Practice Test Review (Chemical and Physical)

Question 1

How do you find molarity?

Answer 1

Find the total mass of the compound and divide by that compounds molar mass (g/mol), which is calculated via the periodic table

Question 2

What does absorption of salt in the blood cause?

Answer 2

The blood to become hypertonic, causing osmosis of water out of the cells

Question 3

What is alpha decay?

Answer 3

An alpha particle (two protons, two neutrons, 2+ charge) is emitted

Question 4

What is beta-minus decay?

What is beta-plus decay?

Answer 4

Beta-plus: Proton is converted to a neutron, a beta+ particle (positron) is emitted.

Beta-minus: Neutron is converted into a proton, a beta- particle (electron) is emitted.

Question 5

What is gamma decay?

Answer 5

A gamma ray (high energy photon) is emitted from an excited nucleus.

Question 6

What is electron capture decay?

Answer 6

A nucleus “grab” an electron, which changes a proton into a neutron.

Question 7

What is a half-life?

Answer 7

Time required for one-half of the parent isotopes in a sample to decay into daughter isotopes

Question 8

General MCAT Tip:

Answer 8

When asked a specific question about research design or execution (not testing over knowledge), choose an answer that can be inferred from the text, rather than an obscure guess that makes sense

Question 9

What is chiral?

Answer 9

A carbon attached to four different groups.

Question 10

How do you find the amount of stereoisomers for a molecule?

Answer 10

2^n the amount of chiral centers

Question 11

What do l and d mean in terms of chirality?

Answer 11

Compounds that produce clockwise (+) rotation of light are dextrorotatory, compounds that produce counterclockwise (-) rotation of light are levorotatory

Question 12

What are boiling chips used for in distillations?

Answer 12

Provide nucleation sites that give the liquid a place to start forming bubbles to prevent superheating

Question 13

What is vacuum distillation used for in distillations?

Answer 13

Lower the boiling points of the substances to be distilled. (Reduces the atmospheric pressure)

Question 14

When does boiling occur?

Answer 14

What the vapor pressure of the substance equals the atmospheric pressure.

Question 15

In distillation procedures, which compound boils off first?

Answer 15

The one with the lower boiling point.

Question 16

How do you compare the boiling/melting point between two compounds?

Answer 16

Functional groups with hydrogen bonding have higher boiling/melting points. Nitrogen containing compounds have medium melting/boiling points.

Question 17

How do you determine formal charge?

Answer 17

valence electrons - sticks - dots.

Question 18

How do you determine the amount of valence electrons?

Answer 18

The main group number (Main groups are numbered 1 - 8, skipping over the transition metals)

Question 19

How do you calculate gravitational potential energy of a mass?

Answer 19

Mass * g * height

Question 20

How do you calculate kinetic energy of a mass?

Answer 20

1/2 Mass * velocity^2

Question 21

How do you calculate maximum speed achieved by a mass?

Answer 21

Set potential energy (Mass * g * height) = kinetic energy (1/2 Mass * velocity^2) and solve for velocity

Question 22

How do you find stereo centers?

Answer 22

Carbon bonding to four different substituents, may need to look several positions away from the stereo center to find a difference in substituents

Question 23

What is the preferred ion configuration of many elements determined by?

Answer 23

The electron configuration of the nearest noble gas; elements will gain or lose electrons until they have the same valence electron configuration as this noble gas

Question 24

What is the equation for torque?

Answer 24

T = rFsin(theta), F is force applied from the fulcrum, d is the distance between the force and the fulcrum, and theta is the angle between the lever arm and the force that is applied

(if the force is applied perpendicular to the rotation then sin(90) = 1)

Question 25

What is the equation for velocity?

Answer 25

distance/time

Question 26

What is a titration?

Answer 26

The process of finding the concentration of an unknown solution by reacting it with a solution of known concentration.

Question 27

What is the equivalence point of a titration curve? How can you find it on the titration curve?

Answer 27

When the Molarity base * Volume base = Molarity acid * Volume acid Halfway along the steep portion of the titration curve

Question 28

How do competitive inhibitors affect Vmax and Km? Noncompetitive? Uncompetitive?

