Physics II: 4-6, 9-10 Flashcards

Question

how do catalysts affect reaction rate?

Answer 1

increase reaction rate without being consumed in the rxn lowers activation energy for both forward and backward rxn

Answer 2

increase reaction rate without being consumed in rxn stabilize reactants so as to reduce the activation energy necessary for the rxn to proceed

Answer 3

catalyst is in same phase as reactants

Answer 4

catalyst is in a different phase from reactants

Answer 5

free energies of reactants or products or difference between them don't change nonspontaneous rxns into spontaneous ones (only make spontaneous ones move quicker) do not impact equilibrium position or measurement of K_eq

Answer 6

experimentally

Answer 7

rate = k[A]^x[B]^y aA + bB -\> cC + dD

Answer 8

Δrate = Δ[A]^x multiplication factors

Answer 9

rate of formation of product C is independent of change sin concentrations of any of the reactants

Answer 10

rate = k[A]⁰[B]⁰ = k k units: M/s

Answer 11

change temperature, add catalyst

Answer 12

conc vs time: linear, k = -slope

Answer 13

have a nonconstant rate that depends on the concentration of a reactant

Answer 14

rate = k[A]¹ k units = s^-1

Answer 15

first order reaction

Answer 16

[A]_t = [A]₀e^-kt

Answer 17

conc vs time: nonlinear ln[A] vs time: k = -slope

Answer 18

nonconstant rate that depends on the concentration of a reactant

Answer 19

rate = k[A]¹[B]¹ OR k[A]² k units = 1/Ms

Answer 20

conc vs time: nonlinear 1/[A] vs time: slope = k

Answer 21

have a rate order that changes over time

Answer 22

have noninteger orders

Answer 23

first order wrt A

Answer 24

second order wrt A

Answer 25

Rate = change in concentration / change in time

Answer 26

True. The Rate-Determining Step is able to control the rate of the overall reaction by acting as a kinetic bottleneck, preventing the speed of the reaction being faster than the slowest step involved.

Answer 27

(C) The size of the reagents The 3 main factors determining a reaction rate are: I. The energy of the reagents II. The orientation of the colliding molecules III. How frequently the reagent molecules collide

Answer 28

eventually reach state in which energy is minimized and entropy is maximized

Answer 29

forward and reverse reactions are occurring at a constant rate

Answer 30

gives the expression for equilibrium constant, Keq, and the reaction quotient, Q, pure solids and liquids do not appear

Answer 31

Q calculated value that relates the reactant and product concentrations at any given time during a reaction

Answer 32

ratio of products to reactants at equilibrium constant at a constant temp

Answer 33

entropy is at a max gibbs free energy is at a min

Answer 34

more reactants than products rxn proceeds in forward direction

Answer 35

dynamic equilbrium reactants = products forward rate = reverse rate

Answer 36

more products than reactants reaction moves in reverse direction

Answer 37

the farther to the right the equilibrium position

Answer 38

negligible

Answer 39

skip the box and go straight the the Keq eq

Answer 40

if stress is applied to a system, the system shifts to relieve that applied stress

Answer 41

changes in: concentration, pressure and volume, and temp

Answer 42

to the right

Answer 43

to the left

Answer 44

volume decreases and pressure increases

Answer 45

volume increases and pressure decreases

Answer 46

toward the side with fewer moles of gas

Answer 47

toward the side with more moles of gas

Answer 48

to the right

Answer 49

to the right

Answer 50

to the left

Answer 51

to the left

Answer 52

reactant ΔH \> 0

Answer 53

product ΔH \< 0

Answer 54

higher in free energy than thermodynamic products can form at lower temps fast products

Answer 55

lower in free energy than kinetic products more stable slower

Answer 56

The Activation Energy for the forward reaction is low enough to be achievable in nature, whereas the backwards reaction must have such a high activation energy that this reaction is unlikely to occur.

Answer 57

This means that for every 1,000 collisions, 3.74 collisions will result in a successful reaction. The higher the f, the higher the success rate of reactions.

Answer 58

Increasing the Activation Energy will decrease the frequency of successful collisions. Increasing the Temperature will increase the frequency of successful collisions.

Answer 59

In a unimolecular reaction, one molecule participates in the reaction: A -\> products. In a bimolecular reaction, two molecules participate in the reaction: A + B -\> products.

Answer 60

True. You can write the rate law for one-step (elementary) reactions simply based on the reaction formula (A + B -\> C). When dealing with multi-step reactions, however, you will need to determine the rate law experimentally.

