Exam 2 Flashcards
Define intermolecular forces?
Forces of attraction that occurs between atoms, molecules, and ions due to their proximity to each other. These are weaker than intramolecular forces (covalent, ionic).
Why may intermolecular forces appear stronger than intramolecular forces?
Because of the large number of interactions.
What affects the strength of attraction between intermolecular forces?
- Magnitude of charge (real or partial)
- Distance between atoms
The stronger the attractive forces, the more they resist breaking apart.
What is surface tension?
A liquids resistance to its surface area. Liquids form spherical drops to minimize their surface area.
What is capillary action?
The spontaneous rising of liquid in a narrow tube as the result of cohesive (hold liquid molecules together) and adhesive forces (attract outer molecules to the container).
What is viscosity?
A liquids resistance to flow measured by the amount of energy necessary to move an object through a fluid.
How do phase changes involve intermolecular forces?
Disruption of molecular interactions by energy leads to changes in state of matter. Chemical bonds are not broken.
How does solubility relate to intermolecular forces?
Solubility depends on attractive forces of the solute and solvent. “Like dissolves like”.
Describe the weakest intermolecular force?
Van der waals (London dispersion) forces: arise from formation of induced dipoles between two nonpolar molecules
List the intermolecular forces from weakest to strongest?
Van der waals, dipole-dipole, hydrogen bonding, ion-dipole, electrostatic
Describe dipole-dipole interactions?
Occurs in all polar molecules. Strength depends on the nature of individual dipoles.
Describe hydrogen bonding?
Very strong specialized dipole-dipole interaction. Strongest when N, O, and F involved.
What are electrostatic interactions?
Ionic interactions between a cationic and anionic portion. Effective at distances further away and persist longer.
What is a solution?
A homogenous mixture of 2 or more substances
What is a solvent?
Major component of the mixture
What is a solute?
Minority component of the mixture
Which substance is water soluble and which is fat soluble?
Vitamin C is very water soluble to due to multiple polar groups (-OH, C=O)
Vitamin E is fat soluble because there is only two polar group and many C-H bonds
How is molecular weight calculated?
Multiply the number of atoms of each atom by their molar mass, then add all of the elements masses together to obtain the molar mass
How do you determine molarity?
Molarity is moles of solute / L of solution
How do you calculate weight percent?
mass solute / mass solution x 100
Solution will be given as (w/w).
Assume the percentage is out of 100 g sample.
How do you calculate volume percent?
volume solute / volume solution x 100
Solution will be given as (v/v).
Assume a 100 mL sample.
What does the root mean squared (RMS) equation tell us?
That at any given temperature, the average kinetic energy of molecules is the same.
If a gas has low molar mass, it will have a greater speed than one with a higher molar mass
What is Boyle’s law?
The pressure of a gas is inversely related to its volume when temperature is constant
What is Charles’ law?
The temperature of a gas is dirtectly related to the volume
If temperature increases, the volume increases
What is Gay-Lussac’s law?
The pressure exerted by a gas is directly related to the temperature of the gas
If temperature of a gas decreases so does the pressure.
What is the combined gas law?
Uses Boyle’s, Charles’, and Gay-Lussac’s law where n is constant.
What is Avagadros law?
The volume of a gas is directly related to the number or moles of the gas
If moles increase, volume increases
At STP 1 mol of gas occupies 22.4 L
What is Dalton’s law?
If two gases do not react are combined in a container, they act as if they are alone
The total pressure = sum of pressure of the individual gases
