How does detergent change the physical properties of water?

Question

Luna Chen · Accepted Answer

Detergents will weaken hydrogen bonds that make water molecules stick to each other. This will decrease the surface tension of water.

Here is video showing how a paperclip can ""float"" on water - it's actually being held up by the hydrogen bonds formed between water molecules which give water its surface tension.

Video from: Noel Pauller

Notice how the paper clip sank after the addition of detergent to the beaker? That happened because the detergent molecule reduces the attraction of water molecules to each other by disrupting their ability to form hydrogen bonds. The addition of detergent reduced the surface tension of the water.

The reduction of surface tension by detergents is what allows water-detergent solutions to form large bubbles.

Hope this helps!

Ellie Andrews · Answer

undefined In addition to helping to emulsify and solubilize oily or greasy substances by encircling them and forming micelles, which keeps them suspended in the water rather than allowing them to separate out, detergent molecules also raise the pH of water, making it more alkaline, which can affect its chemical properties. Detergent molecules also break down the surface tension of water, allowing it to spread and wet surfaces more effectively.

Luna Chen · Answer

undefined Detergent molecules have hydrophilic (water-attracting) and hydrophobic (water-repelling) regions. When detergent is added to water, the hydrophilic part of the detergent molecule aligns itself with the water molecules, while the hydrophobic part interacts with nonpolar substances such as oil and grease.

This interaction disrupts the surface tension of water, reducing its ability to form droplets and allowing it to spread more easily. This property of detergents is why they are effective in cleaning, as they help to emulsify and lift away dirt and grease from surfaces.

Furthermore, detergents can also change the foaming properties of water. The hydrophobic tails of detergent molecules can stabilize air bubbles in water, leading to the formation of foam. This is why detergents are commonly used in soaps and shampoos to create lather.

Overall, detergents alter the physical properties of water by reducing surface tension, aiding in the emulsification of nonpolar substances, and promoting foaming.