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Jessie's MCAT Flashcards > Chem/Phys > Flashcards

Chem/Phys Flashcards

1
Q

What does horizontal center of mass mean?

A

Center of mass with respect to the x-axis. Conceptualize. Center of mass can be with respect to overall, horizontal or vertical.

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2
Q

Which quantum number describes the spatial orientation of a specific orbital within a given electronic subshell?

A

M(l), magnetic quantum number

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3
Q

What can the static friction coefficient of a unmoving object on a ramp be?

A

Remember that when an object is at a standstill, coefficient of static friction can be larger than the force trying to oppose the static friction.

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4
Q

If a block is moving down an incline with friction, how does the gravity of block component parallel to motion compare to force of kinetic friction?

A

When a block is sliding down a ramp w/ friction. Gravity on block is exerting a parallel-to-ramp force that is matching kinetic friction. If block is “sliding” assume they’re equal. Don’t assume you’re not given enough information to solve the problem.

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5
Q

What is Bond-Line structure?

A

Bond-line structure (bond-line formula, skeletal structure, skeletal formula): A representation of molecular structure in which covalent bonds are represented with one line for each level of bond order.

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6
Q

What is the order of priority for parent chain naming?

A

1) Carboxylic Acid
2) Sulfonic Acid
3) Ester
4) Acid Halide
5) Amide
6) Nitrile
7) Aldehyde
8) Ketone
9) Alcohol
10) Thiol
11) Amine

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7
Q

Is a resonance hybrid a resonance structure?

A

No, a Resonance hybrid is a compound, molecule, ion, or radical exhibiting resonance and having a structure represented in the written form as the average of two or more structural formulas separated each from the next by a double-headed arrow.

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8
Q

What are the properties of a structure that releases the least energy? (context: acids)

A

A structure exhibiting complete conjugation and resonance, which makes it more stable, means it will release the least energy.

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9
Q

What makes an acid stable?

A

what makes a strong acid is conjugation and resonance

stronger acids -> more stable conjugate bases | So from least acidic to most acidic, the order is amine < alcohol < phenol < carboxylic acid |

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10
Q

What does tert-butyl look like?

A

See image.

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11
Q

Do ramps change the work done on an object by pushing it up the incline?

A

Ramp incline does NOT change the amount of work done. Ramps only provide a mechanical advantage in that less force can be used because the smaller force will be applied over a greater distance.

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12
Q

What are the types of Potential Energy?

A

Chemical, Elastic, Mechanical, Electric

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13
Q

What is a Constitutional isomer?

A

Constitutional or structural isomers are compounds with the same molecular formula but different structural formulas.

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14
Q

What are the nucleobases and their structures?

A

See image.

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15
Q

How do the nucleobases bond?

A

See image.

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16
Q

How does stereochemistry across an alkene work? (E/Z vs cis/trans)

A

See image below. Highest atomic # or longest hydrocarbon chain wins priority for E/Z determination.

Cis/trans nomenclature is effective only when the alkene has two different groups on each carbon atom of the double bond and each carbon has one of the same group.

E/Z is used when all four groups are different

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17
Q

What is the most stable conformation for the ring structure?

A

When bulky substituents are equatorial-facing in opposite up/down directions.

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18
Q

What is the least to most energetically stable conformation for Newman projections?

A

The anti conformation, with both methyl groups oriented parallel and opposite at 180° apart, is the most energetically favorable and stable, followed by the gauche conformation with the two methyl groups 60° apart. Both the anti and gauche conformations are staggered, while the two remaining less favorable conformations are eclipsed and are transition states between gauche and anti. Of these two less stable eclipsed conformers, the conformer with overlapping methyls is the least favorable of all because of steric strain.

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19
Q

What are characteristics (3) of Enantiomers?

A

Non-superimposable, Mirror images and Same connectivity

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20
Q

What are ways (3) to separate Enantiomers?

A

Interactions with a chiral ligand, Chiral chromatography and Forming salts with other chiral compounds

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21
Q

What type of stereochemistry is this?

A

Meso. Achiral. Don’t fall for this trap. Be paranoid.

Meso compounds DO NOT have enantiomers. They DO have diastereomers.

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22
Q

Is this compound chiral?

A

Yes.

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23
Q

What is the equation for specific rotation?

A

In this equation, α (Greek letter “alpha”) is the measured rotation in degrees, l is the path length in decimeters, c is the concentration in g/mL

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24
Q

Is this a meso compound?

A

Yes. Has internal symmetry across middle w/ Chlorine.

