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pH calculation

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**light**:

the recipe:

0.1 M sodium carbonate buffer, pH 9.6 (Ambros Lab)

8 ml of 0.2M sodium carbonate (Na2CO3) (0.2M = 21.2 g/l)

17 ml of 0.2M sodium bicarbonate (NaHCO3) (0.2M = 16.8 g/l)

25 ml of water

...

i have calculated the pH of this buffer and found that it is not 9.6 but 10.0.

sodium carbonate (Na2CO3): (0.2Mx0.008L)/0.025L=0.064M

sodium bicarbonate (NaHCO3): (0.2Mx0.017L)/0.025L=0.136M

pH=pKa+log[base]/[acid]

pH=10.32+log(0.064/0.136)

pH=10

am i doing it right?

thanks for your input!

**AWK**:

sodium carbonate (Na2CO3): (0.2Mx0.008L)/0.025L=0.064M

sodium bicarbonate (NaHCO3): (0.2Mx0.017L)/0.025L=0.136M

The final volume is 50 mL (0.05 L) but this not change your result.

Haselbach equation gives quite approximated results, so all is OK at this approximation.

**light**:

thanks alot for your *delete me*

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