »
What is the total volume of your solutions? How much KI do you have initially?

Offline getfirefox

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Re: Calculate the Concentration of a Mixture?
« Reply #2 on: March 14, 2010, 10:45:08 AM »
What is the total volume of your solutions? How much KI do you have initially?
Its just a question in a book.

The total volume of mixture 1 would be 10cm3 wouldn't it (simply add across the table)?

Same for all of them.

Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #3 on: March 14, 2010, 10:58:28 AM »
At a simple level, yes, the volume is additive.

So how are the concentration and volume related, for a given amount of substance?

Offline getfirefox

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Re: Calculate the Concentration of a Mixture?
« Reply #4 on: March 14, 2010, 11:03:35 AM »
At a simple level, yes, the volume is additive.

So how are the concentration and volume related, for a given amount of substance?
I have no idea dude.

I'm given that the potassium iodide is at 1.00moldm3 and the volumes in the table?

How do I work out the concentration of the iodide ions?

Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #5 on: March 14, 2010, 11:08:22 AM »
OK, If you have 1.00 mol dm-3, how many moles in 5.0 cm-3?

Offline getfirefox

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Re: Calculate the Concentration of a Mixture?
« Reply #6 on: March 14, 2010, 11:09:07 AM »
OK, If you have 1.00 mol dm-3, how many moles in 5.0 cm-3?
5 moles?

Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #7 on: March 14, 2010, 11:10:38 AM »
No, not 5 mol. How many cm3 in 1 dm3 ?

edit typo

Offline getfirefox

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Re: Calculate the Concentration of a Mixture?
« Reply #8 on: March 14, 2010, 11:11:56 AM »
No, not 5 mol. How many cm3 in 1 dm3 ?
1000cm3

(edit, sorry, cut and paste)
« Last Edit: March 14, 2010, 11:13:11 AM by sjb »

Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #9 on: March 14, 2010, 11:14:23 AM »
OK, so if there are 1000 cm3 in 1 dm3, and you have 0.1 mol in 1 dm3, how many moles in 1000 cm3? In 5 cm3?

Offline getfirefox

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Re: Calculate the Concentration of a Mixture?
« Reply #10 on: March 14, 2010, 11:18:59 AM »
OK, so if there are 1000 cm3 in 1 dm3, and you have 0.1 mol in 1 dm3, how many moles in 1000 cm3? In 5 cm3?
So it would be:

1.00moldm-3 / 1000

= 0.001 moles in 1000cm3

So in 5cm3, it would be

0.001mol x 5cm3

= 0.005moldm3 for Mixture 1 in the table.

Is that right (are the units right for the final answer too)?

Offline sjb

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Re: Calculate the Concentration of a Mixture?
« Reply #11 on: March 14, 2010, 12:23:07 PM »
The number is right for the initial solution (before dilution), but the units are not. mol dm-3 x dm3 = ?

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