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25
Q

What is the difference between a pyranose and a furanose?

A

A pyranose is a five-membered ring whereas a furanose is a six-membered ring.

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26
Q

When converting a carbohydrate Linear structure to a Haworth structure, what direction does carbon 3 point?

A

Left means Up and Right means Down when converting positiong of hydroxyl (-OH group) from Fischer to Haworth

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27
Q

Which of these carbons is the location of the hemiketal?

A

Carbon 4 is the location of the hemiketal. A hemiketal is a carbon bound to two -R groups, an -OR, and an -OH. The general structure of a hemiketal is shown below.

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28
Q

Which carbon represents the carbonyl carbon from the open-chain form? Which carbon represents the nucleophile from the cyclization reaction?

A

The C1 carbon does represent the carbonyl carbon from the open-chain form of ribose, and the hydroxyl attached to C4 is the nucleophile from the nucleophilic addition reaction.

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29
Q

What makes an anomeric carbon alpha?

A

The alpha anomer on a Haworth structure features a hydroxyl group oriented down trans to the CH2OH.

The anomeric carbon (the only carbon bonded to two oxygens) in this Haworth projection features a hydroxyl group oriented down opposite (trans) to the CH2OH group, making this molecule alpha. This is alpha-galactopyranose.

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30
Q

What is the difference between a hemiacetal and a hemiketal?

A

Hemiacetal has one R-group directly bonded to the anomeric carbon whereas the Hemiketal has two R-groups directly bonded to the anomeric carbon.

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31
Q

What direction will carbon 5 point in the Haworth projection form of this sugar?

A

The hydroxyl group on carbon 5 attacks the carbonyl group. The oxygen from this hydroxyl group becomes a member of the ring, so it is neither above nor below the ring in the Haworth projection of the sugar.

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32
Q

What is the difference between Conductivity, Resistivity, Conductance and Resistance?

A

Conductivity and resistivity depend on material properties of an object, while conductance and resistance also depend on the length and cross section surface area of an object (which make it easier and harder for an electron to move through an object, respectively).

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33
Q

What is the difference between Gravitational Potential and Gravitational Potential Energy?

A

Electric potential energy is similar to gravitational potential energy, in that both are the amount of stored energy for a total amount of mass/charge. Electric potential, on the other hand, is normalized to per unit charge and has units of joules per charge, or volts.

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34
Q

What is the difference between Electric Force and Electric Potential on Equipotential Field Lines?

A

Equipotential lines indicate locations in an electric field where the electric potential is constant, but not necessarily the strength of the electric field. If the strength of the electric field is not constant, then the strength of electric force it will exert on a charge is not constant either.

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35
Q

How do Conductivity and Resistivity affect flow of electrons?

A

A greater conductivity means that a material has a greater ability to allow for the flow of electrons. Conductivity is signified by the Greek letter sigma, or σ.

Resistivity is the property of a material which determines how well an object resists the flow of electrons. It is signified by the Greek letter rho, or ρ.

ρ = 1/σ and σ = 1/ρ

Conductivity is the inverse of resistivity, and conductance is the inverse of resistance. Conductivity and resistivity depend on material properties of an object, while conductance and resistance also depend on the length and cross section surface area of an object (which make it harder and easier for an electron to move through an object, respectively).

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36
Q

How are Gravity and Electricity similar concepts (2)?

A

The strength of an electric or gravitational field increases linearly with charge and mass, respectively.

Two masses will exert a gravitational force on one another. Likewise, two charges will exert an electric force on one another.

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37
Q

What are the units of Electric Force?

A

J/C

The units of force are newtons. Newtons times meters equals joules – therefore, joules divided by meters is an appropriate unit to describe force.

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38
Q

What are the units of Electric Potential Energy?

A

J

Electric potential energy describes a change in energy of an object as it moves through an electric field, described by joules.

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39
Q

What are the units of Electric Potential?

A

J/C

Electric potential is the amount of energy per unit of charge needed to move a charged object through a field. This can be described by joules per coulomb.

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40
Q

What are the units of Electric Field?

A

N/C

Electric fields extend outwards from an electric charge. The value for electric field will tell you how many newtons of force the electric field will exert on an object per unit of charge, at some point in that field.

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41
Q

What is the order of the following compounds in terms of most acidic to least?

Thiols, Carboxylic Acids, Ketones, and Alcohols

A

Propanoic acid > propanethiol > propanol > propanone

(from most acidic to least acidic)

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42
Q

Can you convert cyclohexanol into a carboxylic acid?

