A student added few drops of phenolphthalein to an aqueous solution of sodium carbonate. state the change in colour . what will happen if he puts this coloured solution on a white cloth. will the colour on the cloth persist? why or why not?

Question

Answer

It's simple, when a student adds few drops of phenolphthalein to an aqueous solution of Sodium Carbonate, the colour of the phenolphthalein changes into pink because, Sodium Carbonate is a base. Ions present in the base, change the phenolphthalein into its ion and turn the solution pink.

When pink colour is added to the white cloth, there will be no change. Because, due to the acid base reaction, it becomes colourless, so the white cloth remains same.

Answer

Phenolphthalein is a weak acid, which is why when it is added in a strong base, it gives pink color and the color gets intense as the PH of the base increases. ... By adding HCL in the solution, the pink color of phenolphthalein will disappear

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Answer

Change in colour of phenolphthalein in presence of sodium carbonate
When a few drops of phenolphthalein is added to an aqueous solution of sodium carbonate, the colour of the solution changes from colourless to pink. This is because phenolphthalein is an acid-base indicator which changes its colour depending on the acidity or basicity of the solution. In this case, sodium carbonate is a basic solution which causes phenolphthalein to turn pink.

What will happen if the coloured solution is put on a white cloth?
If the coloured solution is put on a white cloth, the colour may or may not persist depending on the nature of the cloth. If the cloth is made up of natural fibers such as cotton or linen, the colour will most likely persist because these fibers are porous and absorbent, allowing the solution to penetrate deep into the fabric. However, if the cloth is made up of synthetic fibers such as polyester or nylon, the colour may not persist because these fibers are non-porous and do not absorb liquids easily.

Explanation
When phenolphthalein is added to sodium carbonate, it forms a complex which is soluble in water. This complex is responsible for the pink colour of the solution. When this solution comes in contact with a cloth, it may get absorbed into the fabric depending on the nature of the cloth. Natural fibers such as cotton or linen are more absorbent than synthetic fibers such as polyester or nylon. Therefore, if the cloth is made up of natural fibers, the colour will most likely persist. On the other hand, if the cloth is made up of synthetic fibers, the colour may not persist because these fibers are non-porous and do not absorb liquids easily. In such cases, the colour may be removed by washing the cloth with soap and water.

Answer

When he puts the coloured solution on white. Because, due to Acid base reaction, it becomes colourless, cloth remains same, no change in colour.

Answer

When phenolphthalein indicator is put into the aqueous solution of sodium carbonate it turns pink in colour which indicates that it is basic in nature. I don't know what happens when you keep this on a clean white cloth but if there are any salt like impurities present, then the base in the solution may react with it thus changing its colour.

Similar Class 10 Doubts

Wht is the colour of solution whn NaOh solution + phenolphthalein? whn Hcl added to this solution?thn aftr adding NaOH to abve solution? at last whf colour?

Explain why an aqueous solution of sodium chloride is neutral but an aqueous solution of sodium carbonate is basic (or alkalin e)?

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