How many drops of water can fit on a penny lab?
We had 27 drops of water on ours! Surface tension and cohesion is the reason you can get so many drops of water on a penny. Cohesion is the “stickiness” of like molecules to one another. Water molecules love to stick together!
Why does a drop of water stay on a penny?
The cohesive force that occurs between water molecules is so strong that, at the water’s surface, it creates a “skin”, which is known as surface tension. As drops of water are added onto a penny, the adhesive force between the water and the penny keeps the water from falling off.
How will putting soap on a penny affect the number of water droplets that fit on a penny?
This is because plain tap water has higher surface tension, so the surface is “stronger” and can hold together a larger drop. Adding soap lowers the water’s surface tension so the drop becomes weaker and breaks apart sooner.
How many drops of water can fit on a 5 cent coin?
Asked how many drops of water will fit on a five cent coin and most people predict two or three. In this surprising activity, students identify the many variables that affect the outcome and discover the answer can exceed forty drops!
Why did the coin did not float in the water?
The surface of the water curves down toward the edge of each coin. The coins are thus supported by the surface tension of the water. (Aluminum is denser than water and will not float, if the coins are pushed under water they sink to the bottom.) Two coins each depress the surface of the water.
How does soap make water wetter?
The detergent molecules also help to make the washing process more effective by reducing the surface tension of the water. The surfactant molecules of the detergent break apart these forces and make water behave, well, wetter!
Why can you place multiple drops on the head of a penny?
Water molecules are attracted to each other, so they tend to try to stick together (cohesion). This cohesion causes surface tension, which allows for the penny to hold more water drops then one would anticipate.
How does soap interact with water?
Soap breaks up the oil into smaller drops, which can mix with the water. It works because soap is made up of molecules with two very different ends. One end of soap molecules love water – they are hydrophilic. The other end of soap molecues hate water – they are hydrophobic.
What happens when two drops meet?
Two drops of liquid, at first separate and distinct, meet and come together to form a bigger drop. The problem of coalescence between two drops of liquid has generated a great deal of theoretical work and speculation that has been difficult to support by actual experiment.