A

No, secondary alcohols can only oxidize into ketones.

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43
Q

What type of oxidizing agent is pyridinium chlorochromate classified as?

A

PCC is a Weak oxidizing agent

which means it can only oxidize a primary alcohol or secondary alcohol once to a ketone and not twice into a carboxylic acid.

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44
Q

Where does water rank in terms of acidity in comparison to an alcohola and a carboxylic acid?

A

Least to most acidic: ethane, ethanol, water, ethanoic acid

Carboxylic acids typically have pKa values anywhere in the 2-5 range

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45
Q

How can esters be created?

A

Esters can be created by reacting a carboxylic acid or carboxylic acid derivateive with an alcohol.

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46
Q

What is the order of these attractive forces from weakest to strongest?

Ionic bonds, london dispersion forces, hydrogen bonds, covalent bonds

A

london dispersion forces, hydrogen bonds, covalent bonds, ionic bonds

(weakest to strongest)

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47
Q

What are the magnetic spin orientations of diamagnetic, ferromagnetic and paramagnetic materials?

A

Diamagnetic atoms have no magnetic spin whatsoever.

Ferromagnetic materials contain atoms with uniform and non-random spin.

Paramagnetic materials contain atoms with random/non-uniform magnetic spins. (The only time the magnetic spins of paramagnetic atoms are purposefully aligned with one another is when an external magnetic field is applied to them.)

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48
Q

Can you tell the difference between paramagnetic and ferromagnetic material in the same magnetic field?

A

No, they will both have the same “induced” direction so it is not possible to tell them apart.

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49
Q

What are the properties required for a magnetic field to exert a force on an object?

A

Mass, charge and velocity

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50
Q

How would you order the following compounds by decreasing boiling point?

Alcohol, Aldehyde, Alkane, Carboxylic Acid

A

Carboxylic acid > Alcohol > Aldehyde > Alkane

The boiling point of a liquid increases as intermolecular forces increase and more energy is required to separate molecules. Carboxylic acids have the strongest intermolecular forces, because they form two hydrogen bonds per molecule via their CO2H; next is pentanol, which can hydrogen bond using its OH; then pentanal, an aldehyde with dipole-dipole interactions due to its polar C=O; and finally pentane, a simple alkane which has only London dispersion forces (Van der Waal’s forces). Thus, the boiling points will follow the same order.

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51
Q

What atoms does the negative charge shift between in an enolate?

A

Carbanion and Carbonyl Oxygen

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52
Q

Is the conjugate base of benzaldehyde acidic?

A

Benzaldehyde does not have any alpha protons on the carbon atom adjacent to the carbonyl carbon to deprotonate.

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53
Q

Which part of an enolate is the electrophile and nucleophile?

A

The alpha carbon of the enolate acts as a nucleophile while the carbonyl carbon of the neutral aldehyde would act as an electrophile when an aldehyde is in a solution with a strong base.

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54
Q

Which has a higher oxidation state, butanol or butanal?

A

Butanal has a higher oxidation state than butanol.

As a carbon gains bonds to oxygen, its level of oxidation increases. The carbonyl carbon of butanoic acid has three bonds to oxygen; the carbonyl carbon of butanal has two; the alcohol-bearing carbon of butanol has one; and butane has zero carbon-oxygen bonds.

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55
Q

What is the difference between Resistivity and Resistance?

A

Resisitivity is a property inherent to a material. It is resistance that changes with shape, not resistivity.

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56
Q

How would you order the particles of the phases in order of decreasing randomness?

A

gas, liquid, amorphous solid and crystalline solid

(decreasing randomness)

57
Q

Is surface tension affected by liquid density?

A

Yes.

Surface tension is the tension created at the liquid’s surface by the intermolecular forces between molecules, not the intramolecular forces.

Surface tension represents the amount of energy required to increase the surface area of a liquid. Since liquid density affects the liquid’s weight and surface area, it would also then affect surface tension.

58
Q

Are Kelvin/Celsius usage interchangeable with the heat capacity equation?

A

Yes since T is delta T.

Q = mc∆T

In this equation, c is the specific heat capacity of a substance, which is the amount of heat required to raise the temperature of one unit mass of substance by one degree. The SI units for specific heat capacity are J/g·K or J/g·°C. For example, the specific heat capacity of water is 4.186 J/g°C.

59
Q

How do you calculate heat necessary to transition 100g of water on heating curve?

A
60
Q

What’s the difference between surface tension and viscosity?