Answer 61

True. The rate law for the overall reaction is equal to the rate law of the Rate-limiting Step.

Answer 62

(B) Kinetic and Thermodynamic Activation Energy plays a key role in determining if a reaction is under Kinetic or Thermodynamic Control, and which type of product is formed.

Answer 63

∆G = ∆G° + RTlnQ ``` ∆G = Gibb's Free Energy ∆G° = Standard Gibb's Free Energy R = Gas Constant (8.314J/molK) T = Temperature (298 K at standard conditions) Q = Reaction Quotient ```

Answer 64

* First, balance the reaction as follows: * 2O2 + N2H2 -\> 2NO2 + H2 * Then write the Keq expression as follows: * Keq = [NO2]^2[H2] / ([O2]^2[N2H2])

Answer 65

∆G° = -RTlnK ``` ∆G° = Standard Gibb's Free Energy R = Gas Constant (8.314J/molK) T = Temperature (298 K at standard conditions) K = Equilibrium Constant ```

Answer 66

∆G° = 0 when K = 1. ∆G° \> 0 when K \< 1. ∆G° \< 0 when K \> 1.

Answer 67

1. generate a hypothesis 1. testable question 2. gather data and resources 3. form hypothesis 2. test hypothesis 1. collect new data 2. analyze data 3. interpret data and existing hypothesis 3. publish and verify results

Answer 68

proposed explanation or answer to testable question often in form of if then statement

Answer 69

assesses the value of a research question on the basis of whether or not it is **feasible, interesting, novel, ethical, relevant**

Answer 70

uses chemicals, cell cultures, or animal subjects experiment based - good for demonstrating causality

Answer 71

manipulated variable

Answer 72

measured or observed

Answer 73

used to correct for any influences of an intervention that are not part of the model

Answer 74

ensure that a change in the dependent variable occurs when expected

Answer 75

ensure that no change in the dependent variable occurs when none is expected

Answer 76

aka validity ability to measure a **true value**

Answer 77

aka reliability ability to read consistently, or within a narrow range

Answer 78

method used to control for differences between subject groups

Answer 79

only the patient or the assessor is blinded

Answer 80

investigator, subject, and assessor all do not know th subject's group

Answer 81

an error in data analysis that results from a common connection of both the dependent and independent variables to a third variable

Answer 82

cohort studies, cross sectional studies, case control studies

Answer 83

record exposures throughout time and then assess the rate of a certain outcome

Answer 84

assess both exposure and outcome at the same point in time

Answer 85

assess outcome status and then look backward to assess exposure history

Answer 86

describe the components of an observed relationship that increase the likelihood of causality in the relationship 1. temporality - **necessary** 2. strength 3. dose response relationship 4. consistency 5. plausibility 6. consideration of alternative explanations 7. experiment 8. specificity 9. coherence

Answer 87

systematic and results from a problem during data collection

Answer 88

sample not representative of the population

Answer 89

educated professionals use their knowledge in an inconsistent way by searching for an outcome disproportionately in certain populations

Answer 90

aka observation bias changes in behavior, by the subject or experimenter or both, that occur as a result of the knowledge that the subject is being observed

Answer 91

bias - systematic (unidirectional) error that occurs during data collection confounding - error that occurs during data analysis

Answer 92

beneficence nonmalificence respect for patient autonomy justice

Answer 93

autonomy, informed consent, confidentiality

Answer 94

dictates which study questions are worth pursing and which subjects to use

Answer 95

requires use to do the most good wit the least harm equipoise

Answer 96

autonomy: right of an indvidual to make decisions on their own behalf and to have those decisions be respected respect for persons: honestly, confidentiality, informed consent, freedom from coercion

Answer 97

compensatory influence: does not impact the decision to participate coercive influence: subject loses autonomy to make the decision to participate

Answer 98

all of the individuals who share a set of charcteristics

Answer 99

information that is calculated using every person in a population

Answer 100

subset of population

Answer 101

sample data

Answer 102

identification of causality in a study between the independent and dependent variables

Answer 103

genralizbility

Answer 104

low likelihood of the experimental findings being due to chance

Answer 105

usefulness or importance of experimental findings to patient care or patient outcomes

Answer 106

subject to more random variation than larger samples in larger sample, outliers will have less of an effect on results

Answer 107

statistical significance and clinical significance

Answer 108

measures absorption of infrared light, which causes molecular vibration (stretching, bending, twisting, and folding)

