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Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: BVanHeurck on May 24, 2022, 05:15:11 AM

Title: Determinining alkalinity of 0.1M NaHCO3 solution
Post by: BVanHeurck on May 24, 2022, 05:15:11 AM

Hi

For my job I'm trying to figure out a spectrophotometric method for alkalinity determination (https://www.sciencedirect.com/science/article/pii/S0043135498001687)

The standards needed to make the calibration curve require 0.1 M NaHCO3 diluted in artificial sea water. However, I need to know the starting alkalinity of my 1L of 0.1 M NaHCO3. This was made by dissolving 8.401 g of NaHCO3 powder in 1L of distilled water.

Can somebody help me out on how to do this? Can you calculate this or is a manual titration necessary? Google isn't helping so far and I'm a biologist in training, so not sure on how to proceed here.

Thanks!

Title: Re: Determinining alkalinity of 0.1M NaHCO3 solution
Post by: Borek on May 24, 2022, 06:03:45 AM

As far as I am aware there is no one, universally accepted definition of alkalinity, so it is a bit difficult to get into the details. From what I remember the main difference between different approaches boils down to the endpoint pH - so yes, in principle alkalinity of your solution can be calculated.

This is more or less kind of a buffer problem, how much acid to add to modify pH to get some particular value.