NS5: CPF Flashcards
enthalpy: which is more thermodynamically favorable, lower or higher value?
Hess’ law
entropic penalty
heat energy of a system, delta H
The lower the enthalpic barrier, the more thermodynamically favorable the reaction is.
– Recall that Hess’ law states that ΔHrxn = Σ∆Hproducts - ΣΔHreactants
Entropic penalty: thermodynamically disfavored formation of polar solvent molecules around surface-exposed hydrophobic portions of a molecule.
Entropy increases when … (4)
The number of moles of substances in the system increase
When a solid of liquid is dissolved in a solvent
When the solubility of a gas decreases and it escapes from a solvent
When molecular complexity increases, due to the increases movement of electrons
Spontaneity
predicted by the equation ΔG = ΔH – TΔS, where ΔG is the Gibbs free energy and ΔS is change in entropy. Negative values of ΔG indicate spontaneity.
As a thermodynamic value, ∆G is also closely related to equilibrium via the equation ∆G°rxn = −RTln Keq
Specifically, an equilibrium constant (Keq) > 1 indicates that the reaction favors the production of products, which corresponds to a negative ∆G
– It then follows that when Keq < 1, ∆G > 0, and this positive ∆G indicates a nonspontaneous reaction.
Vitamins
which are water v lipid soluble
non-macronutrient compounds that are vital for healthy functioning and cannot be synthesized in adequate quantities by the body, meaning that they must be obtained from external sources
Water soluble: B and C
Lipid Soluble: A, D, E, and K
specific vitamin functions
Vitamin B is used to create coenzymes used by the body such as thru thiamine, riboflavin, biotin, pyridoxine, and some others that aid in enzymatic functions.
Vitamin C is useful in generating connective tissue, which is why vitamin C deficient people have connective tissue disorders like scurvy.
Vitamin A plays a key role in vision, growth and metabolism.
Vitamin D in calcium and phosphate absorption from the gastrointestinal tract
Vitamin E is an antioxidant and neutralizes reactive oxygen species
Vitamin K promotes coagulation and is important for bone health
explain oil-water IMFs
The Van der Waals forces that exist between molecules of water and of oil are predominately of the induced dipole-dipole type. Here, a small, temporary dipole is induced in molecules of oil by the permanent dipole of water, resulting in a weak attraction between the molecules. This is a weaker interaction than the hydrogen bonding that predominates in the interaction between water molecules.
amphiphiles + example
Amphiphiles are chemical compounds that possess both hydrophilic and hydrophobic components.
Eg. Phospholipids are triacylglyceride derivatives with two nonpolar fatty acid “tail” regions and a hydrophilic phosphate-containing “head.”
Conditions of the Doppler effect
The Doppler effect is used to analyze MOVING objects or fluids. A Doppler shift will be registered only if the fluid is moving relative to the source of the sound (the device). More specifically, at least some component of the fluid’s velocity must exist in the same directional plane as the wave’s velocity (otherwise, the device will register the fluid as not moving at all), and this component must be different from the velocity of the sound source.
Eg. If observer and source of sound are moving at the same velocity, then no shift will be observed. Additionally, if neither is moving at all, then no shift will be observed.
presbyopia vs myopia
how are they fixed
Presbyopia (far-sightedness) is the image is formed behind the retina rather than on the retina → fixed with a converging (convex) lens that will converge light rays before they can pass the retina and focus light closer to the retina.
Myopia (near-sightedness) is the image formed before the retina → fixed with a diverging (concave) lens that would spread out (diverge) the light before it reaches the retina, allowing it to pass through the cornea and be appropriately focused on the retina
Mirrors + 3 types
substances from which light rays only reflect, without any significant absorbance or refraction
Plane / linear mirror: a ray of light that hits it perpendicularly will be bounced back in the same direction; however, angled hits will reflect in the same but opposite angle to the normal
Concave mirrors: have an inward curve, causing incident light rays to CONVERGE on each other upon reflection
Convex mirrors: have an outward curve, causing incident light rays to SCATTER outwards
how do lenses differ from mirrors?
+ 2 types of lenses
Lenses differ from mirrors in that light passes thru lenses, which are typically made of glass. Thus, light is refracted both upon entering and exiting a lense.
Convex lenses cause rays to CONVERGE
Concave lenses cause them to DIVERGE
** note that it is opposite to mirrors
Thin Lens Equation
1/o + 1/i = 1/f, where o is the object distance, i is the image distance, and f is the focal length
Real images: formed by real light rays → use POSITIVE signs
– Will be on same side for mirrors, opposite side for lenses
Virtual images: formed by incidence light rays → use NEGATIVE signs
– Will be on opposite side for mirrors, same side for lenses`
Magnification
defined as –i/o, or the negative ratio of the size of the image to the size of the object
A negative magnification value means that the image is inverted compared to the object, which corresponds to it being real.