Answer 109

used in IR spectroscopy wavenumber = 1/λ

Answer 110

percent transmittance vs wavenumber

Answer 111

4000 - 400 cm^-1

Answer 112

1500 - 400 cm^-1 contains a number of peaks that can be used by experts to identify a compound

Answer 113

they involve no change in dipole movement

Answer 114

3000-3300 cm^-1 broad/round

Answer 115

1750 cm^-1 sharp

Answer 116

3300 cm^-1 sharp

Answer 117

IR spectra range O-H

Answer 118

IR spectra range C=O

Answer 119

IR spectra range N-H

Answer 120

amount of light that passes through the sample and reaches the detector

Answer 121

alcohol: 3300 cm^-1 carboxylic acid: 3000 cm^-1

Answer 122

measures absorption of IR light by specific bonds that vibrate these vibrations cause changes in the dipole moment of the molecule that can be measured

Answer 123

measures absorption of UV light, which causes the movement of electrons between molecular orbitals

Answer 124

passing UV light through a sample that is usually dissolved in an inert, nonabsorbing solvent and recording the absorbance

Answer 125

the lower the energy of the transition the greater the wavelength of maximum absorbance

Answer 126

studying compounds containing double bodns or heteroatoms with lone pairs that create **conjugated** systems

Answer 127

percent transmittance or absorbance vs wavelength

Answer 128

small enough energy difference between its HOMO and LUMO to permit an electron to move from one orbital to the other

Answer 129

occurs in molecules with unhybridized p-orbitals can be excited by UV light

Answer 130

shifts it -\> higher max wavelengths (lower frequencies)

Answer 131

measures alignment of nuclear spin with an applied magnetic field, which depends on the magnetic environment of the nucleus itself

Answer 132

determining the structure (connectivity) of a compound, including functional groups

Answer 133

* based on fact that certain atomic nuclei have magnetic moments that are oriented at random * when nuclei are placed in a magnetic field, their magnetic moments tend to align either with or against the direction of the applied field * radiofrequency pulses push the nucleus from the alpha state to the beta state * these frequencies can be measured

Answer 134

lower energy nuclei with magnetic moments

Answer 135

higher energy nuclei with magnetic moments

Answer 136

medical application of NMR reveals the relative density of specific types of protons

Answer 137

frequency vs absorption of energy starndardized by using chemical shift use TMS to calibrate

Answer 138

has chemical shift of 0 ppm

Answer 139

nuclei with odd mass numbers, odd atomic numbers, or both

Answer 140

each unique group of protons has its own peak

Answer 141

proton NMR area under the curve proportional to the number of protons contained under the peak

Answer 142

occurs when electron withdrawing groups pull electron density away from the nucleus, allowing it to be more easily affected y the magnetic field moves a peak further downfield

Answer 143

downfield left

Answer 144

upfield right

Answer 145

occurs when electron donating groups shield nuclei moves a peak further upfield

Answer 146

shielding or deshielding effects reflects the chemical environment of the protons

Answer 147

represents the number of adjacent hydorgens split into n + 1 subpeaks, where n is the number of adjacent hydrogens

Answer 148

when hydrogen are on adjacent atoms, they interfere with each other's magnetic environment include doublets, triplets, and multiplets

Answer 149

if a proton has n protons that are 3 bonds away, it will be split into n+1 pekas (do not include protons attached to oxygen or nitrogen)

Answer 150

* determining the relative number of protons and their relative chemical environments * showing how many adjacent protons there are by splitting patterns * inferring certain functional groups

Answer 151

counting the number of peaks and unique hydrogens may be enough (do not count the peak for TMS)

Answer 152

10.5-12 ppm

Answer 153

NMR range protons on sp3 hybridized carbons

Answer 154

NMR range protons on sp2 hybridized carbons

Answer 155

NMR range protons on sp hybridized carbosn

Answer 156

NMR range aldehyde hydrogens

Answer 157

NMR range carboxylic acid hydrogens

Answer 158

NMR range aromatic hydrogens

Answer 159

False. The more densely the molecules are packed in the medium that light travels through, the slower the speed. This is why the speed of light in a vacuum is 3 x 10^8 m/s, whereas in Water, it is only 2.25 x 10^8 m/s!

Answer 160

At that wavelength of light, 100 percent of the wave is not being transmitted through the compound because it is being absorbed by a bond causing it to stretch.

