uworld review

Question 1

combustion is what kind of process

Answer 1

a chemical process

Question 2

combustion is a CHEMICAL process through which the CHEMICAL energy stored in the

Answer 2

reactants’ molecular bonds is released by creating new bonds w/ less energy

Question 3

energy released from combustion is transformed into

Answer 3

thermal and kinetic energy

Question 4

in a combustion engine, chemical energy is….

Answer 4

converted to thermal and kinetic energy

Question 5

what are a broad class of lipids that are comprised of isoprene units?

Answer 5

terpes

Question 6

terpenes are

Answer 6

natural lipid products dervied from the five-carbon isoprene unit building block

Question 7

features of terpenes

Answer 7

total number of carbons in multiples of 5

carbon skeleton that reflects scaffold of an isoprene unit

Question 8

isoprenes are composed of

Answer 8

four carbon linear chain with a one-carbon branch

Question 9

covalent sigma bonds are made by

Answer 9

sharing electrons through end-to-end overlap of atomic orbitals

Question 10

length of a sigma bond can be estimated as the

Answer 10

sum of the atomic radii of the bonded atoms

Question 11

atomic radii tend to decrease

Answer 11

across a row

Question 12

atomic radii increase

Answer 12

down a column on the PT

Question 13

metal-nonmetal bonds tend to be

Answer 13

IONIC

Question 14

nonmetal-nonmetal bonds tend to be

Answer 14

COVALENT

Question 15

atoms with a large difference in electronegativity form

Answer 15

IONIC BONDS (usually metal + nonmetal)

Question 16

atoms with a small difference in electronegativity form

Answer 16

covalent bonds (two nonmetals)

Question 17

high-performance liquid chromatography (HPLC) does what?

Answer 17

separates molecules according to relative polarity and the resulting diff interactions w/ mobile + stationary phases

Question 18

in reversed-phase HPLC, mobile phase and stationary phase are what

Answer 18

mobile - polar solvent

stationary - nonpolar material

Question 19

HPLC is a technique where

Answer 19

liquid solvent (mobile) is under pressure and carries a sample sample through column filled with adsorbent material (stationary) to a detector

Question 20

extraction is a technique that uses

Answer 20

an organic solvent and an aqueous solution to separate molecules based on solubility

Question 21

sodium cations neutralize DNA’s charge via

Answer 21

ionic bonding with phosphate groups, making DNA less hydrophilic

allowing DNA to precipitate more efficiently

Question 22

more H-bonding sites =

Answer 22

greater affinity for stationary phase

Question 23

longest retention time elutes

Answer 23

LAST

Question 24

in normal HPLC, the stationary phase is

Answer 24

polar relative to the mobile phase

Question 25

molecules with more polar bonds have a

Answer 25

stronger affinity for the stationary phase have longer retention times

Question 26

exothermic reactions release or consume heat

Answer 26

RELEASE negative enthalpy

Question 27

endothermic reactions release or consume heat

Answer 27

CONSUME positive enthalpy

Question 28

protein aggregation released or consumes heat?

Answer 28

RELEASES HEAT EXOTHERMIC NEGATIVE ENTHALPY

Question 29

effect of nonvolatile solutes on BP in an unpurified protein sample

Answer 29

LOWER vapor pressure HIGHER boiling point

Question 30

protein unfolding consumes or releases heat?

Answer 30

CONSUMES HEAT ENDOTHERMIC POS ENTHALPY

Question 31

effect of nonvolatile solutes on BP in an purified protein sample

Answer 31

HIGHER vapor pressure LOWER boiling point

Question 32

keto-enol tautomerization is a

Answer 32

base or acid-catalyzed isomerization that converts a ketone or aldehyde into an enol

Question 33

tautomerization involves a proton transfer from the...

Answer 33

alpha-carbon of a ketone or aldehyde to the carbonyl oxygen along w/ pi bond migration

Question 34

capacitance is directly proportional to

Answer 34

capacitor plate area and inversely proportional to the distance b/w plates

Question 35

for resistors in parallel, the voltage drop...

Answer 35

across each resistor is IDENTICAL

Question 36

for resistors in series, the current

Answer 36

passing through each resistor is identical

Question 37

conductivity describes the ease with which

Answer 37

electric current flows through a material

Question 38

conductivity of metals may be attributed to the

Answer 38

loosely associated valence electrons within a metal

Question 39

conductivity of electrolytic solutions is directly proportional to

Answer 39

the molar concentration of charged ions

Question 40

oxidation and reduction always occur

Answer 40

together in a redox rxn

Question 41

when an atom is reduced by gaining 1 or more electrons, it's oxidized or reduced?

Answer 41

oxidized

Question 42

oxidation number is

Answer 42

calculated for each atom in a compounds relative to the number of electrons attached to element when neutral

Question 43

oxidation numbers may be assessed using

Answer 43

lewis structures

Question 44

entropy is the

Answer 44

increased number of possible arrangements leading to disorder

Question 45

entropy of solids

Answer 45

lowest of 3 common phases

Question 46

liquids have more/less entropy than solids

Answer 46

more

Question 47

entropy of gases

Answer 47

highest of 3 common phases

Question 48

during deposition, a substance in the gas phase transitions to

Answer 48

the solid phase greatest decrease in entropy

Question 49

sublimation is the process of going from

Answer 49

solid to gas largest increase in entropy