In three test tubes A,B and C , the different liquids namely , distilled water, underground water and distilled water in which a pinch of calcium sulphate is dissolved , respectively are taken. Equal amount of soap solution is added to each test tube and the contents are shaken. In which test tube will the length of lather be longest? Justify your answer.
Answers
The test tube with the length of the foam (lather) longest is test tube A- Distilled Water.
- Lather forms easily in soft water. Distilled water is soft water hence later will form easily in test tube A .
- But underground water & water containing calcium sulfate contain calcium & magnesium salts. This will make water harder. They react with soap solution and forms scum due to calcium & magnesium salts with little lather. Hence Test tube B and C forms little lather and some scum.
So the test A with distilled water has the longest foam.
Answer:
Test tube A
Explanation:
Test tube A = Distilled water (Given)
Test tube B = Underground water (Given)
Test tube C = Distilled water with calcium sulphate (CaSO4) (Given)
The test tube with the length of the foam or lather that will be longest is test tube A- Distilled Water. This is because the soap added in water will easily form foam with distilled water. Lather forms easily in the soft water and since distilled water is soft water hence later will form easily in test tube A .
Underground water and water containing calcium sulfate (CasO4) contain both the calcium (Ca2+) and magnesium (Mg2+) salts, thereby making the water harder. Further, they react with soap solution and form a scum due to calcium and magnesium salts with little lather. Hence Test tube B and C forms little lather and some scum.
Hence, the test A with distilled water has the longest foam.