Surface Tension Lab
Surface Tension of Water
I. Purpose How does adding soap to water change its surface tension?
II. Background
Adhesion is the bond between two substances of different makeups. In water, adhesion allows it to stick to other surfaces. Cohesion is the bond between two of the same substances. A hydrogen bond is a type of cohesion in water in which the hydrogen atoms of one water molecule being attracted to the oxygen atom of another water molecule. In water, each molecule in the middle is pulled equally in every direction by neighboring molecules. The cohesion forces between water molecules at the surface of water is surface tension. The cohesion forms a “film like” layer on the surface of water. Some substances may reduce the cohesion of water by reducing the strength on the surface of water because another element is being added. These substances are called surfactants. Soap is an example of a surfactant because once dissolved in water it reduces its surface tension. This allows it to break hydrogen bonds and ultimately break the surface tension.
III. Hypothesis If soap is added to the water, then the number of drops the penny can hold will decrease compared to the amount of drops on the penny with water.
IV. Materials
Penny
Pipette
Water
Soap
Paper Towels
V. Data/Observations
Water Drops in Types of Water
# of drops in …show more content…
The control group (plain water) had more drops on the penny. The experimental group (soapy water) had less drops on the penny. The independent variable which was the soap being added to the water changed the dependent variable (the number of drops) because the soap in the soapy water lowered the surface tension of the water. The pattern in the number of drops among the plain water group was greater than the number of drops for the soapy water
I. Purpose How does adding soap to water change its surface tension?
II. Background
Adhesion is the bond between two substances of different makeups. In water, adhesion allows it to stick to other surfaces. Cohesion is the bond between two of the same substances. A hydrogen bond is a type of cohesion in water in which the hydrogen atoms of one water molecule being attracted to the oxygen atom of another water molecule. In water, each molecule in the middle is pulled equally in every direction by neighboring molecules. The cohesion forces between water molecules at the surface of water is surface tension. The cohesion forms a “film like” layer on the surface of water. Some substances may reduce the cohesion of water by reducing the strength on the surface of water because another element is being added. These substances are called surfactants. Soap is an example of a surfactant because once dissolved in water it reduces its surface tension. This allows it to break hydrogen bonds and ultimately break the surface tension.
III. Hypothesis If soap is added to the water, then the number of drops the penny can hold will decrease compared to the amount of drops on the penny with water.
IV. Materials
Penny
Pipette
Water
Soap
Paper Towels
V. Data/Observations
Water Drops in Types of Water
# of drops in …show more content…
The control group (plain water) had more drops on the penny. The experimental group (soapy water) had less drops on the penny. The independent variable which was the soap being added to the water changed the dependent variable (the number of drops) because the soap in the soapy water lowered the surface tension of the water. The pattern in the number of drops among the plain water group was greater than the number of drops for the soapy water