Chem/Phys - Unknown Exam Qs

Question 1

Phosphoryl transfer of kinases comes from which phosphate of ATP

Answer 1

Gamma-phosphate

Question 2

Henderson Hasselbalch Equation

Answer 2

pH = pKa + log([base]/[acid])

Question 3

Out of the bonds listed, which is the shortest: C-H, C-O, C-C, C-N

Answer 3

C-H

Question 4

Molar volume of an ideal gas at STP

Answer 4

22.4 L/mol

Question 5

Power = ?

[units?]

Answer 5

P = ΔW/t = ΔE/t = PE/time = mgh/t
P = F*v (force*velocity)

Circuits: P = VI (Voltage*current) = I^(2)R = V^(2)/R
* Power dissipated by a resistor or supplied by battery *

[Watts] = [J/s] = [Nm/s] = [kgm^(2)/s^(3)]

Question 6

Work = ?

[units?]

Answer 6

W = Fd = Fdcos(theta)
W = ΔKE or W = - ΔPE = mgΔh (work done by force of gravity) 
W = P*t (Power * time)

Spring:W = - ΔPE(elastic) = 1/2kx^(2) } k = spring constant [N*m]

THERMO: W = Q(heat)- ΔE(change in systems internal energy)
W = PΔV (Pressure* ΔVolume)

E field: W = - ΔPE(Elec) = ΔVq (change in E potentialcharge)
Battery/capacitor: W = QV (total charge *voltage)

[J] = [Nm] = [kgm^(2)/s^(2)]

Question 7

What is the Osmotic pressure of 0.3 M NaCl(aq) at 7°C?

Answer 7

π = iMRT = 2 * 0.3 [M] * 0.0821 [Latm/molK] * 280 [K]
-> π = 13.8 atm

NaCl -> Na+ + Cl- } 2 molar ions -> i = 2 (vant hoff factor)

Question 8

12 volt battery delivers 10 Amps of current for 10 seconds. What is the work done by the battery? and power?

Answer 8

Current: I = Q/t
-> Q = I * t = 10 A * 10 s = 100 C
Work = Q * V = 100 C * 12 V = 1200 J

Power: P = I * V = 10 A * 12 V = 120 Watts (J/s)
So another way to get work: W = P * t = 120 J/s * 10 s = 1200 J

Question 9

What type of image is formed from a diverging lens if the object is situated at a distance larger than the focal length?

Answer 9

Diverging lenses: neg. focal length -> form virtual and reduced images of objects situated at distances larger than the focal length

Question 10

Triaglycerols consist of…

Answer 10

Traiglycerols = neutral storage lipids; consist of 3 fatty acids ester-linked to single glycerol

Question 11

Coordinate-covalent bond

Answer 11

Lewis acid/base interaction btwn metal cation and electron pair donor

Question 12

Conversion that takes place in a battery-powered resistive circuit when current is flowing

Answer 12

Chemical to Electrical to Thermal
- Chemical energy of the battery element is used as electrical energy to set charge carriers in motion through the resistor, where they experience drag from the crystal lattice of the resistive conductor and dissipate their energy as heat from the resistor

Question 13

Protein secondary structure is characterized by …

Answer 13

Repeated patterns of hydrogen bonds between backbone amide protons and carbonyl oxygen atoms

Question 14

The relative thermodynamic stability of isomeric organic compounds can be inferred from what type of experimental data?

Answer 14

Heats of combustion -> the relative thermodynamic stability of isomers can be determined based on the amount of heat produced when the compounds are combusted;
- less heat = greater stability

Question 15

Suppose that a blood vessel of cross-sectional areaAcarries microbubbles at a speedvinto a capillary bed. If the capillary bed is made up ofncapillaries, each with cross-sectional areaa, with what speed will the blood flow in the capillary bed?

Answer 15

according to the continuity equation, ifuis the speed of flow in the capillary bed, thenA×v=n×a×u, sou=A×v/(n×a)

Question 16

FAD is a cofactor ____

Answer 16

Oxidant

Question 17

• Necessary experimental conditions to achieve reliable data for M-M enzyme kinetics:

Answer 17

• Initial velocity is measured under steady state conditions.
• Solution pH remains constant at all substrate concentrations.
• The concentration of enzyme is lower than that of substrate.

Question 18

Heme cofactor

Answer 18

porphyrin:basic unit of a porphyrin is the pyrrole ring, a five-sided heterocycle containing one nitrogen atom

Question 19

Resistivity is the inverse of _____

Answer 19

Conductivity

Question 20

How does ΔG′° relate to Keq?

Answer 20

• ΔG′° = −RTlnKeq

Question 21

cation-exchange column only binds to _____ charged proteins, which only occurs when the pH is ____ than the pI.

Answer 21

cation-exchange column only binds to positively charged proteins, which only occurs when the pH is less than the pI.

Question 22

A common column material used in size-exclusion chromatography is dextran, a polysaccharide of glucose. Which type of interaction most likely occurs between proteins and the dextran column material?

Answer 22

H-bonding -> because a polysaccharide of glucose has numerous hydroxyl groups that can hydrogen bond to polar side chains that are typically exposed on a protein surface

Question 23

When ultrasound wave passes into human tissue, the _____ of the wave remains unchanged because it is not affected by the medium through which it propagates

Answer 23

Frequency;

in contrast to wave speed, amplitude, and wavelength

Question 24

how are temperature, resistance, and current in a conductor related?

Answer 24

I ~ 1/R ~ 1/T

R ~ T

Question 25

Does a precipitate form when Ksp is greater than or less than the concentration of reactants?

Answer 25

Ksp < [X][Y] -> precipitate forms

Question 26

Rank ions by size: potassium, chloride, and sodium

Answer 26

Na+ < K+ < Cl-

Question 27

IR range for: 
C=C
C=O
O-H
N-H
CCOOH (carboxylic acid)

Answer 27

C=C: 1580 - 1610 cm^(-1)
C=O: 1700 - 1750 cm^(-1) -> sharp peak
O-H: 3200 - 3500 cm^(-1) -> broad peak 
N-H: 3300 cm^(-1) -> sharp peak
CCOOH (carboxylic acid): broad peak at 3000 cm^(-1) & 1750 cm^(-1)

Question 28

H-NMR spectroscopy - Chemical shift (ppm) of:

• sp3 carbon
• sp carbon
• sp2 carbon
• aromatic carbon
• aldehyde
• carboxylic acid
• TMS (standard)

Answer 28

• sp3 carbon: 0 - 2
• sp carbon: 2 - 3
• sp2 carbon: 3 - 6
• aromatic carbon: 6 - 9
• aldehyde: 9 - 10
• carboxylic acid: 10 - 13
• TMS (standard): 0

Question 29

Isolate polypeptides and proteins from aqueous extracts via freeze drying (separation/purification method) -> aqueous solution of the polypeptide or protein is frozen.
How would you remove water from the frozen sample?

Answer 29

Remove water from the frozen sample via sublimation under reduced pressure (keeps mixture cold and maintains proteins native state)

Question 30

Acetal and cyanohydrin (HCN) functional groups will ____ in H2SO4(aq).

Answer 30

Hydrolyze

Question 31

How can you calculate the density of the human body from its weight in air and its weight while submerged in water?

Answer 31

density of human body is proportional to Wair/(Wair - Wwater)

• according to Archimedes principle, density of an object divided by density of fluid object is submerged in is equal to the ratio of the weakest of the object in air over the difference in submerged weight and weight in air.