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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: an_ncka430_smnc on November 09, 2008, 10:28:14 AM

Title: Can you help me please?[Solubility]
Post by: an_ncka430_smnc 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 .

Title: Re: Can you help me please?
Post by: an_ncka430_smnc on November 09, 2008, 10:29:48 AM

oh...and sorry for the bad english... i'm an international pupil...

Title: Re: Can you help me please?[Solubility]
Post by: an_ncka430_smnc on November 09, 2008, 11:45:36 AM

Oh...and I forgot to mention... it is 30 Celsius

Title: Re: Can you help me please?[Solubility]
Post by: DrCMS on November 09, 2008, 11:48:40 AM

Your attempt is?

Title: Re: Can you help me please?[Solubility]
Post by: an_ncka430_smnc 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. 

Title: Re: Can you help me please?[Solubility]
Post by: an_ncka430_smnc on November 09, 2008, 12:01:41 PM

is it ok? :(

Title: Re: Can you help me please?[Solubility]
Post by: DrCMS on November 09, 2008, 12:07:36 PM

Very close but you do not have 180g of water.

Title: Re: Can you help me please?[Solubility]
Post by: an_ncka430_smnc 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.  ???

Title: Re: Can you help me please?[Solubility]
Post by: DrCMS on November 09, 2008, 12:20:03 PM

Yes

Title: Re: Can you help me please?[Solubility]
Post by: an_ncka430_smnc on November 09, 2008, 12:21:40 PM

Oh, thank you  :)