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Topic: Can you help me please?[Solubility]  (Read 6689 times)

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Offline an_ncka430_smnc

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Can you help me please?[Solubility]
« on: November 09, 2008, 10:28:14 AM »
The solubility of Na2CO3 at 30C is of 29 g /100 g water. The amount of water needed to dissolve 143 g of Na2CO3*10H2O to obtain a saturate solution at this temperature is .
« Last Edit: November 09, 2008, 10:40:19 AM by an_ncka430_smnc »
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Offline an_ncka430_smnc

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Re: Can you help me please?
« Reply #1 on: November 09, 2008, 10:29:48 AM »
oh...and sorry for the bad english... i'm an international pupil...
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Offline an_ncka430_smnc

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Re: Can you help me please?[Solubility]
« Reply #2 on: November 09, 2008, 11:45:36 AM »
Oh...and I forgot to mention... it is 30 Celsius
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Offline DrCMS

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Re: Can you help me please?[Solubility]
« Reply #3 on: November 09, 2008, 11:48:40 AM »
Your attempt is?
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Offline an_ncka430_smnc

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Re: Can you help me please?[Solubility]
« Reply #4 on: November 09, 2008, 12:00:55 PM »
well i wrote:

Na2CO3*10H20= A(Na)*2+A(C)+A(O)*3+10*(A(H)*2+A(O))=286

286 g solution.....106 g Na2CO3
143 g solution.....x

=> x=106*143/286=53 g Na2CO3

129 g solution.. 29 g Na2CO3....100 g water
                          53 g Na2CO3....y

=> y=53*100/29=182,75
I already have 180 g water... so I need 2,75 g. 
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Offline an_ncka430_smnc

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Re: Can you help me please?[Solubility]
« Reply #5 on: November 09, 2008, 12:01:41 PM »
is it ok? :(
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Offline DrCMS

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Re: Can you help me please?[Solubility]
« Reply #6 on: November 09, 2008, 12:07:36 PM »
Very close but you do not have 180g of water.
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Offline an_ncka430_smnc

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Re: Can you help me please?[Solubility]
« Reply #7 on: November 09, 2008, 12:18:20 PM »
286 g solution...180 g water
143 g solution...z

=> z= 180*143/286= 90 g water
So I need 92,75 g.  ???
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Offline DrCMS

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Re: Can you help me please?[Solubility]
« Reply #8 on: November 09, 2008, 12:20:03 PM »
Yes
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Offline an_ncka430_smnc

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Re: Can you help me please?[Solubility]
« Reply #9 on: November 09, 2008, 12:21:40 PM »
Oh, thank you  :)
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