In the detetmination of calcium carbonate in limestone by classic titration, I got the abnormal value. I can not find what's the mistake. Here is what I did.
I took 0.2 gram sample, added 40 ml of 0.5 M HCl. The unreacted acid was titrated with 0.25 M NaOH. Volume of NaOH used was 49.4 ml.
The moles of acid reacted with Limestone is converted to moles of calcium carbonate, and converted to percent value.
The percent value I get is more than 100. As according to my calculations, there is about 0.3 gram calcium carbonate in 0.2 gram sample which is not possible.
Can anyone kindly indicate where is the mistake.
Thanks