Acid or Base and Chemistry of Taste

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Discussion Overview

The discussion revolves around the use of red cabbage indicator to determine the acidity or basicity of various substances. Participants inquire about the expected color changes of these substances when the indicator is added and whether they are classified as acids, bases, or neutral solutions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant lists several substances and asks for their expected color change and classification as acid, base, or neutral when using red cabbage indicator.
  • Another participant suggests finding a reference for the pH range and colors associated with the red cabbage indicator and makes a comparison to phenolphthalein.
  • A participant provides a method for making red cabbage indicator and describes its use as a pH indicator.
  • Several participants share their interpretations of the colors and classifications of the listed substances, with some expressing uncertainty about specific items like Pepto-Bismol, saline solution, and hydrogen peroxide.
  • There is a discussion about the nature of saline solution and whether it can be classified as an acid or base, with differing opinions on its pH effect.
  • One participant asserts that salt is a base based on external sources, while another challenges this claim, stating that salt is formed from an acid and a base and questioning the purity of the salt.
  • Concerns are raised about the potential reactivity of hydrogen peroxide with the indicator, which may affect color observation.

Areas of Agreement / Disagreement

Participants express differing views on the classification of certain substances, particularly saline solution and Pepto-Bismol. There is no consensus on the correct classifications or expected colors for all items listed.

Contextual Notes

Participants mention various assumptions regarding the pH of substances and the effects of dilution and composition on the indicator's behavior. The discussion includes references to the variability in definitions of saline solution and the potential for differing results based on the specific type of saline used.

Who May Find This Useful

This discussion may be of interest to students studying chemistry, particularly those exploring acid-base indicators and pH measurement techniques.

hotgurl1
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Can somebody tell me the color the following items turn when purple Cabbage Indicator is added:

Water
Hydrogen peroxide
Isopropyl alcohol
Saline solution
Aspirin
Pepto-Bismol
Alka-Seltzer
Tonic water
Vinegar

and can you tell me if the items listed above are Acid or Base or Neutral

Please and Thank uo:)
 
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Can you find a reference book or article which gives the pH range and colors for that "purple Cabbage" indicator material? Do you have any information about the composition of those listed materials so as to judge their effect on pH? You should be able to answer your own questions.

A quick guess is that the purple indicator may be much like phenolphalein in its pH behavior --- only a "quick guess", not necessarily the correct guess.
 
Okay I get it you want me to find the Ph scale which is the one below. Then you want me to google each item to find there ph and that should tell me the color that each one turn and if it is acidic, netural, or a base.
pH 2 4 6 8 10 12
Color Red Purple Violet Blue Blue-Green Greenish Yellow

Thank u
Symbolipoint
 
I kinda made a big mistake were using red cabbage indicators not purple, but when you make the substance its purple.
Here's how to make it:

Making Red Cabbage Indicator

Put 1/2 cup of finely chopped red cabbage leaves in a jar and add 1/2 cup of hot water. Stir and crush the leaves with a spoon so that the red pigment in the leaves colors the water.


Continue this crushing until the water has turned a distinct, rich purple color.


Strain the liquid through a coffee filter to separate it from the cabbage leaves and throw the leaves away.


***The remaining liquid is a pH indicator: a substance that can be used to determine the pH of a substance. ***
 
Use the key below to determine whether the substance is an acid, base or is neutral. Record your results in the Data Table.

If the indicator turns the test solution red or pink, the solution is an acid.

If the indicator and solution together are a purple color, this indicates that it is neutral—neither an acid nor a base.

If the indicator turns the solution blue or green, the solution is a base.
 
Can somebody tell me if I am right :-p, so far I have:

Item color acid/ base/ neutral

Water - purple - netural
Isopropyl alcohol-red-acid
Aspirin- dark pink- acid
Alka-Seltzer-blue-base
Tonic water-pink-acid
Vinegar-pinkish-Acid

Im missing:
Pepto-Bismol
Saline solution
Hydrogen peroxide

Can somebody tell me what they are and the color. I think there all bases beteween the color of blue and green but I am not sure. :confused:

Help please:blushing:
 
hotgurl1 said:
Can somebody tell me if I am right :-p, so far I have:

Item color acid/ base/ neutral

Water - purple - netural
Isopropyl alcohol-red-acid
Aspirin- dark pink- acid
Alka-Seltzer-blue-base
Tonic water-pink-acid
Vinegar-pinkish-Acid

Im missing:
Pepto-Bismol
Saline solution
Hydrogen peroxide

Can somebody tell me what they are and the color. I think there all bases beteween the color of blue and green but I am not sure. :confused:

Help please:blushing:

I would rethink the answer for isopropyl alcohol. The rest look good.

Regarding the 'missing' ones you show... remember that pepto-bismol is a product designed to treate heartburn (acid indigestion). Of course its pink which makes it hard to observe a color change of an indicator. Saline solution has several meanings, the simplest of which is saltwater solution. It also means a saltwater solution that is formulated to accomplish something (lactated Ringers, acetated Ringers, Phosphate Buffered Saline, etc...). Some of these other types of saline have been pH adjusted to physiological pH. Hydrogen peroxide is reactive with the indicator and may bleach it. If it is dilute enough, this may not happen very quickly and you can observe a color briefly. Most commercially available hydrogen peroxide has substances in it that stabilize the reactive peroxide against decomposition. Those stabilizers can be either acidic or basic...
http://www.h2o2.com/intro/faq.html#4
 
Thank you chemisttre.
Okay so far I have Saline solution as base and the color greenish blue is that correct.

I'm still missing
Pepto-Bismol
Isopropyl alcohol
Hydrogen peroxide
 
hotgurl1 said:
Thank you chemisttre.
Okay so far I have Saline solution as base and the color greenish blue is that correct.

I wouldn't think so. Does dissolving salt (NaCl) into water affect pH? What is physiological pH?
 
  • #10
I know That Salt is a base by looking through other websites that used salt to perform this experiment.
 
  • #11
hotgurl1 said:
I know That Salt is a base by looking through other websites that used salt to perform this experiment.

Those websites were wrong about salt...
 
  • #12
salt is the substance formed when an acid reacts with a base, eg. HCl+NaOH=NaCl+H2O so it is neither an acid or a base, but some residual NaOH can make it basic, NaOH is a strong base so even a little would turn it basic
what is your margin of error?
how pure is the salt?
hotgurl1 said:
Thank you chemisttre.
Okay so far I have Saline solution as base and the color greenish blue is that correct.

I'm still missing
Pepto-Bismol
Isopropyl alcohol
Hydrogen peroxide
Think of what pepto-bismol would normally be used for
 
  • #13
Caught in the act!

Your a student from Florida virtual school and you have posted an assignment. I have been notified and may have to take the necessary action!

FLVS
 

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