Chem/Phys

Question 1

Nuclear decay where a neutron is converted to a proton and an electron is emitted

Answer 1

B-minus Decay

Question 2

Is nuclear decay reversible and/or spontaneous

Answer 2

Not reversible but spontaneous

Question 3

In this decay, the atomic nucleus captures an electron, which causes a transformation of a proton to a neutron

Answer 3

Electron Capture

Question 4

A proton is transformed into a neutron and a positron (beta-plus particle) is emitted.

Answer 4

B+ decay

Question 5

do Isotopes have the same chemical properties?

Answer 5

Yes. They only differ in atomic mass(# of neutrons)

Question 6

malignant cells often undergo mutations that promote their own growth and the development of blood vessels to feed them. This process is termed?

Answer 6

(angiogenesis)

Question 7

Boiling Stones are used to

Answer 7

provide nucleation points for heated substances to form bubbles, therefore, preventing overheating.

When transitioning from liquid to gas during boiling, the liquid needs nucleation sites, or places to start forming bubbles. This is typically achieved either by scratching the inside of the flask or by introducing boiling chips.

Question 8

The vacuum in vacuum distillation serves the purpose of

Answer 8

lower boiling point by decreasing atmospheric pressure.

This is helpful when trying to boil liquids with very high bps.

Question 9

Amines (R–NH2, R–NHR’, or R-NR’R”), imines (R=NH or R=NR’), and enamines (C=C–NH2, C=C–NHR, or C=C–NRR’) are nitrogen-containing compounds with medium melting/boiling points that can act as weak bases. Sulfur-containing functional groups contain the root “thio” and generally act similarly to the corresponding oxygen-containing groups.

Answer 9

Reactivities

Question 10

Have to be careful when counting stereocenters.

Answer 10

Look out for non-represented hydrogens

Question 11

Torque Formula

Answer 11

Torque = rFsin(theta)

Question 12

Titration is the process of finding the concentration of an unknown solution (the analyte) by reacting it with a solution of known concentration (the titrant). The analyte is generally placed in an Erlenmeyer flask, while the titrant is placed in a burette so that the volume of solution added can be monitored. The titrant is added to the analyte until the endpoint is reached. Calculations are then performed to find the unknown concentration of the analyte. Titrations are typically performed for acid/base reactions but are not limited to them.

At equivalence points during the titration, the number of acid or base groups added to the solution is equivalent to the number of base/acid groups in the original unknown solution. We can calculate our unknown concentration or volume using the formula NaVa = NbVb, where N and V are the normality (mol/L) and volume of the acidic and basic solutions, respectively. It is important to convert from molarity (M) to normality (N) for polyprotic acids and polyvalent bases.

The flat regions of titration curves represent buffering solutions (a roughly equal mix of an acid/base and its conjugate), while the steep, near-vertical sections of the curve contain equivalence point(s), which indicate that enough of the titrant has been added to completely remove one equivalent (acid or base group) from each of the original molecules in the unknown solution. Species with multiple acid or base groups (e.g., H3PO4 or Ca(OH)2) will have multiple equivalence points during the titration.

The final key point of any titration is the endpoint. To be successful, there must be some method for observing the endpoint of the reaction. The type of titration reaction that is being used will determine the method used for observing the endpoint. For example, in an acid-base titration, a specific pH value will be the endpoint (monitored by color-changing indicators), while for precipitation reactions, the endpoint is realized by the appearance of a precipitate. Regardless of the details of the reaction involved, the goal of titrations is always to use known volumes/concentrations to determine unknown volumes/concentrations.

Answer 12

know it

Question 13

Titration of Analyte

Answer 13

In a titration, the analyte — the substance whose quantity or concentration is to be determined — is reacted with a carefully-controlled volume of standard solution, of which the concentration is known. When analyzing a titration curve, look for the equivalence point(s), which are located halfway along the steep portion(s) of the curve. For a monoprotic acid at the equivalence point, Mbase × Vbase = Macid × Vacid = moles acid.

Question 14

is the number of equivalents of reactive species per liter of solution, for which we must define the reactive species. Normality is often used to express the concentration of H+ or OH− ions produced in acid-base reactions. For example, hydrochloric acid (HCl) generates one equivalent of H+ ions and one equivalent of Cl− ions per mole, while sulfuric acid (H2SO4) generates two equivalents of H+ ions and one equivalent of SO42− ions per mole.

Answer 14

normality (N)

Question 15

Under what conditions are gases likely to act non-ideally?

Answer 15

Gases are more likely to behave non-ideally under extremely high pressures or at very low temperatures.

Question 16

3 bonded pairs and 1 lone pair (NH3). WHat VSPER SHAPE?

Answer 16

Trigonal pyramidal

Question 17

2 bonded pairs and 2 lone pairs

Answer 17

Bent V-shaped

Question 18

Difference between Molecular Shape and E.lectronic Geometry.

Answer 18

A distinction is sometimes made between molecular geometry, which only takes into account the shape formed by the actual bonds that an atom makes, and electronic geometry, which also takes into account lone pairs. Thus, we could say that NH3 has a tetrahedral electronic geometry but a trigonal pyramidal molecular geometry.

Question 19

Capacitors. What is the formula for charge stored in capacitor?

Answer 19

charge stored by a capacitor is a function of its capacitance and voltage, as expressed by the equation Q = VC. When capacitors are connected in series, their capacitance adds reciprocally, like how resistance adds for resistors in parallel. When capacitors are connected in parallel, their capacitance adds directly, like resistors in series

Question 20

Resistors Vs Capacitors

Answer 20

Resistors add reciprocally in parallel, but directly in series.
Capacitors add reciprocally in series, but directly in parallel circuits.

