MCAT chem/phys

Give the definition for enantiomers. What is there R/S configuration?

non-superimposable mirror images that canNOT appear identical with rotation.

• >1 chiral center

• NO internal plane of symmetry

• opposite R/S configuration

give the definition for diastereomers.

Non-super imposable MIRROR images, NOT mirror images

• >2 chiral centers

• some opposite and some same R/S configuration

what is the difference between constitutional isomers and steroisomers?

Consitutional isomers have DIFFERENT connectivity while stereoisomers have the same connectivity. Thye both have the same molecular formula.

What are the differences between diastereomers and enantiomers?

• Enantiomers are mirror images

• enantiomers have all opposite R/S configurations at chiral centers. diastereomers have some same, some different.

For Poiseuille’s Law give the relationship between flow rate and each of the variables (how do changes in each variable effect Q)

• Q is proportional to r^4 (double r= increase Q by 16x)

• Q=P, more pressure difference = more flow

• Q=1/viscosity (double viscosity = ½ flow)

• Q= 1/L (double length = ½ flow)

what is the difference between heat capacity and specific heat?

• heat capacity: the amount of heat required to raise the temperature of an object by 1 deg C

• specific heat: the amount of energy required to raise the temperature of 1 gram of the substance by 1 deg C

What is hyperopia and what causes it? Where is the original image? What lens is used to fix this and how does it work?

hyperopia = farsighted

• optical power is not sufficient → image is BEHIND retina

• tx w/ converging/convex lens → focal point shifted toward the retina

What is myopia and what causes it? Where is the original image? What lens is used to fix this and how does it work?

myopia = nearsighted

• focal point is in FRONT of retina

• tx with diverging/concave lens → shift image away from lens

converging/convex lenses create what type of image?

real and inverted

diverging/concave lenses create what type of image?

virtual and upright

what type of wave is light?

a transverse electromagnetic wave

what does it mean for a wave to be “transverse”?

the wave oscillates perpendicular to the direction of travel

give a one-sentence definition of polarization:

restricting in the electric field of a transverse wave to one direction (unpolarized light usually goes in many directions)

• one direction of oscillation

why can light waves be polarized but not sound waves?

sounds waves are longitudinal, light waves are transverse

what 2 fields make up light?

magnetic field (B) and electric field (E)

which field of light determine polarization?

E (electric) field

what does a linear polarization filter do to light?

allows for transmission of electromagnetic radiation whose E field is parallel to the axis of polarization.

• inhibits passage of radation whose E field is perpendicular to this axis

what happens to the intensity (I) of unpolarized light if it passes through ONE polarizer?

Intensity becomes ½ of its original

what happens if light hits 2 polarizers at 90 degrees?

NO light passes

what does polarization ALWAYS refer to?

direction of E field

In normal TLC the stationary phase is ______ and the mobile phase is _______

stationary: polar (silical gel, alumina)

mobile phase: nonpolar (hexanes, ethyl acetate)

In normal TLC:

nonpolar compounds will react more strongly with the stationary/mobile phase and procees closer to/farther from the solvent front.

polar compounds will react more strongly with the stationary/mobile phase and proceed closer to/farther from the solvent front.

• nonpolar compounds react more w/ the mobile phase because it is nonpolar (like dissolves like) and therefore proceeds closer to the solvent front.

• polar compounds react more w/ the stationary phase because it is polar and therefore be farther from the solvent front

which types of compounds (polar/nonpolar) will have a larger Rf in TLC?

nonpolar, because they interact more with the nonpolar mobile phase and move farther down the plate towards the solvent front