genchem Flashcards
forces of attraction that exist between all atoms and molecules.
the only force present among nonpolar substances such as oxygen gas and carbon dioxide.
LONDON DISPERSION FORCES
these are attractive forces between molecules.
responsible for the non-ideal behavior of gases, but they exert more influence in the condensed phases of matter which are liquids and solids
INTERMOLECULAR FORCES
attractive forces between polar molecules, that is, between molecules that possess dipole moments.
the larger the dipole moment the larger the force.
DIPOLE-DIPOLE FORCES
It is a special case of very strong dipole-dipole interaction.
a result of interaction between partial positive atoms (H) and the partial negative such F, O, and N.
HYDROGEN BONDING
acts between an ion and a polar molecule.
the positive end of the ionic compound becomes surrounded by the partial positive ion.
ION-DIPOLE FORCES
LONDON DISPERSION FORCES, DIPOLE-DIPOLE FORCES, HYDROGEN BONDING, ION-DIPOLE FORCES
TYPES OF INTERMOLECULAR FORCES
LIQUIDS, SURFACE TENSION, CAPILLARY ACTION, VISCOSITY, VAPOR PRESSURE, Volatile, MOLAR HEAT OF VAPORIZATION, BOILING POINT
PROPERTIES OF LIQUIDS AND INTERMOLECULAR FORCES
are made up of particles that are close to each other and have kinetic energy.
take the shape of their container and diffuse moderately to a fixed volume.
most of them exist as molecules at room temperature.
LIQUIDS
is the force that causes the surface of a liquid to contract. It is the property of the surface of the liquid that allows it to resist an external force.
SURFACE TENSION
is the tendency of a liquid to rise in narrow tubes or be drawn into small openings such as those between grains of rock. is a result of intermolecular attraction between the liquid and solid materials.
CAPILLARY ACTION
is the intermolecular attraction between like molecules (the liquid molecules).
Cohesion
is an attraction between unlike molecules (such as those in water and in the particles that make up the glass tube).
Adhesion
is the resistance of fluids to flow. A liquid’s resistance (friction) to flow exists between the molecules of liquid when they move past each other. The greater the resistance in flowing, the more viscous the liquid is.
VISCOSITY
is a change of state from liquid to gas, while the opposite process (gas to liquid).
when liquid molecules break free from their neighbors and escape into gas phase, the process is called vaporization.
VAPOR PRESSURE
-substances that evaporate readily are _. eg, alcohol, gasoline, paint thinner and dry-cleaning solvents.
Volatile
the relationship between vapor pressure and the strength of intermolecular forces is consistent with the trends in two other properties of liquids, the enthalpy or molar heat of vaporization, and the boiling point of liquid.
MOLAR HEAT OF VAPORIZATION
the term solution is used to describe a homogeneous mixture in which at least one substance (solute) is dissolved in another substance (solvent).
Solution
the boiling point of liquid is the temperature at which the liquid converts into a gas.
a liquid boils when its vapor pressure equals the pressure acting on the surface of the liquid. The boiling point is the temperature at which the vapor pressure of a liquid is equal to the external pressure.
BOILING POINT
(also called percent by weight or weight percent) is the ratio of the mass of a solute to the mass of the solution, multiplied by 100 percent:
Percent by Mass
is a common expression used for expressing concentration. It is related to the molar concentration but the difference is that the ___ ___ is expressed with a denominator of 100
Percent by Volume
When the amount of solute is very small, as with trace impurities in water, concentration is often expressed in parts ___ ___
Percent per million
It is a dimensionless quantity that expresses the ratio of the number of moles of one component to the number of moles of all components present. For a mixture of two substances, A and B, the mole fractions of each would be written as follows
Mole Fraction
Otherwise known as “molar concentration”. It is defined as the number of moles of solute per liter of solution. The SI unit for molarity is mol/m3 ; however, you will almost always encounter molarity with the units of mol/L. A solution of concentration 1 mol/L is also denoted as “1 molar” (1 M). Mol/L can also be written in the following ways (however, mol/L, or simply M, is most common)
MOLARITY (M)
It is an intensive property of solutions, and it is calculated as the moles of a solute divided by the kilograms of the solvent. Molality is the number of moles of solute dissolved in 1 kg (1000 g) of solvent—that is, (The SI unit for molality is mol/kg.
MOLALITY (m)
