Chem-Phys

Question 1

How do you add vectors geometrically?

Answer 1

Vector sum for path tracing involves taking the bottom of the second vector and putting it where the arrow of the first vector is, and then draw the connecting line

Question 2

What is chemical structure of acetylene?

Answer 2

Acetylene is another name for ethylene. It involves 2 carbons in a triple bond

Question 3

What is molecular orbital theory and how does it work?

Answer 3

MO theory looks at energy differences between molecular orbitals. When two atomic orbitals interact, there will always be 2 molecular orbitals that result. One energetically stabilized and the other destabilized anti-bonding interaction

Question 4

How does resonance affect hybridization?

Answer 4

If atom appears to exist in more than one hybridization state depending on the resonance structure drawn, the lowest possible hybridization state is always assigned

Question 5

What are the chemical formulas for: nitrous oxide, nitric oxide, nitrogen dioxide, and dinitrogen pentoxide

Answer 5

N2O: nitrous oxide; NO: nitric oxide; NO2: nitrogen dioxide, N2O5: dinitrogen pentoxide

Question 6

What is the relationship between altitude and atmospheric pressure?

Answer 6

Higher altitudes= lower atmospheric pressure

Question 7

What is the lowest value on the Kelvin scale?

Answer 7

Lowest value for kelvins is 0 K (absolute 0) which corresponds to -273C

Question 8

Once you find the amount of moles present in species, divide them by species’ coefficient in balanced reaction

Answer 8

-

Question 9

How do you calculate power (using current and voltage) and energy (from power and time?)

Answer 9

Power: IV, Energy: Power X Time

Question 10

What does polarization of light mean?

Answer 10

Light can be linearly polarized, which means it filters out any light rays that aren’t pointing in a certain direction

Question 11

What is the sign for power for a diverging lens?

Answer 11

Focal length of a diverging (concave) lens is negative, so power (1/f) is negative

Question 12

Which type of bond has highest melting point?

Answer 12

Ionic bonds have highest melting points

Question 13

When do gasses behave least ideally?

Answer 13

Gases deviate from ideal activity at low temperature and high pressure.

Question 14

What is a nonvolatile solute?

Answer 14

Nonvolatile solutes means it doesn’t produce vapor pressure in solution. It increases the boiling point

Question 15

What happens to K values when adding chemical reactions?

Answer 15

When adding chemical reactions, the associated equilibrium constants can be multiplied together to give the equilibrium constant for the overall reaction.

Question 16

How do you shield a magnetic field?

Answer 16

Magnetic fields (unlike electric fields which we can separate electric monopoles) can’t be blocked; all magnetic field lines must terminate on the opposite pole. Magnetic field lines can be rerouted. By surrounding an object with a material which can conduct magnetic flux better than materials around it, the magnetic field will flow along this material and avoid the objects inside

Question 17

What properties of a gas make it the least ideal?

Answer 17

Deviations from ideal gas behavior are maximized when molecular volume and/or intermolecular interactions are increased.

Question 18

Why are trans fats more dense than cis fats?

Answer 18

Trans fats are like saturated fats in that they stack close together, making them more dense than cis fats and thus more likely to be solids at room temperature

Question 19

What changes when light enters a new medium?

Answer 19

Upon entering a new medium (such as glass or air from space), the velocity and wavelength of light change (although the velocity of light in a vacuum is higher than in any other medium), while the frequency remains unaltered.

Question 20

What are Arhennius acids and bases?

Answer 20

Arhennius base increases concentration of OH- in solution, Arhennius acids increase concentration of H+ in solution

Question 21

What peak do amides produce in NMR?

Answer 21

Amides produce peaks around 5-8.5 ppm

Question 22

What happens to carboxylic acids at physiological conditions?

Answer 22

Carboxylic acids have pKa of <7, so at physiological conditions it will form anion

Question 23

What is a chaotropic agent?

Answer 23

” chaotropic agent is any molecule in aqueous solution that can disrupt the hydrogen bonding network including the bonds between water molecules. As such, these agents (urea is one example) are capable of denaturing proteins by disrupting the hydrogen bonds that stabilize their configurations.

Question 24

What is percent dissociation?

Answer 24

”"”percent dissociation.”” The percent dissociation of HF is simply the percent of the original acid concentration that has dissociated into H+ and F- ions. This value is equal to [H+]/[HF] x 100%.”

Question 25

How can you solve for velocity without time?

Answer 25

vf^2=vi^2+2ad

Question 26

What is a gamma particle?

Answer 26

A gamma particle is a photon of electromagnetic energy, which does not have mass

Question 27

What is an alpha particle?

Answer 27

An alpha particle consists of 2 protons and 2 neutrons, having a mass of 4 amu

Question 28

What is a beta particle?

Answer 28

A beta particle is the nuclear equivalent of an electron, which has the mass of approximately 1/1800 of a proton

Question 29

What is a positron?

Answer 29

A positron is the antiparticle of an electron and has its same mass

Question 30

How can more complete fractionation of proteins using size-exclusion chromatography be achieved?

Answer 30

Increasing the column length enhances the resolution of the column, leading to a more completion fraction by size-exclusion chromatography. This is because the material of the matrix provides the physical means of separating the proteins. If the proteins come in contact with a longer length of matrix, the differences in retarding forces experienced by the proteins will have a greater cumulative influence on the migration of the proteins, lengthening the differences in their retention times

Question 31

Strong acids, Strong bases

Answer 31

HCl, HBr, HI, H2SO4 (sulfuric acid), HNO3 (nitric acid), HClO4 (perchloric acid) NaOH, LiOH, KOH, CsOH

Question 32

How does SDS-Page work?

Answer 32

SDS-Page denatures proteins and applies a negative charge to the overall molecule, so it is separated by size