Answer 161

(A) Transmittance + Absorbance = 100% This also means that 100%- (Transmittance) = Absorbance!

Answer 162

The Diagnostic Region of an IR Spectra occurs above a wavenumber of 1500. It is useful for identifying which functional groups are present in a compound. The Fingerprint Region of an IR Spectra occurs below a wavenumber of 1500. It is not especially useful for determining functional groups, but every compound has a unique fingerprint region, which can allow you to exactly identify a compound given the proper tools.

Answer 163

(A) I \< II \< III In order of lowest wavenumber to highest wavenumber: Csp3-H \< Csp2-H \< Csp-H. This is due to increasing s character in the bonds.

Answer 164

(C) 5 I would notice that the lowest value is 11.3, which when divided by the total gives you a value close to .1; thus, I would know that this peak corresponds to 1/10th of the total hydrogens (10). Representing a single hydrogen. Because 57.6 is about 5 times larger, it must represent 5 hydrogens.

Answer 165

(B) 2:3:3 Looking at this, I can round these numbers off to 27, 40.5 and 40.5, and I see that if you divide by a factor of 13.5, you can see a 2:3:3 ratio. You could also try dividing 40.1 by 27.1, and get about 3/2.

Answer 166

Splitting is the splitting of a peak that occurs when you have nonequivalent protons next to each other. It is caused by the idea that the environment of a proton will be different when the neighboring proton is in its β versus α state.

Answer 167

I. Triplet (B) 2 II. Doublet (A) I III. Quintet (D) 4

Answer 168

True. If you see a singlet, there cannot be any splitting of that Hydrogen.

Answer 169

(B) II only To appear on an NMR, an atom must have an odd mass number, an odd atomic number, or both. Only O-15 meets either of these criteria.

Answer 170

Carbon-13, since it has an odd mass number.

Answer 171

(C) Stiffer, higher wavenumber, more Because a double bond is Stiffer than a single bond, it requires a higher wavenumber to vibrate the bond, which means there is More energy needed to cause that vibration.

Answer 172

False. If the Hydrogen in the Carboxylic Acid were replaced by Tritium (Hydrogen with an atomic mass of 3), then the O-T bond would have a lower wavenumber than the original O-H bond. This is because a more massive atom will vibrate more slowly and at lower frequencies.

Answer 173

The easiest way to remember this is by comparing C-H and C-C bonds. C-H bonds have a wavenumber near 3000 cm^-1, whereas C-C bonds are in the fingerprint region below1500 cm^-1.

Answer 174

(D) Negative Correlation Since an increase in one factor leads to a decrease in the other, this is a negative correlation.

Answer 175

(B) Positive Correlation Since an increase in one will lead to an increase in the other, this is a positive correlation.

Answer 176

False. A more conjugated compound will be more stable than less conjugated systems if one electron pair is excited above ground state, so it can use less energy (longer wavelengths) to be excited.

Answer 177

You'd expect the compound to be red since it's complimentary color, green, is what is being absorbed.

Answer 178

The greater the conjugation, the higher the wavelength. The higher the wavelength, the less likely for the wavelength to be UV light and more likely to be in the visible light spectrum.

Answer 179

(D) Towards you This can be determined using the right-hand rule.

Answer 180

(A) Proton A because going from the α to the β state will take more energy than with Proton B. Proton A is more deshielded, resulting in a greater βeff, which results in a greater energy difference between the α and the β state, which results in a greater energy required. Greater energy corresponds to a higher frequency, which is farther downfield in an NMR Spectra.

Answer 181

To say that protons are "chemically equivalent" is to say that the protons are in the same magnetic environment. These protons will therefore correspond to the same, single peak in an IR Spectra.

Answer 182

(B) 2 Propane has 8 protons total, with 2 being in one magnetic environment and 6 being in another. Because there are two magnetic environments, propane will display two peaks in an NMR Spectra.

Answer 183

(D) 4 1-Propanol has 8 total protons in four different environments: 2 on carbon 1, 2 on carbon 2, 3 on carbon 3, and the final one bound to the oxygen. Because there are 4 magnetic environments, propanol will display 4 peaks on an NMR spectra.

Answer 184

Alkenes are sp2-hybridized, giving them more s character than the sp3-hybridized orbitals of alkanes. sp2 orbitals have greater s-character and correspond with being closer to the nucleus and having greater electron density, which would result in greater deshielding of a nearby proton.

Physics II: 4-6, 9-10 Flashcards

(219 cards)