– recall that real images will be observed on the OPPOSITE SIDE in lenses
when light goes from one medium to another, it ______
changes speed
Note: Since the speed of light in a vacuum (c) is the maximum speed at which normal matter can travel in the universe, it is convenient to define the speed at which light passes through a medium with reference to the speed of light in a vacuum.
Thus, refractive index (n) of a given material is defined as n = c/(v of material)
eg. for vacuums and air, n =1
eg. for window glass, n = 1.52
Snell’s Law
n1 * sin(θ1) = n2 * sin(θ2) where θ is defined with reference to the normal, or a line that runs perpendicular to the surface on which the wave is incident
Recall that when light passes from one medium to another and changes speed, it bends; this equation lets you calculate exactly how much
define the following:
- critical angle
- total internal reflection
Critical angle = As the angle of the incident ray (θ1) increases, there will come a point where the angle of the refracted ray (θ2) reaches 90°
Total internal reflection: 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
gaseous solubility ____ as temperature ____
why?
Gaseous solubility DECREASES as the temperature INCREASES, due to an increased desire to evaporate or escape the solute.
binary fission + steps
main method through which bacteria reproduce → basically mitosis
Requires ATP, therefore aerobic bacteria divide faster than anaerobic
Three steps:
- Replication: chromosome is duplicated while the cell grows
- Segregation: chromosomes are pulled towards different sides of the cell and the cell envelope / cell wall begins to grow towards the middle of the cell
- Separation of the two daughter cells
bacterial growth timeline (4 phases)
Exponential growth process occurs when the bacteria are introduced to a new environment
Lag phase: process by which bacteria adapts to this new environment
Log phase: rampant growth that rapidly depletes available resources
Stationary phase: growth ceases as environment is unable to sustain exponential growth
Death phase: complete exhaustion of resources eventually leads to bacterial death
what can change an equilibrium constant
temperature
Nuclear magnetic resonance (NMR) spectroscopy
resonance frequencies
places sample into a magnetic field
If the sample has a nuclear spin due to an odd number of protons or neutrons, then it will be affected by the magnetic field. The atomic nuclei will align with the field (a lower-energy state) or against the field (a higher-energy state). The frequency of the transition between these states, or resonance, is measured by NMR.
RESONANCE FREQUENCIES are chemical shifts ranging from zero on the far right to positive values on the far left. — A shift of zero is arbitrarily assigned to the peak corresponding to tetramethylsilane (TMS) as a reference point
- Peaks that are shifted to the right are said to be located upfield
- peaks that are shifted to the left are said to be located downfield
H NMR
- definition
- equiv H’s
- multiple equiv H’s
spectrum can range from 0–12 ppm; location depends on the extent of shielding or deshielding experienced by 1H nuclei, which varies by functional group
Equivalent hydrogen atoms are protons that exist in the same magnetic environment; such protons do not differ in any measurable way, so they correspond to only one peak on the spectrum
If a peak corresponds to multiple equivalent hydrogen atoms, the area under that peak will be proportionally greater than the area under a peak that corresponds to a single hydrogen atom. In other words, the peak area (or integration) directly correlates to the number of protons represented by that peak.
H NMR
- splitting
each signal is affected by protons on atoms adjacent to the carbon to which the proton is attached. Splitting patterns are predicted the n + 1 rule, which states that any peak will be split into a number of smaller peaks equal to the number of adjacent hydrogen atoms plus one.
For example, if a hydrogen atom is positioned on a terminal carbon adjacent to a carbon bound to one additional hydrogen atom, the peak that represents the first hydrogen atom will be split into a doublet (1 adjacent hydrogen atom + 1 = 2).
what halogen has H-bonding
HF is the only halogen to have hydrogen bonding because it has a high level of electronegativity.
Chromatography
- definitions (2)
- interactions
- example
Stationary phase: solid phase that facilitates travel
Mobile phase: usually contains a common feature with target molecules such that interaction will slow down their travel
Molecules of interest in the mobile phase will interact with the stationary phase with different levels of intensity. Molecules that interact more strongly with the stationary phase will take longer to pass through it, whereas molecules that interact more weakly with the stationary phase will pass through it more quickly
Eg. If the stationary phase has a net positive charge, then oligopeptides with negative charges will be attracted to the stationary phase and will move more slowly through the column. In contrast, positively charged molecules will interact less with the stationary phase, thus moving faster.
