Polymer" is a generic term used to describe a very long molecule consisting of structural units and repeating units connected by covalent chemical bonds.
A key feature that distinguishes polymers from other molecules is the repetition of many identical, similar, or complementary molecular subunits in these chains.
These subunits, the monomers, are small molecules of low to moderate molecular weight, and are linked to each other during a chemical reaction called polymerization.
Polymer
Author: asim /
Chemical compound
Author: asim /
A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition.
The ratio of each element is usually expressed by chemical formula.
For example, water (H2O) is a compound consisting of two hydrogen atoms bonded to an oxygen atom. The atoms within a compound can be held together by a variety of interactions, ranging from covalent bonds to electrostatic forces in ionic bonds.
Real Gases
Author: asim /
Deviate at least slightly from Ideal Gas Law because of two factors:
gas molecules attract one another
gas molecules occupy a finite volume
Both of these factors are neglected in the Ideal Gas law. Both increase in importance when molecules are close together (high P, low T)
van der Walls equation corrects for the attraction between molecules.nb corrects for the volume of gas moleculesvan der Walls constants are given
gas molecules attract one another
gas molecules occupy a finite volume
Both of these factors are neglected in the Ideal Gas law. Both increase in importance when molecules are close together (high P, low T)
van der Walls equation corrects for the attraction between molecules.nb corrects for the volume of gas moleculesvan der Walls constants are given
Kinetic Theory of Gases
Author: asim /
Three postulates of the Kinetic Theory
1.Gases consist of particles (atoms or molecules) in continuous, random motion.
2.Collisions between gas particles are elastic.
3.The average energy of translational motion of a gas particle is directly proportional to temperature. In addition to the postulates above, it is assumed that the volumes of the particles are negligible as compared to container volume and attractive forces between particles are neglected.
Et = average kinetic energy of translationKEavgm = mass of the particleu = average velocity of the particle
from the third postulate we can formulateT = temperature in Kelvin, c = constant which has the same value for all gases.
A.Average Speed of Gas particles (find u)c = constant = R = gas constant, NA = Avogadro's #substituting for cmass times moles (NA) equals Molar Mass (MM), substituting MM and solving for u givesusing this last equation we can solve for an individual gas particle's speed rms = root mean square, which is the average square root of the speed of the individual particles.Use R = 8.3148 , in order for the units to come out in m/s
B.Grahm's Law
effusion - the flow of gas particles through a small opening or pinhole in a container.diffusion - random motion of gas particles.formulas:if the two gases are at the same temperature then:
Experimentally usually measure the time for effusion to occur, this time is an inverse of the effusion rate (lower times-faster effusion rates)
this equation was used for the separation of U238 during WWII by effusion principles.
1.Gases consist of particles (atoms or molecules) in continuous, random motion.
2.Collisions between gas particles are elastic.
3.The average energy of translational motion of a gas particle is directly proportional to temperature. In addition to the postulates above, it is assumed that the volumes of the particles are negligible as compared to container volume and attractive forces between particles are neglected.
Et = average kinetic energy of translationKEavgm = mass of the particleu = average velocity of the particle
from the third postulate we can formulateT = temperature in Kelvin, c = constant which has the same value for all gases.
A.Average Speed of Gas particles (find u)c = constant = R = gas constant, NA = Avogadro's #substituting for cmass times moles (NA) equals Molar Mass (MM), substituting MM and solving for u givesusing this last equation we can solve for an individual gas particle's speed rms = root mean square, which is the average square root of the speed of the individual particles.Use R = 8.3148 , in order for the units to come out in m/s
B.Grahm's Law
effusion - the flow of gas particles through a small opening or pinhole in a container.diffusion - random motion of gas particles.formulas:if the two gases are at the same temperature then:
Experimentally usually measure the time for effusion to occur, this time is an inverse of the effusion rate (lower times-faster effusion rates)
this equation was used for the separation of U238 during WWII by effusion principles.
The Ideal Gas Law
Author: asim /
Variables:
V=
volume (liters, cubic decimeters, milliliters, cubic centimeters).
n=
amount in moles, n = (MM = molar mass from Periodic Table).
T=
temperature, for gases must be in Kelvin, K = oC = 273.15, usually find temperature to nearest degree, so only add 273.
P=
pressure (atmospheres, millimeters of mercury, kilopascals, torr. 1 atm = 760 mm Hg = 101.3 kPa = 760 torr = 29.92 in Hg = 14.7 lb/in2, these are all at 0 oCtorr named after Torricelli - Italian scientist, first person to accurately measure atmospheric pressure, 1640
Calculation of Gas Pressure
barometer - closed manometer, take h directly.
manometer - open manometer.Pgas = Patm + P due to h mm Hg H2O is on the atmospheric side in the h part of the equation, this will effectively give the addition or subtraction from atmospheric pressure.
Relation between variables;
PV=nRTwhere R is a true constant, it is the same for all gases and is independent of P, V, n or T.
inputting standard temperature and pressure (STP) for any gas will give the same R, Avogadro's Law - the same number of particles at the same P, T, and V.
V=
volume (liters, cubic decimeters, milliliters, cubic centimeters).
n=
amount in moles, n = (MM = molar mass from Periodic Table).
T=
temperature, for gases must be in Kelvin, K = oC = 273.15, usually find temperature to nearest degree, so only add 273.
P=
pressure (atmospheres, millimeters of mercury, kilopascals, torr. 1 atm = 760 mm Hg = 101.3 kPa = 760 torr = 29.92 in Hg = 14.7 lb/in2, these are all at 0 oCtorr named after Torricelli - Italian scientist, first person to accurately measure atmospheric pressure, 1640
Calculation of Gas Pressure
barometer - closed manometer, take h directly.
manometer - open manometer.Pgas = Patm + P due to h mm Hg H2O is on the atmospheric side in the h part of the equation, this will effectively give the addition or subtraction from atmospheric pressure.
Relation between variables;
PV=nRTwhere R is a true constant, it is the same for all gases and is independent of P, V, n or T.
inputting standard temperature and pressure (STP) for any gas will give the same R, Avogadro's Law - the same number of particles at the same P, T, and V.
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