hi. Ive done this experiment that involves using a pH indicator called neutral red in order to get a rough estimate of its acidity. It's transitional range is 6,8-8,0. basically red=acidic, and yellow=basic. Im somewhat confused as to what this means in practice. Ive done a lot of googling, and this is what ive come up with:
According to wikepedia, it means that the coulour of the soulution will change somewhere
within this pH interval. A solution with ph higher than 8 will allways be yellow, and a solution with pH lower than 6,8 will always be red. But within that pH interval the colour could go either way.
according to that definition, a red solution could have a pH value of 6,8 aswell as a pH value of say 7,5, cause we dont know at which point within this intervall its going to switch colours, it just means it has to be somewhere
within that range.
according to another website, these two pH values - 6,8 and 8,0 - are the endpoints. a solution(with neutral red in it) will change colour at these two and only these two values(called the endpoints). a red solution(acidic) thats being titrated with a base will change over to yellow when the pH is 8,0. A yellow solution will switch to red at the pH value of 6,8. according to this definition, the point at which the solution changes colour is not some random point somewhere the transitional intreval. its fixed at either 6,8 or 8,0.
heres the link to the website http://science.jrank.org/pages/3552/Indicator-Acid-Base.html
the questions the paper is asking, is what conclusion can be drawn about the pH value of the liquid from looking at its colour(when neutral red has been added).
so yea.... im confused. can anyone help me clarify?