A

Viscosity is the property of liquids by which they are resistant to flow, or the resistance to deformation by shear stress. On the molecular level, viscosity is caused by friction between layers of the fluid that are in motion relative to each other. Thus, fluids that have higher viscosity are more resistant to flow than those with lower viscosity. Since olive oil is more viscous than whole milk, beaker A will be emptied first.

Surface tension is not a property of a liquid’s resistance to flow. Surface tension could be defined as the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the molecules’ intermolecular forces.

61
Q

Why is the conjugate base of any given acid a better nucleophile than the acid itself?

A

Any conjugate base will fulfill the Lewis acid definition of a base, that of being an electron donor. This overlaps completely with the function of a nucleophile - all Lewis bases are also nucleophiles.

62
Q

What atoms in the structure could be expected to act a a nucleophile?

A

An oxygen of a carboxylate and the nitrogen of an amine

The nitrogen atom in non-quaternary amines has a single lone pair.

Each oxygen of a carboxylate functional group has up to three lone pairs, meaning that these atoms could serve as nucleophiles.

63
Q

What is a suitable solvent for an SN2 reaction?

A

A polar aprotic solvent

64
Q

What are the conditions for an E2 reaction to happen?

A

E2 reactions require strong bases. SN2 reactions require good nucleophiles. Therefore a good nucleophile that is a weak base will favor SN2 while a weak nucleophile that is a strong base will favor E2. Bulky nucleophiles have a hard time getting to the α-carbon, and thus increase the proportion of E2 to SN2.

65
Q

What type of reaction is the cyclization of an aldohexose?

A

Cyclization of an aldohexose (or ketohexose, through an intermediate tautomerization step) is an example of an intramolecular nucleophilic addition mechanism.

66
Q

What types of molecular geometries favor nucleophilic addition to a carbon?

A

Nucleophilic addition requires that no leaving roup be displaced in the reaction. Both trigonal planar and linear molecular geometries allow for the replacement of one bond without loss of any substituents. Carbonyl carbons are the most common case of an electrophilic site with a trigonal planar geometry, while the carbon center of a nitrile is the most common case of an electrophilic site with a linear molecular geometry. Any nucleophilic attack on a carbon with a tetrahedral molecular geometry (commonly by the SN2 mechanism) would result in nucleophilic substitution, as carbon cannot form five simultanous bonds.

67
Q

What are the common types of Nucleophilic Addition reactions?

A

Common types of Nucleophilic Addition reactions include: Acid-catalyzed Hemiacetal Formation, Base-catalyzed Hemiacetal Formation and Monosaccharide Cyclization.

68
Q

What are the reactants and solvent for an Acid-catalyzed Hemiacetal Formation reaction?

A

Acid-catalyzed Hemiacetal Formation is done with an aldehyde and an alcohol in the presence of an acid solvent.

69
Q

What can prevent the mutarotation between anomers of any given ketose/hexose?

A

Nothing can prevent the mutarotation/interconversion of the anomeric forms of ketoses and hexoses because the nucleophilic addition towards a a trigonal planar carbonyl group may come from above or below the plane: If the attack comes from above the plane, the remaining hydroxyl must be facing the opposite way, and the alpha anomer (down-axial OH substituent) is formed. If the attack comes from below the plane, the remaining hydroxyl must again face the opposite way, and the beta anomer (up equatorial OH substituent) is formed.

70
Q

Are glycosidic bond formation considered types of nucleophilic substitution reactions?

A

Yes.

There are different types of glycosidic bond formation mechanisms which are all types of nucleophilic substitutions. There is N-glycosidic bond formation, named after the nitrogen nucleophile. O-glycosidic bond formation involved in the formation of sugars. Finally, S-glycosidic bond formation is also biologically very relevant in attaching sugars to cysteine residues.

71
Q

What is the Zeroth Law of Thermodynamics?

A

Zeroth law

If two objects are in thermal equilibrium, and another object is in thermal equilibrium with one of the objects, it will also be in thermal equilibrium with the third object; if TA = TB and TA = TC, then TB = TC

72
Q

What is the First Law of Thermodynamics?

A

First law

Energy cannot be created or destroyed; ΔU = Q - W

73
Q

What is the Second Law of Thermodynamics?

A

Second law

At absolute zero, entropy in a perfect crystal is 0; STemp=0 = 0

74
Q

What is the Third Law of Thermodynamics?