Question 21

Terpenes

Answer 21

(C5H8)n, units

Question 22

Monoterpene have how many isoprenes?

Answer 22

2 isoprene units make a monoterpene

Question 23

Two important oxidizing agents

Answer 23

1) PCC (pimary alcohol to aldehyde)

2) NaCrO2 (prima alc to carboxylic acid)

Question 24

how many fused rings do sterol derived biomolecules have?

Answer 24

Four (4)

Question 25

Places where steroid hormones are synthesized

Answer 25

adrenal cortex, gonads, mitochondrion, and smooth endo

Question 26

How many classes of enzymes are there?

Answer 26

There are six (6) primary classes of enzymes.
1- oxidoreductases
2- Lyases and isomerases (similar, not the same, both transfer charged groups.
3- ligases
4- Transferases
5- hydrolases

Question 27

The carbonyl stretching frequency falls in the range of

Answer 27

1700-1750

Question 28

Do diatomic molecules show IR peaks? why or why not?

Answer 28

No, because there are no vibrations or rotations since there is no net change in dipole moment. (N2, O2)

Question 29

Optics and snells law

What is total internal reflection

Answer 29

total internal reflection can only result when a ray of light begins in a higher-index material and reaches a boundary with a lower-index one (e.g. starting in water and moving towards air). Here, the light ray started in air (n = 1) and moved into water (n ∼ 1.3), making total internal reflection impossible.

An important special case occurs when light moves into a medium with a smaller index of refraction (that is, when n2 < n1). A classic example of this is when light is moving from water to air. As this happens, the angle θ with the normal will increase—in other words, the ray of light will bend further away from the normal. As the angle of the incident ray (θ1) increases, there will come a point where the angle of the refracted ray (θ2) reaches 90°. This is known as the critical angle. If we increase the angle beyond the critical angle, the light can no longer refract at all. Instead, all the light rays are reflected within the original medium. This is known as total internal reflection.

Question 30

Hybridization

Answer 30

the orbitals of an atom hybridize so that they are homogenous. For example, on paper, the central carbon in methane (CH4) has four valence electrons and would appear to have one s orbital and three p orbitals. In reality, however, these orbitals combine, or hybridize, to produce four identical sp3 orbitals. Hybridization between one s orbital and two p orbitals may also occur to produce three sp2 orbitals, or between one s orbital and one p orbital to produce two sp orbitals.

Question 31

Le Chatelier

Answer 31

For a reaction where ∆H > 0, increasing the temperature will shift the reaction toward the products, while decreasing it will shift the reaction toward the reactants; the opposite pattern is found if ∆H < 0.

Question 32

Key Distinction between Enthalpy and Entropy

Answer 32

In thermodynamics, a key distinction is made between enthalpy (heat energy in a system) and entropy (energy in a closed system that is unavailable to do work). The enthalpy (H) of a reaction is the heat energy it contains. The most important law when looking at enthalpy is Hess’s law: ΔHrxn = Σ∆Hproducts - ΣΔHreactants. This equation illustrates that enthalpy, like entropy, is a state function. This means that the ∆H accompanying a chemical reaction is independent of the mechanism by which the reaction occurs. That is, when reactants are converted into products, the overall enthalpy change is the same whether it is done as one step or multiple steps.

Question 33

Electron withdrawing groups. A note about fluorine

Answer 33

Being electronegative. Fluorine destabilizes a carbocation. It pulls electron density to further destabilize positive charge on carbocation

Question 34

capacitors

Answer 34

Circuits on the MCAT contain batteries, resistors, and/or capacitors. Capacitors have several medical applications (e.g. defibrillators) and are used to store charge and electrical potential energy, precluding the need for large batteries in electrical components. A basic capacitor consists of two metal plates separated by a layer of insulating material called a dielectric. Capacitance is the ability to store charge and is calculated as C = ɛ0A/d, where A is the area of the plates and d is the distance between them.

When two conducting plates are connected to a battery, electrons move towards one plate. The positive plate loses electrons as well, and both plates eventually have equal and opposite charge, +Q and −Q. When a capacitor is fully charged, the capacitor has charge Q. We can relate the charge, capacitance, and voltage across the plates using the equation Q = VC (remember the home shopping network?). The voltage in this equation is the maximum potential difference that can be applied before the insulation of the dielectric breaks down. The electrical potential energy stored in the capacitor can also be related via the equations E = ½ QV = ½ CV2. Once fully charged, the capacitor can discharge a current across the circuit until the capacitor is “emptied” of all the stored charge. The MCAT may ask you to compare the difference in terms of charging when a battery is connected (V is constant) or disconnected (Q is constant).

Finally, capacitors can be combined in series (common path) or in parallel (common origin and destination, different path). Capacitors in series combine like resistors in parallel (1/Ceq = 1/C1 + 1/C2…) while capacitors in parallel combine like resistors in series (Ceq = C1 + C2…).

Question 35

The ——— serves as the body’s “thermostat” to maintain body core temperature

Answer 35

Anterior Hypothalamus

Question 36

The body can lose heat by increasing cutaneous blood flow and sweating, or by decreasing the basal metabolic rate through thyroid signaling.

Answer 36

jj

Question 37

The body can gain heat by

Answer 37

reducing the cutaneous blood flow and increasing muscle activity (shivering)

Question 38

Used in the transport of vesicles and positioning of organelles in the cell.

Answer 38

Microtubules. structures are composed of dimers of the protein tubulin.

Question 39

structural vs enzymatic proteins. Which ones are more important?

Answer 39

Structural