What is the dispersion force? What does the magnitude of the dispersion force depend on? How can you predict the magnitude of the dispersion force for closely related elements or compounds?
Dispersion forces (aka London forces) are the result of fluctuations in the electron distribution within molecules or atoms. Because all atoms and molecules have electrons, they all exhibit dispersion forces. The electron in an atom or molecular may at an
What is dipole dipole force? How can you predict the presence of dipole-dipole forces in a compound?
Dipole-dipole force exists in all molecules that are polar. Polar molecules have permanent dipoles that interact with the permanent dipoles of neighboring molecules. The positive end of one permanent dipole is attracted to the negative end of another; thi
How is the miscibility of two liquids related to their polarity?
Miscibility is the ability to mix without separating into two phases. The rule of thumb is like dissolves like. IN general, polar liquids are miscible with other polar liquids, but are not miscible with nonpolar liquids. Nonplar liquids are miscible with
What is hydrogen bonding? How can you predict the presence of hydrogen bonding in a compound?
The hydrogen bond is a sort of super dipole-dipole force. Polar molecuels contating hydroen atoms bonded directly to fluorine, oxygen, or nitrgen exhibit an intermolecular dorce called hydrogen bonding. The large electroneagtivity difference between hydor
What is ion-dipole force? Why is it important?
The ion-dipole force occurs when an ionic compound is mixed with a polar compound and is especially important in aqueous solutions of ionic compounds. For example, when sodium chloride is mixed with water, the sodium chloride ions interact with water mole
What is surface tension? How does surface tension result from intermolecular forces? How is it related to the strength of intermolecular forces?
Surface tension is the tendency of liquids to minimize their surface area. Molecules at the surface have relatively fewer neighbors with which to interact because there are no molecules above the surface. Consequently, molecules at the surface are inheren
What is viscosity? How does viscosity depend on intermolecular forces? What other factors affect viscosity?
Viscosity is the resistance of a liquid to flow. Viscosity is measured in a unit called poise (P), defined as 1g/cm(s). The centipoise (cP) is a convenient unit because the viscosity of water at room temperature is approximately one centipoise.
Viscosity
What us capillary action? How does it depend on the relative strengths of adhesive and cohesive forces?
Capillary action is the ability of a liquid to flow against gravity up a narrow tube. Capillary action results from a combination of two forces: the attraction between molecules in a liquid, called cohesive forces, and the attraction between these molecul
Explain what happens when in the process of vaporization and condensation. Why does the rate of vaporization increase with increasing temperature and surface area?
Molecules are in constant motion, the higher the temperature the greater the average energy of the collection of molecules. However, at any one time, some molecules will have more thermal energy than the average and some will have less. The molecules with
Why is vaporization endothermic? Why is condensation exothermic?
The molecules that leave the liquid are at the high end of the energy curve- the most energetic. If no additional heat enters the liquid, the average of the entire collection of molecules goes down. So vaporization is an endothermic process; it takes ener
How is the volatility of a substance related to the intermolecular forces present within the substance?
The weaker the intermolecular forces are, the more likely molecules will evaporate at a given temperature, making the liquid more volatile.
What is the heat of vaporization for a liquid and why is it useful?
The heat of vaporization (change in H vap) is the amount of heat required to vaporize 1 mole of a liquid to a gas. The heat of vaporization of a liquid can be used to calculate the amount of heat energy required to vaporize a given mass of the liquid (or
Explain the process of dynamic equilibrium. How id dynamic equilibrium related to vapor pressure?
Molecules are in constant motion. Molecules leave liquid for the gas phase and gas phase molecules condense to become a liquid. Dynamic equilibrium has been reached when the rate of condensation and the rate of vaporization become equal. Although condensa
What happens to a system in dynamic equilibrium when it is disturbed in some way?
When a system in dynamic equilibrium is distributed, the system responds so as to minimize the disturbance and return to a state of equilibrium.
How is vapor pressure related to temperature? What happens to the vapor pressure of a substance when the temperature is increased? Decreased?
The vapor pressure of a liquid increases with increasing temperature. However, the relationship is not linear; it is exponential. As the temperature of a liquid increases, the vapor increases more and more quickly. As the temperature is decreased, the vap
Define the terms boiling point and normal boiling point.
The boiling point of a liquid is the temp. at which its vapor pressure equals the external pressure. The normal boiling point of a liquid is the temperature at which it s vapor pressure equals 1 atm.