A

Third law

The disorder or entropy of the universe is always increasing; ΔSuniverse = ΔSsystem + ΔSsurroundings ≥ 0

75
Q

What is the equation for work in terms of volume and pressure?

A

Work is equal to pressure times the change in volume. In this case, the change in volume is 0 and thus the amount of work performed is 0. To think about it another way, imagine a pressure volume curve depicting this process. It would be a straight vertical line, meaning it would enclose no area.

76
Q

How do you change the sign of W (work) in the equation for the First Law of Thermodynamics to accomodate work done BY or ON the environment?

A

When work is done by the system on the environment then the work must be negative, when work is done on the system then work must be positive. Depending on the given equation of ΔU = Q - W, W must be changed to accomodate the former sign conditions.

77
Q

What phase of matter is compressible?

A

Only gases are compressible

78
Q

What is Boyle’s Law?

A

Boyle’s law relates the volume and pressure of a gas as follows: P1V1 = P2V2.

79
Q

What is Graham’s Law of Effusion?

A

R1/R2 = sqrt(M2/M1)

80
Q

What are the properties of an ideal gas?

A

The most ideal gases are those that experience the weakest intermolecular forces. HCl and CH4 have the least polar bonds of the gases listed and thus will exert the weakest attractive forces on other molecules.

81
Q

What is the equation for Specific Heat Capacity?

A

Q = mc∆T

In this equation, c is the specific heat capacity of a substance, which is the amount of heat required to raise the temperature of one unit mass of substance by one degree. The SI units for specific heat capacity are J/g·K or J/g·°C. For example, the specific heat capacity of water is 4.186 J/g°C.

82
Q

What does Heat Capacity have to do with?

A

Heat Capacity has nothing to do with intermolecular bonding forces.

A high heat capacity means it takes more energy to change the temperature of that substance. Large bodies of water like the ocean are useful for soaking up extra heat energy without experiencing a drastic change in temperature and conversely can give off large amounts of heat for an extended period of time when the environment is colder. This creates a stabilizing effect on temperature fluctuations in coastal environments.

83
Q

What are the concepts (3) that influence enthalpy?

A

The concepts that influence enthalpy are: thermal energy, pressure and volume

The formal definition of enthalpy is that it’s equal to the internal energy of a given system, plus the product of its pressure and volume. This is the same thing as saying that enthalpy is equal to the energy required to create the system, plus the work required to maintain its pressure and its volume.

84
Q

How do you calculate the Enthalpy Change of a reaction?

A

ΔH°f rxn = ΔH° (bonds broken) - ΔH° (bonds formed)

85
Q

Is the activation energy step of a Spontaneous reaction Endergonic?

A

A decrease in Gibbs free energy, or negative Gibbs free energy change, is associated with spontaneous reactions. These are also called EXERGONIC reactions, as the prefix “ex” tells us that Gibbs free energy is lost or decreases. On the other hand, if the products are higher in energy than the reactants, the reaction is less likely to proceed, so a positive Gibbs free energy change is associated with nonspontaneous reactions, also called ENDERGONIC reactions. For the reaction to take place, an energy barrier termed the activation energy must be overcome. This would be the endergonic, energy consuming step, of what is overall a spontaneous, exergonic reaction.

86
Q

Does the reaction mechanism and stability of the transition state dictate the reaction rate?

A

The reaction rate is dictated by the height of the activation barrier. The activation barrier is so high because it represents the transition state, a temporary configuration that’s very unstable and high in energy, and this is the state that the reactant molecules must transition through to become product molecules. The height of the barrier is dependent on the mechanisms and steps of the reaction, and the stability of those reaction intermediates. It will determine how quickly the reaction will proceed. For example, more stable intermediates mean a lower activation barrier and a faster reaction.

87
Q

What is the alternate form of Gibb’s Free Energy in terms of Keq?

A

ΔG = -RTln(Keq)

88
Q

What is the relationship between Keq and Q?

A

While the equilibrium constant Keq is used only at equilibrium, Q (the reaction quotient) may be used for reactant and product concentrations at any point in the reaction. When Q is greater than Keq, the relative proportions of products to reactants is higher than it would like to be at equilibrium, so the reaction will want to proceed in reverse from products toward reactants to achieve equilibrium. The question stem asks us to identify a reaction that will shift towards the reactants, meaning it will run in the reverse direction. Therefore, any reaction where Q > Keq will run in reverse to create more reactants.

89
Q

What is the equation for a square parallel plate capacitor?

A

C = A/d

90
Q

Is the Transition state stable and long-lasting?

