Testing Buffer Solutions with Cabbage Dye Indicator

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In summary, the conversation is about a person seeking help with a question regarding buffered solutions using a cabbage dye indicator. The question asks which solutions would still be buffered after the addition of certain drops of HCl or NaOH. The person receives a hint that the approximate pH of HCl is 2 and NaOH is 13-14 and must determine which solutions would still be buffered based on this information.
  • #1
pinky2468
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I am very stuck on this question and I am hoping someone can help me with this. We did this in lab and mine did not come out right, but I still have to turn it in and my lab teacher said to figure it out!
Buffer solutions using a cabbage dye indicator:
Which of these is a buffered solution after the addition of 5 drops of HCl, 10 drops HCl:
distilled water (I think no?)
0.1 M NaCl
pH 12 buffer
pH 2 buffer

Which if these is a buffered solution after 5 drops NaOH, 10 drops NaOH:
juice(pH around 4.5)
soda(pH around 3)
pH 12 buffer
pH 2 buffer

I know this is a loaded question, but I can't figure out which ones...HELP!
 
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  • #2
Hi pinky, a buffer is a solution that contains a mixture of acids and bases.. if an acid or base is added to the solution the pH won't change. If you add a solution to a buffer outside it's buffering range, the buffer will loose it's power.

So thinking of that, which do you think the correct answer will be to your own question? Hint: what is the approximate pH of HCl and NaOH?
 
  • #3
HCl is a pH 2 and NaOH is about pH-13-14 right? So, pH 2 is a buffer solution when HCl is added and not when NaOH is right? The rest I am still lost on!?
 

1. How does cabbage dye indicator work to test buffer solutions?

Cabbage dye indicator is made from red cabbage leaves which contain a natural pigment called anthocyanin. This pigment changes color in response to changes in pH levels. When added to a solution, the cabbage dye indicator will change color depending on the pH of the solution. This allows us to determine if the solution is acidic, basic, or neutral.

2. Why is it important to test buffer solutions?

Buffer solutions are used in many scientific experiments and processes to maintain a stable pH level. It is important to test buffer solutions to ensure that they are functioning correctly and maintaining the desired pH level. If a buffer solution is not effective, it can lead to inaccurate results or even failure of the experiment.

3. How do you prepare a cabbage dye indicator for testing buffer solutions?

To prepare a cabbage dye indicator, simply chop up red cabbage leaves and boil them in water. Strain the liquid and let it cool. This liquid can then be used as a pH indicator for testing buffer solutions.

4. What are the color changes to look for when testing buffer solutions with cabbage dye indicator?

The color changes of cabbage dye indicator are as follows: red or pink indicates an acidic solution, purple or blue indicates a basic solution, and green indicates a neutral solution. It is important to compare the color of the buffer solution to a control sample of the cabbage dye indicator to accurately determine the pH level.

5. Can cabbage dye indicator be used to test all types of buffer solutions?

Cabbage dye indicator can be used to test most types of buffer solutions, but it is not suitable for all types. This method works best for solutions with a pH range of 5-8. For solutions with a higher or lower pH, other indicators may be more appropriate.

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