[rleung]

Hi,

Sorry for the barrage of questions lately....but I am confused about one thing on this acid neutralization problem.  It says that a 2.50-g sample of a mixture of sodium carbonate and sodium chloride is dissolved in 25-mL of 0.798 M HCl.  Some acid remains after treatment of the sample.  The thing I don't get is how there is some acid that remains after the treatments are placed together.  Here is the equation for the reaction and the molar concentrations for the ICE chart(I left out Nacl since that really doesn't appear to contribute to anything)

Na2CO3(s)       + 2HCl(aq)       => 2NaCl(aq) +    H2O +    CO2

2.3x10^-2 mol    2x10^-2 mol         0                  0          0
-1x10^-2 mol     -2x10^-2 mol        +2x10^-2 mol for all 3 products
1.3x10^-2 mol    0 mol                   2x10^-2 mol for all 3 products

All the HCl appears to be used up, and there is no more acidic species.  I don't see how this solution can still be acidic.  Thanks so much.  Any input would be great.

Ryan

[wereworm73]

Only part of the 2.50 g sample is sodium carbonate, which means you have less than .023 moles of it.

[rleung]

Ahh!  I see...thanks so much!

Ryan