Ka and Pka / Kb and Pkb
- relationship
- conjugate strength
- acid strength
- dissociation strength
The Ka and pKa values of acids are inversely related to each other (since pKa = -log [Ka], and to corresponding Kb and pKb values of their conjugate bases.
The strongest conjugate base will be produced by deprotonating the weakest acid.
As pKa values decrease, acid strength goes up.
The more acidic a compound it, the more readily it dissociates.
Strong BASES that end in “-ide” (4)
NAOH, Sodium hydroxide
LiOH, Lithium hydroxide
KOH, Potassium hydroxide
CsOH, Cesium hydroxide
Strong ACIDS that end in “-ic acid” (6)
HCl, Hydrochloric acid HBr, Hydrobromic acid HI, Hydroiodic acid H2SO4, Sulfuric acid HNO3, Nitric acid HClO4, Perchloric acid
Ka / Kb / pH / pOH relationship
look at equation for stoichiometry
Ka = [H+][A−]/[HA] and [H+] = 10-pH
pOH = -log[OH-]
In water at 25°C, Ka•Kb = 10-14. Given this, Kb = 10-14/Ka
– also pH + pOH = 14
open / closed / isolated system
Open system: matter and heat energy can be exchanged btwn surroundings and system
Closed: only heat energy, not matter, can be exchanged btwn surroundings and system
Isolated: neither matter nor heat energy can be exchanged btwn surroundings and system
ozonolysis
cleavage of an alkene or alkyne with ozone (O3) that results in the multiple carbon–carbon bond being replaced by a double bond to oxygen (carbonyl)
Sound
- composition
- speed
- frequency
made up of longitudinal, compressive waves, thus it has properties of speed, wavelength, and frequency; also produced by the displacement of air caused by the movements of and interactions between various objects in the environment.
Speed of sound is not constant → sound waves move more quickly through relatively non-compressible, or stiffer media; it also increases with temperature
Frequency is related to pitch, or how we perceive sounds as high or low, with high-frequency sounds corresponding to high pitch and low-frequency sounds corresponding to low pitch
intensity of sound
measure of the power delivered by sound over a given area → units being W/m2, or a decibel (dB)
The decibel scale is a logarithmic scale expressing the intensity of a sound as its ratio to that of the smallest detectable sound intensity I0
dB = 10log(I/I0), where I0 is 1 × 10−12 W/m2
A single sports fan is capable of yelling at an intensity level of 80 dB from a given distance. If 10,000 similar fans were all yelling from the same distance, which of the following would be closest to the observed intensity level?
10,000 fans would be capable of yelling at an intensity 10,000, or 104, times greater than the single fan alone.
According to the decibel scale, this would correspond to an increase of 40 dB, because 10log(10-4) = 40.
Thus, we would perceive an intensity level of 120 dB from the crowd of 10,000.
standing waves
take place when waves propagate through media that are physically constrained in one way or another
sinusoidal in shape and have areas where there is no displacement (aka NODES; corresponding to what would look like y = 0 on a standard sine curve graph) and areas with maximal displacement (aka ANTI-NODES, corresponding to the amplitude of the resultant standard waves).
wavelength of a standing wave in a closed-closed or open-open space is given by the following equation: λ = 2L / n where λ = wavelength, L = length and n = harmonic
waves
- mechanical (2)
- electromagnetic
formed when a pattern of periodic motion (or oscillation) propagates through space
Mechanical waves: involve the actual physical motion of particles; aka compression waves bc essentially results in a pushing-and-pulling motion → eg. sound
- Transverse: direction of the displacement of the particles is perpendicular to axis through which the wave propagates
- Longitudinal: … parallel …
- The amplitude of a mechanical wave refers to how far particles are displaced from baseline.
Electromagnetic waves: can move through vacuum → eg. light
what are the universal properties for all waves and how are they related?
v = λf
wavelength (λ): the spatial interval over which a waveform repeats itself
propagation speed (v): the speed with which a wave signal spreads through space
frequency (f): the number of wavelengths that go by per second → also 1/T
period (T): the time that separates adjacent peaks
Capacitance is directly proportional to _____ and inversely proportional to _____, therefore ____.
Capacitance is directly proportional to area but inversely proportional to the distance between the two sides of the capacitor.
Thus, decreasing the width of the membrane would decrease the distance btwn the two sides, thus actually increasing capacitance.
specific gravity
volume
Specific gravity relates the density of an object (or fluid, as is the case here) to the density of water, which is 1000 kg/m3. Note also that 1000 L = 1 m3.
Volume = mass / density
