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What is the purpose of the indicator in a titration?

Indicator: It is a chemical reagent used to recognize the attainment of end point in a titration. After the reaction between the substance and the standard solution is complete, the indicator should give a clear colour change.

What is the function of an indicator?

The function of an indicator in a titration process is to determine the equivalence point when two solutions have reached neutralization. An indicator can either be internal or external. In chemistry, titration is an analytical technique used to ascertain the concentration of an unknown solution.

What is the role of indicator in chemistry?

Indicators are substances that are used to test whether a substance is acidic or basic ot neutral in nature. They change their color when added to a solution containing an acidic or a basic substance. Acidity and alkalinity relate to pH, they may also be known as pH indicators.

What is the purpose of an indicator used in acid-base titrations?

Titrations. Because a noticeable pH change occurs near the equivalence point of acid-base titrations, an indicator can be used to signal the end of a titration. When selecting an indicator for acid-base titrations, choose an indicator whose pH range falls within the pH change of the reaction.

What is an indicator write the name of an indicator?

Indicators are the substances which show a change in color when brought in contact with acids and bases. Indicator that is used most commonly is litmus which is extracted from lichens and is available either in the form of solution or in the form of paper strips known as litmus paper.

How do you make your own indicator?

Boil the kettle and pour the hot water in the bowl until it just covers the cabbage. Stir a little bit and then leave for five to ten minutes. The colouring you can see in the water is your indicator! Place the strainer over the second large bowl and pour off the liquid.

Why is grape juice an indicator?

Explain to her that the lemon juice is an acid. All acids will turn a blue liquid or indicator, red. Tell her that the grape juice is called an indicator because it will indicate (or tell) whether another liquid is an acid.

Is tomato an indicator?

Natural Indicator is a type of indicator that can be found naturally and can determine whether the substance is an acidic substance or a basic substance. Some examples of natural indicators are red cabbage, turmeric, grape juice, turnip skin, curry powder, cherries, beetroots, onion, tomato, etc.

What is a good pH indicator?

For example, common indicators such as phenolphthalein, methyl red, and bromothymol blue are used to indicate pH ranges of about 8 to 10, 4.5 to 6, and 6 to 7.5 accordingly. On these ranges, phenolphthalein goes from colorless to pink, methyl red goes from red to yellow, and bromothymol blue goes from yellow to blue.

Why is anthocyanin a pH indicator?

Anthocyanins may be used as pH indicators because their color changes with pH; they are red or pink in acidic solutions (pH < 7), purple in neutral solutions (pH ≈ 7), greenish-yellow in alkaline solutions (pH > 7), and colorless in very alkaline solutions, where the pigment is completely reduced.

How does a pH indicator work?

pH indicators detect the presence of H+ and OH-. They do this by reacting with H+ and OH-: they are themselves weak acids and bases. If an indicator is a weak acid and is coloured and its conjugate base has a different colour, deprotonation causes a colour change.

What happens to anthocyanin when pH decreases?

In acidic condition, some of the anthocyanins appear red. At lower pH, the flavylium cation formed enables the anthocyanin to be highly soluble in water. The decrease in water concentration increases the rate of deprotonation of the flavylium cation, thus reducing color stability [16].

How is red cabbage used as a pH indicator?


  1. Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage.
  2. Filter out the plant material to obtain a red-purple-bluish colored liquid.
  3. Pour about 50–100 mL of your red cabbage indicator into each 250 mL beaker.
  4. Add various household solutions to your indicator until it changes color.

Why is cabbage a good pH indicator?

Discussion: Red cabbage is useful as a pH indicator because the leaves contain a pigment molecule from the family of anthocyanins (shown below) which are responsible for many of the red/purple/blue colors observed in fruits and vegetables. In neutral solutions, the color observed is purple.

Why purple cabbage can be used as an indicator?

Red or purple cabbage has a water-based pigment in its dye called anthoyanin. This fancy pigment can be used as a pH indicator! It reacts by changing colour in acidic and alkaline environments. This beautiful purple liquid will change to a bright pink in acidic environments and green in alkaline environments!

What is the benefit of red cabbage?

Red cabbage is a good source of vitamin K and provides small amounts of calcium, magnesium, and zinc, which can help build and maintain healthy bones. Red cabbage is high in fiber, making it easier to digest foods and keep your digestive system healthy.