A

No, the transition state is transient by definition; it will not be stable and long lasting.

91
Q

If you have two reactants, one is zero order and the other is second order, what is the rate-limiting step?

A

When the concentration of a reactant doesn’t change the rate but another does, the other rate will be the rate-limiting step regardless of it’s order.

92
Q

What factors can affect Gibbs Free Energy?

A

The free energy change under any set of conditions is the sum of the standard free energy change and RTlnQ, where R is the gas constant, T is absolute temperature and Q represents the reaction quotient ( a ratio of product concentration to reactant concentration, raised to their respective stoichiometric powers).

93
Q

For any reversible chemical reaction which reaction type will have the highest activation energy? (Endergonic or Exergonic)

A

Endergonic

95
Q

What type of reaction is ATP hydrolysis?

A

Exergonic, Spontaneous, Energetically Favorable, Pushes Reactions Forward

96
Q

How does Temperature affect the equilibrium of a reaction?

A

Not possible to know unless you know if Temperature is a reactant or product in the reaction.

97
Q

What defines an adequate buffer solution?

A

An adequate buffer solution should contain a weak acid and a similar (though not necessarily equal) molar amount of its conjugate base.

98
Q

What is the Henderson Hasselbalch equation?

A

The molecules acetic acid and acetate, when present in solution in near equimolar amounts, will produce a buffer system. The pH of a buffer solution can be calculated using the Henderson Hasselbalch equation:

pH = pKa + log([Base]/[Acid])

99
Q

How do you determine the pKa of an ideal buffer?

A

The pKa of an ideal buffer should be exactly at the pH that you are interested in buffering at, but pKa’s within a narrow range around the desired pH (e.g. +/- 1) are still acceptable.

100
Q

Where does the color change of a titration happen?

A

The color change does not occur exactly at the equivalence point, it merely approximates it.

The endpoint of a solution occurs where the color of the solution changes due to the weak acid/base indicator present. When choosing the indicator to use for a titration, you want to choose an indicator that changes color at a pH that is as close as possible to the pH at the equivalence point.

101
Q

What is the pH of a weak acid and strong base titration?

A

This pH must be greater than 7

Hydrofluoric acid is a weak acid, while sodium hydroxide is a strong base. Essentially, then, this question describes a weak acid/strong base titration. HF and NaOH react in a 1:1 ratio, so since the student added equimolar amounts of HF and NaOH, the two species will fully neutralize each other. The “final pH” referenced by the question stem, then, must simply be the pH at the equivalence point of a weak acid/strong base titration.

102
Q

Would 1 M ammonium and 0.5 M NaOH make a buffer system?

A

An adequate buffer solution should contain a weak acid and a similar (though not necessarily equal) molar amount of its conjugate base. An equal volume of 0.5 M sodium hydroxide has half the molar amount of base that 1.0 M acid does. Therefore, 0.5 M NaOH would deprotonate half the NH4+ present, resulting in 0.5 M ammonium and 0.5 M ammonia. A solution composed of 0.5 M ammonium and 0.5 ammonia would make for an appropriate buffer system.

103
Q

How do we know when two objects in periodic motion are in sync?

A

Objects must share the same period, frequency and start time to be in sync

104
Q

What is the equation for period of a pendulum?

A
105
Q

What is the equation for period of a spring?

A
106
Q

How does frequency change as sound travels between mediums?

A

The frequency remains the same between mediums. The change in velocity is reflected in a change in wavelength. Since the frequency remains constant, the period also remains constant.

107
Q

How do you find the wavelength and harmonic of a string, single and double-open ended pipe?

A

Find the wavelength by using v = f*λ
Using the wavelength, we can find the number of harmonics by using λ=(2L)/n (string + double-open ended tube)
2=(4L)/n (odd only for open end on one side of tube)

108
Q

What are the two properties of a Concentration Cell?

A

The electrodes are made out of the same material. The oxidation and reduction reactions are not physically separated in a concentration cell – they occur in the same chamber.

109
Q

How do you use a reduction table to find the most spontaneous/non-sponteanous reaction?

A

For a redox reaction reagent equation, you need to have one reduction and one oxidation reaction. You cannot have both

110
Q

What sign is the cathode in an Electrolytic cell?

A

The cathode is negative in an electrolytic cell

111
Q

What is the relationship between Q and E and E° in the Nernst equation?

A

If Q > 3 under standard conditions, then E < E°.

112
Q

What is the Electroplating formula?

A
113
Q

What is Binding Energy?

