A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions, and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?

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  1. Indicators are weak acids or bases that show a color change as hydrogen ion concentration in a solution varies or as a solution's pH changes. In the water, the indicators gently dissociate to produce ions.
  2. It is of three types natural indicators, artificial indicators, and olfactory indicators.
  3. Natural indicators are those that occur naturally in the environment such as Turmeric, Litmus, etc.
  4. Artificial indicators are those that are created in a lab or that are acquired by a chemical reaction that does not occur normally. Examples: Phenolphthalein, methyl orange, etc.
  5. Olfactory indicators are indications that, when added to an acid or a base, change the fragrance rather than changing color. Examples: Onion, clove oil

Using indicators:

  1. For differentiating between the two solutions we can use phenolphthalein because phenolphthalein is frequently employed as an indicator in acid-base titrations and turns colorless in acidic solutions and pink in basic solutions.
  2. Alternately, we may use turmeric, which is yellow in color. When turmeric paper is dipped into a basic solution, it turns red. With acid, turmeric paper does not change color.
  3. Also, Another indicator we can use is china rose. With acid, China rose solution produces a dark pink (magenta) color, and with base, a green color.

Therefore, using different indicators we can distinguish between the two solutions.

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