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What Are Indicators & How Do We Use Them? | Chemical Tests | Chemistry | FuseSchool

while it is possible to quantitatively

measure the pH of a solution using a

device known as a pH meter there are

also ways to determine pH qualitatively

in this lesson we will learn about

indicators which help us indicate the pH

of a solution

an indicator changes color depending on

the pH of the solution analyzed because

of this they are also known as pH

indicators universal indicator is very

versatile as it can measure pH across

the entire scale from zero to 14 it is

not a single indicator but rather a

combination of various indicators if you

look at the color changes of universal

indicator according to the pH of a

solution you will find that it resembles

a rainbow if Universal indicator

solution turns deep red in a solution it

means that the solution is strongly

acidic with the pH of 1 to 2 if the

universal indicator solution turns green

it means that the solution is neutral

with a pH of 7 if the universal

indicator solution turns dark blue or

purple it means that the solution is

strongly alkaline

indicator paper works in exactly the

same manner litmus is another indicator

commonly found absorbed onto paper as

litmus paper blue litmus paper turns red

under acidic conditions pH less than 7

red litmus paper turns blue under

alkaline conditions pH greater than 7

phenolphthalein is an indicator commonly

used to determine the endpoint of a

strong acid strong alkali or weak acid

strong alkali titration it goes from

colorless to fuchsia pink at a pH of 8.2

methyl orange is used to determine the

endpoint of either a strong acid strong

alkali or strong acid weak alkali

titration it is read at a pH lower than

3.1 and yellow at a pH higher than 4.4

in conclusion indicators are substances

that change color at a certain pH the

point at which an indicator changes

color is known as its endpoint which can

be at any pH common indicators that you

will encounter are Universal indicator

litmus in the form of litmus paper

phenolphthalein and methyl orange