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ymst12 2012-6-25 07:55 PM

chemistry 急問

100cm3 of solution contains 1.325g of a mixture of anhydrous sodium carbonate and sodium chloride. 25cm3 of the solution requires 25cm3 of 0.1M hydrochloric acid for complete reaction. The percentage by mass of sodium carbonate in the mixture is ?
thx

小吉._. 2012-6-25 09:30 PM

[quote]原帖由 [i]ymst12[/i] 於 2012-6-25 19:55 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=333537183&ptid=19656265][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
100cm3 of solution contains 1.325g of a mixture of anhydrous sodium carbonate and sodium chloride. 25cm3 of the solution requires 25cm3 of 0.1M hydrochloric acid for complete reaction. The percentage  ... [/quote]呢條好似係CE?
唔使理NACL  直接攞CARBONATE同HCL寫條EQ計

buluku 2012-6-25 09:31 PM

Na2(CO3)+2HCl->H2O+CO2+2NaCl
no. of mole of HCl=0.1x(25/1000)
=0.0025
from eq., no. of mole of Na2(CO3): no. of mole of HCl=1:2
no. of mole of Na2(CO3)=0.0025/2=0.00125
mass of Na2(CO3)=0.00125x (23x2+12+16x3)=0.1325
The percentage by mass of sodium carbonate=0.1325/1.325x100%
=10%
好耐無計過數,你check下先

Zzlaz 2012-6-26 01:39 AM

[quote]原帖由 [i]buluku[/i] 於 2012-6-25 09:31 PM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=333546310&ptid=19656265][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]
Na2(CO3)+2HCl->H2O+CO2+2NaCl
no. of mole of HCl=0.1x(25/1000)
=0.0025
from eq., no. of mole of Na2(CO3): no. of mole of HCl=1:2
no. of mole of Na2(CO3)=0.0025/2=0.00125
mass of Na2(CO3)=0.00125x ... [/quote]

100CM^3 抽25CM^3

buluku 2012-6-26 05:10 AM

[quote]原帖由 [i]Zzlaz[/i] 於 2012-6-26 01:39 AM 發表 [url=http://www.discuss.com.hk/redirect.php?goto=findpost&pid=333572926&ptid=19656265][img]http://www.discuss.com.hk/images/common/back.gif[/img][/url]


100CM^3 抽25CM^3 [/quote]睇漏左tim~
以而家咁既形態考dse實死得
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