ETS Major Field Test - Chemistry

isomers are two compounds with the same molecular formula that are different

what are isomers

1. Structural (constitutional) isomers

2. Stereoisomers (two types) - enantiomers and diasteromers

3. Geometric isomers (also known as cis and trans isomers)

What are the three types of isomers?

different bonding arrangement of atoms. atoms are bonded together in a different sequence

what is a structural (constitutional) isomer?

stereoisomers: atoms are bonded together in the same sequence, but have different 3-D arrangement in space

enantiomers: non-superimposable mirror images

diasteromers: stereoisomers that are not enantiomers: not superimposable and not mirror images

what is a stereoisomer? what are the two types of stereoisomers?

an atom that has four different groups attached to it

what is a chiral atom?

-R configuration - clockwise

-S configuration - counterclockwise

If a chiral atoms is in the "R" configuration, in what direction does the arc go?

if a chiral atom is in the "S" configuration, in what direction does the arc go?

at least 2

how many chiral centers does a diastereomer need to have?

the larger the molecular weight, the lower the water solubility

how does molecular weight relate to water-solubility?

-increases water solubility

-alcohols, amines, C=O, ethers, and F

-How does the presence of hydrogen-bonding change the water-solubility?

-What can hydrogen-bond with water?

The more linear, the less water soluble, due to a greater non-polar surface area than a branched molecule of the same molecular weight

What shape of a molecule can make a substance less water-soluble and why

the larger the molecular weight, the higher the boiling point.

How does molecular weight relate to boiling point?

The more linear, the higher boiling point, due to a greater surface area than a branched molecule of the same molecular weight.The more surface area, the more chances for van der Waals attractions.

what shape of a molecule can make a molecule have a higher boiling point and why?

The presence of hydrogen-bonding increases boiling point dramatically.Alcohols, 1 and 2 amines and amides, and carboxylic acids all hydrogen-bond with other molecules of themselves.Dipole-dipole attractions between C=O's increase boiling point to a lesser extent.

How does the presence of hydrogen-bonding change the boiling point?

NMR tells us how many different types of hydrogens or carbons there are in a compound

What does Nuclear Magnetic Resonance (NMR) Spectrometry tell us?

tells us about what type of atom it is and what it is bonded to

What does the position of the peak in NMR tell us

the time taken for a particular compound to travel through the columns to the detector

what is retention time

result from limitations in the equipment or techniques used to make a measurement

what is random error

energy required to remove the outermost electron from a gaseous atom

what is ionization energy

-Acid = proton donor

-Base = proton acceptor

What is a Bronsted acid? What is a Bronsted base?

-acid = accepts a pair of electrons to form a new covalent bond

-base = donates a pair of electrons to form a new covalent bond

What is a lewis acid? what is a lewis base?

trigonal bypyramidal

what is the molecular geometry of PF5

square planar

what is the molecular geometry of XeF4

square pyramidal

what is the molecular geometry of BrF5

tetrahedral

what is the molecular geometry of CH4

octahedral

what is the molecular geometry of SF6

bent

what is the molecular geometry of H2O

T-shaped

what is the molecular geometry of CIF3

linear

what is the molecular geometry of CO

linear

what is the molecular geometry of BeF2

completely ionized in aqueous solution - LiOH, NaOH, KOH, Ca(OH)2, Ba(OH)2

What is a strong base? Examples

-Ionization energy DECREASES as you go DOWN a group

-Ionization energy INCREASES as you go ACROSS a period

what are the ionization energy trends on the periodic table

-cyclic

-one p orbital on each atom

-Planar (allowing for overlap)

-Have 4, 8, 12, 16....pi electrons

-Especially unstable

what does a compound need to be anti aromatic

energy is conserved; it can be neither created nor destroyed

-the internal energy of an isolated system is constant

what is the first law of thermodynamics

in an isolated system, natural processes are spontaneous when they lead to an increase in disorder, or entropy

-the entropy of an isolated system tends to increase

what is the second law of thermodynamics

the entropy of a perfect crystal is zero when the temperature of the crystal is equal to absolute zero

-the entropies of all perfectly crystalline substances are the same at T=0

what is the third law of thermodynamics

when a subsystem at equilibrium is subjected to a disturbance, the composition of the system adjusts so as to tend to minimize the effect of the disturbance

what is Le Chatlier's principle

no

does the presence of a catalyst change the equilibrium constant of a reaction

-temp raised = exothermic reaction favoring the reactants

-temp lowered = endothermic reaction favoring products

What does Le Chatelier's principle say about the effect of temperature

when a system is compresses, the composition of a gas-phase equilibrium adjusts so as to reduce the number of molecules in the gas phase

What does Le Chatelier's principle say about the effect of compression

sp hybrids

what type of orbital does a linear structure have

sp2

what type of hybrid orbital does a trigonal structure have

sp3

what type of orbital does a tetrahedral structure have

can be caused by an imperfection in the equipment being used or from mistakes the individual makes while taking the measurement

what is systematic error

defined as being the energy required to remove the outermost electron from a gaseous atom

what is ionization energy

completely ionized in aqueous solution - HCl, HBr, HI, HNO3, HClO4, H2SO4

what is a strong acid? examples

if system A is in thermal equilibrium with system B, and system B is in thermal equilibrium with system C then system A and C are also in thermal equilibrium

the zeroth law of thermodynamics

Second law states that the entropy of the universe will increase for any spontaneous process. when water freezes in a freezer, it is a spontaneous process and its entropy decreases. the freezer is pumping heat into the surroundings, thus the entropy of the surroundings is increasing. this increase in entropy in the surroundings is greater than the decrease in entropy in the water/ice

deltaA and ice - if entropy increases in a spontaneous process why does water freeze spontaneously at temperatures below 0C

the slower the reaction occurs, the greater the kinetic stability

kinetic stability

the lower the overall energy, the more thermodynamically stable

thermodynamic stability

does not affect the rate

0th order - concentration is linear with time - how do changes in concentration affect the rate?

direction relationship - doubling the concentration doubles the rate - all radioactivity decay is first order

1st order - the natural log of the concentration is linear with time - how do changes in concentration affect the rate

doubling the concentration quadruples the rate of the reaction; if you half the concentration you cut the rate by 1/4

2nd order - the reciprocal of the concentration is linear with time - how do changes in concentration affect the rate

half life is constant for first order reactions, and each subsequent half-life twice as long as the previous for 2nd order reactions

half-life equations - for which order is the half-life constant - for which order is each subsequent half-life twice as long as the previous?

when both 4s and 3d orbital's are empty, the 4s is lower in energy because s orbitals have a nonzero probability of being right next to the nucleus

Potassium's electron configuration - why is it [Ar]4s instead of [Ar] 3d

an elastic scattering process in which a photon bounces off a molecule like a billiard ball, emerging with the same energy as it entered

rayleigh scattering

much less prevalent; for approximately one million photons rayleigh scattered by a molecule, only one photon is raman scattered

raman scattering

property whose value does not depend on the path taken to reach that specific value

what are state functions

type of thermodynamic process which occurs without transferring heat or mass between the system and its surroundings

what is an adiabatic process

PV = nRT

what is the ideal gas law

P = RT/V-b - a/V2

what is van der waals equation