You are comparing the surface tension on two bodies of water: a fresh-water pond and a salt-water lagoon. Which one, if measured, would have a higher surface tension?
A: the fresh-water pond because it has a lower density
B: the salt-water pond because it has a higher density
C: the fresh-water pond because is has a lower pH
D: the salt-water pond because it has a higher pH
D: the salt-water pond because it has a higher pH
The correct answer is A: the fresh-water pond because it has a lower density.
Surface tension is the measure of the force exerted by the molecules in the surface of a liquid. It is caused by the cohesive forces between the molecules. In general, liquids with lower density tend to have higher surface tension.
Freshwater has a lower density compared to saltwater. This lower density results in a higher surface tension. Therefore, a fresh-water pond would have a higher surface tension compared to a salt-water lagoon.
The pH of the water (options C and D) does not typically have a direct effect on surface tension.
To determine which body of water would have a higher surface tension, we need to understand the factors that influence surface tension.
Surface tension is defined as the measure of how difficult it is to break or penetrate the surface of a liquid. It is caused by the cohesive forces between the liquid molecules, which tend to minimize the surface area. There are several factors that affect surface tension, including the nature of the liquid, temperature, and impurities.
In the given options, density and pH are mentioned as potential factors influencing surface tension. However, in this case, neither of these factors directly correlates with surface tension.
Density is the mass of a substance divided by its volume and is determined by the overall amount of material present. Surface tension, on the other hand, is influenced by the forces between the molecules at the liquid-air interface. While density can indirectly influence surface tension, it is not the primary determinant.
Similarly, pH is a measure of the acidity or alkalinity of a substance. While pH can affect the chemical properties of a liquid, it does not directly impact surface tension.
To compare the surface tension between the fresh-water pond and salt-water lagoon, we need to consider the nature of the liquid. In general, substances with a stronger intermolecular force, such as hydrogen bonding, tend to have higher surface tension.
Freshwater typically has a higher surface tension compared to saltwater due to the presence of fewer dissolved ions. When salt, such as sodium chloride, dissolves in water, it dissociates into positive sodium ions (Na+) and negative chloride ions (Cl-). These ions disrupt the intermolecular forces of water molecules, leading to a decrease in surface tension.
Therefore, the correct answer is:
A: The fresh-water pond because it has a lower density.
While density is not the sole determining factor for surface tension, fresh water generally has a higher surface tension compared to saltwater due to the absence of dissolved ions.