Question

Determining the Calcium content of antacid tablets::

Would the following procedural errors cause the calculated calcium content to be too high, too low, or unaffected? Briefly explain

1) an insufficient amount of HCL was added to completely dissolve the sample.

2) the buret containing the standard calcium solution was not rinsed properly and contained some water at the time it was filled.

Answer 1

1

2HCl +Ca2+ -> CaCl2 + H2

if insufficient HCl is added then the actual number of moles of calcium reacting will be lesser than actual and Calcium content calculated will be less than actual

2.

If Some water is already present in buret before adding solution , it can lead to minor deviations from actual value. Reason behind this is that water present if is hard water will contain reidual amount of calcium.

This will lead to a higher calculated calcium content than actual