Question

What will be the colour change of onion if we add lemon juice in it

Answer 1

The addition of lemon juice, which is acidic, to an onion may cause it to change color slightly, becoming lighter, though the change is not as distinct as with standardized pH indicators like methyl orange.

Step-by-step explanation:

The question of what will be the colour change of onion if we add lemon juice is related to the properties of natural pH indicators, which is a topic primarily studied in Chemistry. Onions contain flavonoid pigments that can change color depending on the pH level. Adding lemon juice, which is acidic, will likely lower the pH of the onion, but onions are not as reliable as standardized pH indicators like methyl orange. The color change in onions is less distinct and can vary, but they may become slightly lighter in color. This is somewhat analogous to the behavior of pH indicators like methyl orange, where adding an acid shifts the equilibrium to change the color of the indicator. In the case of methyl orange, the acid shifts the equilibrium towards the nonionized red form (HIn), while the base shifts it towards the yellow anion form (In⁻). While onions do not have a distinct color change like methyl orange, they can still be considered a form of natural indicator that undergoes subtle changes.

Answer 2

Adding lemon juice, which is acidic, to an onion can cause a slight alteration in the onion's color due to the reaction of natural pigments with acids. However, unlike pH indicators such as methyl orange, onions may not show a dramatic color change but may become slightly paler or brighter in color.

Step-by-step explanation:

When lemon juice, which is acidic, is added to an onion, it can potentially change the onion's color. This is because onions contain naturally occurring pigments that can react with acids. The change is similar to the effect seen with pH indicators like methyl orange. Methyl orange is a compound that changes color depending on the pH level of the solution it is in. When an acid is introduced, methyl orange shifts from a yellow form (In⁻) to a red form (HIn) due to the presence of additional hydronium ions (H₃O⁺), as explained by Le Chatelier’s principle.

In practice, the onion might not display a dramatic color change like a pH indicator as the pigments within an onion react differently. The acidity of lemon juice may slightly enhance the color of the onion, making it appear brighter or slightly paler, but a distinct color shift like that observed in indicators is unlikely.