A

Binding energy is the amount of energy required to separate a nucleus into its individual components.

A nucleus is stable because it has lower energy than its individual components. In order to break a nucleus apart into its components, you therefore need to input some amount of energy to account for this difference; this is what we call the binding energy.

114
Q

What is the equation for calculating wavelength of an object?

A

The wavelength of an object is calculated using the equation λ = h/mv. As Planck’s constant is 6.634 x 10-34, any object with a mass that is not also extremely tiny will result in a wavelength near zero. Values this small are not useful and so are rarely used to describe macroscopic objects.

115
Q

How does the photoelectric effect work?

A

Einstein’s experiment proceeded first with shooting high energy photons at a metal surface. Those photons then needed to contain enough energy to overcome the work function of the metal. If the work function is satisfied, any remaining energy from the incident photon was transferred to one of the metal atoms electrons, exciting it to a higher energy state. If sufficient energy was transferred to the electron, it was able to eject from the metal atom.

116
Q

What does the amu found on the period table reflect?

A

The atomic mass unit (amu) of an element listed on the periodic table of elements is representative of the weighted average of neutrons found in the various elemental isotopes + the number of protons in that element.

117
Q

What can be said about the energy of the reactants and products of nuclear fusion?

A

The enormous energy released from a fusion reaction is explained by the observation that the product contains lower energy nuclear components compared to the original material.

In order for a fusion reaction to occur, massive amounts of energy must be used to force two atoms together into one. While this process takes a large amount of energy, it releases even more because the new atom is at a lower energy state than the original atoms added up individually. The energy released is referred to as the binding energy.

118
Q

What does Gamma Decay involve?

A

Gamma decay involves the emission of a gamma ray, or high-energy photon, from an excited nucleus. As a gamma ray is a photon, which is massless and has no charge, the atomic number and atomic weight of an atom does not change when it undergoes gamma decay.

119
Q

How does a semi-log plot of radioactive decay look?

A

The semi-log plot of radioactive decay transforms the exponential decay graph into a linear plot in which the y-axis is expressed logarithmically, while the x-axis remains unchanged (expressed as time).

120
Q

How is mass difference calculated?

A

The mass difference can be calculated by isolating m such that: m = E/c2

121
Q

What is the deBroglie equation?

A

Electrons behave like photons of light and have both particle- and wave-like properties. The de Broglie equation gives that the wavelength of an object is equal to Planck’s constant, h, divided by the mass of the object times its velocity: λ = h/mv. By rearranging the equation, it can be found that h = λmv.

122
Q

How does the Photoelectric Effect work?

A

The work function is the minimum amount of energy required to expel an electron from an atom. Therefore, work function only determines the threshold frequency that an incident photon must equal or exceed in order to expel an electron. The work function is directly proportional to the threshold frequency: Ework function = hfthreshold. The number of photons in a light beam corresponds to its intensity, while the energy per photon corresponds to its frequency. Additionally, the threshold frequency is a property of the material determined by its work function, not a property of the light beam. Though the terms may appear similar, light frequency describes the energy per photon, while light intensity describes the number of photons in the incident light.

123
Q

Why does absorption spectra of a solution change during a chemical reaction?

A

The absorption spectrum of a solution may change as a chemical reaction takes place because the products may absorb different wavelengths of light than the reactants due to differences in bonding patterns.

124
Q

What is the only thing that affects the speed of an electromagnetic wave?

A

The speed of an electromagnetic wave is also called the speed of light and is dependent only on the medium the wave is traveling in. EM waves travel fastest in a vacuum, and slower in any other medium.

125
Q

What changes when an electromagnetic wave enters a new medium that isn’t a vacuum?

A

Speed of light decreases and frequency does not change so wavelength must decrease.

We know that the frequency-wavelength relationship, c = fλ will be maintained. We also know that the frequency does not change as an EM wave enters a new medium: since no wave peaks are appearing out of thin air, however often a peak hits the interface from the first medium must be the same as how often peaks are passing into the second medium.. Therefore, the wavelength must change. Solving our previous equation, we can see that λ = c/f, or that wavelength is directly proportional to the speed of light in a medium. Therefore, since velocity decreased, so will the wavelength.

126
Q

What are the limitations of Spectrophotometry?

A

Limtations of spectrophotometry include:

Very concentrated solutions might absorb too much light to give an accurate reading.

The spectrophotometer must be calibrated to the wavelength the compound absorbs best.

The relationship between absorbance and concentration of a sample has to be known beforehand.

127
Q

Does light from the sun travel as fast as a radio wave?

