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# Find ppm of sodium based on cation-exchange

Reagents:
.02 M NaOH, 1M HCl, Bio-Rad Dowex 50W-X2 (100/200 mesh) cation-exchange resin, Unknown Saline Solution diluted to the mark given in a volumetric flask.

Procedure:
1. Prepare the resin column using Bio-Rad Dowex 50W resin.
2. While trying to minimize resin disturbance, add ~ 10 mL of 1 M HCl slowly into each column.
3. Allow the acid to drain to the point where the resin are still covered by liquid.
4. Do the same with ~ 10 mL DI water and repeat if necessary until the elute in no longer acidic.
5. Accurately and slowly pipette and transfer 5.00 mL of the unknown solution.
6. Collect the eluates until the liquid level just cover the resin follow by ~ 10mL of water.
7. Repeat the washing until no longer acidic.
8. Add 3-4 drops of phenolphthalein and titrate with standardized NaOH until a faint pink.

Determine the [NaCl] in ppm in the original diluted 100 mL flask.
I don't know how to calculate the concentration of NaCl and more specifically how in ppm. I can provide the numbers of NaOH that it was titrated with; however, what I need is how to do the calculation in general. I can figure my calculation out since it needs to have error propagation included.
To prepare standardize NaOH:
.7789 g NaOH

NaOH added to titrate 5.00 mL unknown solution: 34.80mL

#### Solution Preview

Hi there,

After carefully studying this question, here is my rationale:

For the cation-exchange resin, it will effectively capture the positively charged ion.
When HCl is applied, H+ is bound to the ...

#### Solution Summary

The solution provides detailed explanation how to find ppm of sodium based on cation-exchange.

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