Answer 28

Competitive- No change to Vmax (maximum velocity), but Km (concentration needed to reach half of Vmax) is increased. Noncompetitive- Vmax is decreased, Km stays the same. Uncompetitive- Vmax and Km are both decreased

Question 29

What is an IC50 value?

Answer 29

Half Maximal Inhibitory Concentration - represents the concentration of a drug that is required for 50% inhibition in vitro

Question 30

What are the unit prefixes milli, micro, nano, pico?

Answer 30

Milli: 10^-3 Micro: 10^-6 Nano: 10^-9 Pico: 10^-12

Question 31

What are the three Newton laws?

Answer 31

1st: An object remains at rest unless acted upon 2nd: Total sum of focus acting on an object is equal to mass*acceleration 3rd: When body A exerts a force on body B, body B exerts an equal an opposite force on body A

Question 32

How does N2 function as a gas? What is it used for?

Answer 32

It is very inert, can be used as a good artificial atmosphere when working with reactive reagents

Question 33

What is the makeup and structure of acetone?

Answer 33

C3H6O, trigonal planer with a =O and 2 -CH3

Question 34

How do you calculate total resistance from individual resistances?

Answer 34

1/Rtot = 1/R(one) + 1R(two) + ...

Question 35

What is Ohm's law, and what is the equation for power?

Answer 35

``` Voltage(V) = Current(I) * Resistance(R) Power(P) = Current(I) * Voltage(V) ```

Question 36

What are the three simple power equations?

Answer 36

P = IV, P = I^2R, P = V^2/R

Question 37

What is the reagent LiAlH4 used for?

Answer 37

reduction (gain of hydrogen or loss of oxygen or other electron withdrawing species)

Question 38

What is the reagent O3 used for?

Answer 38

Cleavage of alkenes

Question 39

What is the reagent H2 with Pd used for?

Answer 39

Very strong reduction to alkane

Question 40

What is the reagent KMnO4 used for?

Answer 40

Very strong oxidizing agent

Question 41

Molecules with names that end in -one, -en, or -ol are what?

Answer 41

steroids

Question 42

What are the three major functions of steroid hormones?

Answer 42

Salt, sex, and sugar

Question 43

``` Describe the 6 Primary enzyme classes: oxidoreductase transferase lyase hydrolase ligase ```

Answer 43

oxidoreductase- oxidation-education reactions transferase- group transfer lyase- break molecules into two smaller molecules without using water or redox reactions hydrolase-cleavage of a molecule using water ligase- two substrates are stitched together while giving off a water

Question 44

What do peaks at 3000 and 1700 indicate in IR spectroscopy?

Answer 44

3000 - OH | 1700 =O

Question 45

Which pair of amino acids creates disulfide linkages?

Answer 45

C-C (Cysteine)

Question 46

A light entering a more dense medium (index of refraction >1.00) will have what relationship between angel of incidence and angle of refraction?

Answer 46

Angle of refraction will be lower than angle of incidence

Question 47

When can total internal reflection result?

Answer 47

When a ray of light begins in a higher index material and reaches a boundary with a lower-index one (starts in water and moves towards air)

Question 48

How many valence electrons does a single bond represent for the central atom? Lone pair?

Answer 48

Single bond counts for one valence electron. Lone pair counts for two

Question 49

What does RSE stand for? What does it indicate?

Answer 49

Relative stabilization energy. The lower the value the greater the stabilization

Question 50

What is the relationship between deltaH, deltaS, and spontaneity?

Answer 50

DeltaH (-) + DeltaS (+) = always spontaneous DeltaH (+) + DeltaS (-) = never spontaneous DeltaH (-) + DeltaS (-) = spontaneous at low temperature DeltaH (-) + DeltaS (+) = spontaneous at high temperature

Question 51

What is a capacitor? Resistor? Battery/Galvanic cell?

Answer 51

Capacitor- Used to store charge Resistor- impedes charge Galvanic cell- uses a spontaneous redox reaction to produce an electrical potential

Question 52

What are the function of microtubules?

Answer 52

vesicle transport and organelle positioning, formation of spindle