A

Yes. All electromagnetic waves travel the same speed in a vacuum.

128
Q

What is the difference betwen a Preparative Purification and an Analytical Purification?

A

A preparative purification is employed when a researcher wishes to have a large amount of the desired protein, while an analytical purification is used when a researcher desires a small protein extract for qualitative analysis.

129
Q

What are the steps of Protein Purification?

A

Step 1) Cell membranes are lysed

Step 2) Proteins and other cell components are extracted

Step 3) Proteins are separated by centrifugation

Step 4) Unwanted proteins are precipitated out of solution

Step 5) The precipitate is removed by centrifugation or filtration

Step 6) Chromatography is used to isolate the protein of interest

Extract proteins and other cellular components from a biological sample, usually cultured cells or from a tissue sample. Unless the proteins are secreted by the cells into the surrounding solution, this must be done by mechanically lysing the cellular membranes. Cell membranes can be lysed by repeated cycles of freezing and thawing, mechanical agitation, sonication, treatment with organic solvents, or with a detergent that disrupts the integrity of the membrane.

Following cell lysis, there is an extract containing proteins, other biomolecules, membrane fragments, and various organelles. The next step is to separate proteins from other cellular components by centrifugation, which segregates particles in solution by mass, shape and density.

Another technique that’s sometimes used to separate out proteins is to alter their solubility by changing the salt concentration of their surroundings. This involves adding just enough salt to just below the salt concentration at which the target protein precipitates out of solution, thus precipitating only unwanted proteins out of solution. At this point, the precipitate can be removed by centrifugation or by filtration, passing the solution through a filter to remove insoluble products.

These steps alone are not very selective, however, so they are usually followed by some sort of chromatography to isolate the protein of interest.

130
Q

What is Western Blotting?

A

In western blotting, antibodies are applied that bind directly to a specific protein. This primary antibody may itself be tagged with a dye or fluorescent marker, or more commonly, a secondary antibody that recognizes and binds to the primary antibody will be tagged in order to visualize bands corresponding to the protein of interest following gel electrophoresis.

131
Q

What is Radioimmunoassay?

A

Another immunochemical technique is what’s known as a radioimmunoassay, in which the concentration of protein in a sample can be assessed indirectly by measuring the extent to which the unlabeled proteins in the sample compete with radioactively labeled antigens for antibody binding sites.

132
Q

What is ELISA?

A

Another important immunoassay is the enzyme-linked immunosorbent assay, or ELISA. With ELISA, the antigens in a sample are attached to a solid surface, normally on a plate. Antibodies specific to the antigen of interest are then applied to the plate, and these bind their protein antigens. After washing to remove unbound particles, the amount of bound antibody is determined by an enzymatic reaction that produces a visible signal, such as a color change, emission of fluorescence, or current that can be measured to quantify the amount of protein antigen present in the original sample. The enzymes catalyzing these reactions are linked to the antibodies.

133
Q

What is Spectroscopy?

A

Spectroscopy can also be used to quantify the amount of protein in a sample based on its absorption of light at a characteristic wavelength. In spectroscopy, light is transmitted through a sample, and the amount of light transmitted through the sample is detected by the spectrometer. This is used to produce an absorption spectrum with peaks of high absorption of light by the sample, corresponding to low transmittance of light through the sample. Protein concentration can then be calculated using the Beer-Lambert law.

134
Q

What types of waves can Sound be classified as?

A

Sound waves can be classified as:

longitudinal, compression and pressure (waves)

135
Q

How do you increase the speed of sound?

A

A material with a large bulk modulus is not compressible, which means sound waves have an easier time traveling through the medium.

136
Q

How do you calculate the Decibels (intensity) of a sound?

A

The equation for decibels is:
dB = 10 log (I/I0)

137
Q

What is the Doppler Equation?

A

f’ = f0 (vsound - vobserver / vsound + vsource)

138
Q

What are all the velocity signs corresponding to observer/source moving towards/away from the source/observer?

A

The observer is moving towards the source | positive vsource

The observer is moving away from the source | negative vobserver

The source is moving towards the observer | negative vsource

The source is moving away from the observer | positive vsource

139
Q

What are the variables involved in the Doppler Equation?

A

Speed, velocity and frequency are part of the Doppler equation

140
Q

When will the enol form predominate over the keto form in enolate chemistry?

A

When the enol form exhibits extended conjugation more than the keto form then the enol form is will predominate.

Jessie's MCAT Flashcards (4 decks)

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