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lab exam - GAS LAWS Ideal gas law Molecules in the gas...

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GAS LAWS Ideal gas law – Molecules in the gas phase exert no forces on one another between collisions; PV=nRT, P=pressure, V=volume, n=mole, R=gas constant (0.0821), T=temperature Boyles Law = relationship between the pressure and volume of a confined gas; Boyle's law states that the volume of a fixed amount of gas is inversely proportional to pressure at a constant temperature. Boyle’s Law: P1V1= P2V2 Charles’Law: V1/T1= V2/T2 Avogadro’s Law: V1/n1= V2/n2 Gay-Lussac’s Law: P1/T1= P2/T2 INTERMOLECULAR FORCES Intermolecular forces are involved when molecules associate with one another in the liquid or solid states. Intermolecular forces include ion-dipole interactions, dipole-dipole interactions, and induced-dipole interactions. Since the compounds used in this experiment are covalent, no ion-dipole interactions are involved. Dipole-dipole interactions are weaker than ionic interactions and arise from interactions between partial charges. Hydrogen bonding is a particular type of dipole-dipole interaction that involves a link between the highly electronegative N, O, and F atoms and an electropositive H atom (which is bonded to a N, O, or F). Many molecular interactions involve induced dipoles (dispersion forces). As two nonpolar molecules approach one another, repulsions and/or attractions between their electrons and nuclei lead to distortions in their electron clouds. These slight distortions result in momentarily induced dipoles that lead to intermolecular attraction. Generally, a larger molecule (with more electrons) produces greater fluctuation in charge distribution and thereby a larger induced dipole. Dispersion forces generally increase with molecular weight. Dispersion forces are also affected by the arrangement in 3-D space of the atoms in a molecule. Unbranched (or straight chain) compounds tend to have stronger dispersion forces than their branched isomers. The atoms of neighboring branched molecules are unable to position themselves as close together as their unbranched 11—2 counterparts. When compared to hydrogen bonding, typical bond energies for dispersion forces are considerably lower and typically near 2 kJ/mol. The strength of these forces, however, lies in the cumulative effect of the large number of interactions possible as molecular complexity increases. KE = ½ mv(squared). In any sample of a gas or liquid, some molecules have very low energies, others have very high energies, but most have some intermediate energy, as described by the Maxwell- Boltzmann Distribution. Based on this distribution of kinetic energies, temperature is defined as the average kinetic energy of the system. This definition implies that all liquid or gas samples at the same temperature will have the same average kinetic energy. Vaporization is the conversion of a substance from the liquid state to the gaseous state. Any of the
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lab exam - GAS LAWS Ideal gas law Molecules in the gas...

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