WEEK4- LIQUID PROPERTIES

• Surface tension is the tendency of a fluid to acquire the least possible surface area. A drop of liquid is assumed to be spherical in shape due to the intermolecular forces of attraction present in the molecules of the liquids.
• Viscosity is affected by temperature. When the temperature is high, the molecules have more energy and it becomes easier to overcome the IMFA. This leads to lower viscosity.
• Matter can be described in terms of its physical state. The three basic states of matter are solid, liquid, and gas.
• Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid phase in a closed system. Molecules with stronger intermolecular forces have less tendency to escape into gas, and thus, have lower vapor pressure compared to those with weaker IMFA.
• Vaporization is the process where a fraction of the kinetic energy of a liquid escapes from the surface to enter the vapor phase. The enthalpy of vaporization (∆Hvap), also called the heat of vaporization, is the heat required to induce this phase change.
• In nature, there are attractive and repulsive forces. Some of these attractive forces also exist among very small particles of matter.
• Viscosity is the measure of a fluid’s resistance to flow. Liquids that flow easily have low viscosity while liquids that do not flow readily have high viscosity.
• The properties of liquids can be attributed to the intermolecular forces. These intermolecular forces of attraction are directly related to the surface tension, viscosity, and vapor pressure of the liquid.
• Liquids have intermediate intermolecular forces. This makes liquid particles farther from one another compared to those in solids.
• Have you ever observed small insects walking on the surface of the water?
• For liquids, viscosity decreases with increasing temperature, but for gases, the viscosity increases with increasing temperature.
• Cohesion is the attraction between like molecules, while adhesion is the attraction between unlike molecules.
• If a certain quantity of liquid is vaporized at a constant temperature
• Which will exert a higher vapor pressure?

  • water
  • acetone
• Water and ethanol both are polar substances capable of exhibiting the same IMFAs. When mixed together, they form a solution
• Hydrophilic substances


  Substances or molecules that form interactions with water
• The stronger the intermolecular forces between the solvent molecule and the solute molecule, the greater the solubility
• If a liquid has strong IMFA, it has low surface tension: False
• Vapor Pressure

  • Molecules with stronger intermolecular forces have less tendency to escape into gas and have lower vapor pressure compared to those with weaker IMFA
• Solubility


  Like dissolves like. When the solute and the solvent both exhibit the same intermolecular forces of attraction, they form a solution
• Hexane and water don’t have the same IMFA. Therefore, hexane and water form a heterogeneous mixture
• Surface tension


  The property of the surface of a liquid that allows it to resist an external force
• Evaporation is slower, occurs only from the surface of the liquid, does not produce bubbles, and leads to cooling. Boiling is faster, can occur throughout the liquid, produces lots of bubbles, and does not result in cooling
• Vapor Pressure


  The pressure exerted by a vapor in equilibrium with its liquid phase in a closed system
• Enthalpy of vaporization


  The amount of energy that must be added to a liquid substance to transform a quantity of that substance into a gas
• Solubility


  The ability of a substance to dissolve in a given amount of solvent at a specified temperature
• For liquids, viscosity decreases with decreasing temperature
• Substances with stronger IMFAs

  Have lower vapor pressure compared to those with weaker IMFA
• Viscosity


  The measure of a fluid’s resistance to flow
• Boiling Point

  The temperature at which a substance changes from liquid to gas
• If two liquids dissolve or mix together, they are called miscible liquids. If two liquids do not dissolve or mix together, they are called immiscible liquids
• Molecules with stronger IMFA have higher viscosity compared to those with weaker IMFA. Higher temperature leads to lower viscosity
• Hydrogen bonding makes the boiling point of water significantly higher than similar binary compounds of hydrogen and a Group 6A element
• Amphipathic molecules


  Molecules with both hydrophilic and hydrophobic regions
• Liquids that mix together are described as miscible
• When the solute and the solvent both exhibit the same IMFA

  They form a solution
• Hydrophobic substances


  Substances or molecules that repel water