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Estimation of pH of solution based on color of 2 indicators

Please see the attached file for the fully formatted problems.

1. Estimate the pH of the following, based on the indicator colors given:
Solution Tested Bromocresol Green (indicator color) Bromothymol Blue (indicator color) Estimated pH
Distilled water Blue Yellow ?

Distilled water with 4 drops of acetic acid Yellow Yellow ?

Distilled water w/ small sample NaHCO3 Blue Blue ?

Distilled water w/ NaHCO3 and 6 drops of acetic acid Blue Yellow ?

Ordinary Tap Water Blue Green ?

Tap water w/1 drop of acetic acid Yellow Yellow ?

2. What effect does adding acid have to the pH of our water?

3. Why would it take more drops of acetic acid to change the pH when sodium bicarbonate is dissolved in the water?

4. What kind of a system do acetic acid and sodium bicarbonate (NaHCO3) form?

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Solution Preview

Solution Tested Bromocresol Green (indicator color) Bromothymol Blue (indicator color) Estimated pH
Distilled water Blue Yellow Greater than 5.4 but less than 6.0
REASON: BG has changed, but BB has not

Distilled water with 4 drops of acetic acid Yellow Yellow 3.8 or less
REASON: both are in their low pH form

Distilled water w/ small sample NaHCO3 Blue Blue Greater than 7.6
REASON: both are in their high pH ...

Solution Summary

Data is given for the color of two indicators, bromocresol green and bromothymol blue, in various solutions. The pH is estimated and a full justification given. There are 3 other questions regarding buffers and the effect of acid on a buffered and unbuffered solution that are fully explained.

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