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Topic: Ions in Electrolyes Help Needed  (Read 4743 times)

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crh1415

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Ions in Electrolyes Help Needed
« on: March 20, 2006, 07:56:27 PM »
Hey there, I'm having some serious problems with my homework assignment.

I'm supposed to:

"Calculate the concentraion of all ions present in each of the following solutions of strong electrolytes"

The first problem is:

0.300 mol of Ca(NO3)2 in 100.0 mL of solution

Honestly, I'm totally clueless as to where to begin. I know that the two ions I need to calculate the molarity for are Ca2+ and NO3-

To begin would I divide 0.300 moles by 0.100 L to get the overall molarity?

All help is appreciated!

Offline Borek

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Re:Ions in Electrolyes Help Needed
« Reply #1 on: March 20, 2006, 08:07:19 PM »
To begin would I divide 0.300 moles by 0.100 L to get the overall molarity?

Yes. Don't forget that there are twice more NO3- then Ca2+.
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Offline mike

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Re:Ions in Electrolyes Help Needed
« Reply #2 on: March 20, 2006, 08:08:36 PM »
c = n/v so when you divide the number of moles of Ca(NO3)2 by the volume this will give you the concentration in solution of Ca(NO3)2. For every one mole of Ca(NO3)2 in solution you have one mole of Ca2+ and two moles of NO3-. Which means that the concetration of Ca2+ should be the same as Ca(NO3)2 and the concentration of NO3- should be twice the concentration of Ca(NO3)2
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crh1415

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Re:Ions in Electrolyes Help Needed
« Reply #3 on: March 20, 2006, 08:39:32 PM »
Ok great, thank you very much for the help Borek and Mike!

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