Quiz 10.3 - Properties Of Liquids And Water

Hydrogen bonding is a type of intermolecular force that occurs when a hydrogen atom is bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and is attracted to another electronegative atom in a different molecule. In the case of HF (hydrogen fluoride), the hydrogen atom is bonded to a highly electronegative fluorine atom, and it can form hydrogen bonds with other electronegative atoms. Therefore, the statement that "HF exhibits hydrogen bonding" is true.

Vapor equilibrium refers to the balance between the rate of evaporation and condensation of a substance. In the given options, the observation that best illustrates vapor equilibrium is "Moisture is found underneath the lid of a closed food container." This observation suggests that the moisture inside the container is evaporating and condensing on the lid, indicating a state of equilibrium between the vapor and liquid phases. The other options do not directly relate to vapor equilibrium.

Capillary action occurs when a liquid rises in a narrow tube against the force of gravity. In this case, blood rising up the length of a narrow glass tube demonstrates capillary action because the narrowness of the tube allows for the cohesive and adhesive forces between the blood and the glass to overcome gravity and pull the blood upward.

Surface tension is the property of a liquid that allows it to minimize its surface area and form a spherical shape. This is due to the cohesive forces between the liquid molecules, which pull them together and create a "skin" or surface layer. This surface tension is what allows insects to walk on water, for example, as the cohesive forces hold the water molecules together and create a strong surface. Therefore, the correct answer is maintain a spherical shape.

Hydrogen bonding is a type of intermolecular force that occurs between a hydrogen atom bonded to a highly electronegative atom (such as oxygen or nitrogen) and another electronegative atom. This type of bonding is responsible for the unique properties of water, including its high boiling point and surface tension. The observation that even though water molecules have a low mass, water exists as a liquid is an example of hydrogen bonding. The hydrogen bonds between water molecules are strong enough to hold them together in a liquid state, despite the low mass of the individual molecules.

HBr does not exhibit hydrogen bonding because it does not contain a hydrogen atom bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. Hydrogen bonding occurs when a hydrogen atom is bonded to one of these highly electronegative atoms, creating a strong dipole-dipole interaction between molecules. In the case of HBr, the hydrogen atom is bonded to a less electronegative atom (bromine), so hydrogen bonding does not occur.

Capillary action occurs in narrow glass tubes because water has a greater attraction to glass than it has to itself. This is due to the adhesive forces between the water molecules and the glass surface being stronger than the cohesive forces between the water molecules themselves. As a result, the water molecules climb up the glass tube against gravity, creating the capillary action. The other options mentioned in the question, such as moisture collecting underneath the lid of the capillary tube, the composition of water, or the formation of spherical droplets inside the tube, are not relevant to the phenomenon of capillary action.

H3PO4, also known as phosphoric acid, is capable of exhibiting hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (in this case, oxygen) and forms a weak bond with another electronegative atom (such as oxygen or nitrogen) in a different molecule. In H3PO4, the hydrogen atoms bonded to the oxygen atoms can form hydrogen bonds with other electronegative atoms, leading to the statement that H3PO4 exhibits hydrogen bonding.

CH4, which is methane, does not exhibit hydrogen bonding. Hydrogen bonding occurs when a hydrogen atom is bonded to a highly electronegative atom (such as oxygen, nitrogen, or fluorine) and is attracted to another electronegative atom nearby. In CH4, the hydrogen atoms are bonded to carbon, which is not highly electronegative. Therefore, CH4 does not have the necessary conditions for hydrogen bonding to occur.

Surface tension is the force that causes the surface of a liquid to behave like a stretched elastic sheet. It is responsible for certain behaviors such as capillary action and the formation of droplets. The observation that mercury tends to form spherical droplets is the best illustration of surface tension because the cohesive forces between the mercury molecules cause them to minimize their surface area, resulting in a spherical shape. This is a characteristic behavior of liquids with high surface tension.