Write the observations and explain the reason of this experiment.
Activity 3
1. 1 mL of water was transferred into well D6(a plate) by the pipet labeled “water”.
2. An additional 1 mL of isopropanol on top of the water was gently pipetted.
3. Observations were recorded in the Observations section.
4. A pinch of pepper was added to each well, allowing it to float or sink as it may.
5. Observations were recorded in the Observations section.
6. A wooden splint was used to stir the water and isopropanol, and observations were recorded in the Observations section.
3.) Water is denser than isopropanol. When isopropanol is added slowly, the difference in density allows the two liquids to remain separate as two distinct layers.
But when isopropanol is not added slowly, an azeotropic mixture (a constant boiling point mixture) is formed. This happens as Isopropyl alcohol can form strong hydrogen bonds with water molecules.
5.) The surface tension of the water is high due to hydrogen bonding. When pepper is added to water, they remain suspended.
The Surface tension of isopropanol is much lower than that of water, so when pepper is added to isopropanol, it sinks to the bottom
When isopropanol is added slowly to water (as in step 1) and pepper is added to the well, most of the pepper moves through the isopropanol layer and remains suspended at the surface of the water layer
6.) When the wood splint is gently pushed into the pepper and water mixture, the pepper prevents the water from contacting the splint. The high surface tension of the water allows the pepper to rest on the surface of the water. The pepper has no attraction to the water molecules and is, therefore, hydrophobic. It forms a water-resistant shield around the wood splint, keeping it dry while initially submerged and creating a small “pocket” in the water. The adhesion of pepper to water is stronger than that of pepper to the splint. Therefore, when the splint is lifted out of the well, it is clean.
When the wooden splint is used to stir the mixture of water, isopropanol and suspend pepper (as in step 6), it penetrates the pepper layer and the wood comes in contact with the water. Upon lifting the splint out of the water, the wood pulls up both pepper and water. Adhesion occurs between water and wood, as well as between water and pepper.
Write the observations and explain the reason of this experiment. Activity 3 1. 1 mL of...