Organic/General/Physics
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- What is the relationship between alpha and beta anomers of carbohydrates?
- they are diasteromers; specific rotation cannot be determined from one another
- What is an epimer?
- aldose steroisomers that differ only about the configuration of one carbon
- What is an anomer?
- cyclic steroisomer that differs about the new chiral carbon that was formed during cyclic development
- What occurs to hemiacetal rings when they are exposed to water?
- they spontaneously open and then reform to the alpha or beta anomer; this is called mutarotation
- Which anomer configuration is more favored?
- the beta anomer is more favored because the hydroxyl is equatorial to the ring, instead of axial as it is in the alpha anomer
- What will happen to a monosaccharide in the presence of acidic anhydride and base?
- all of the alcohol side chains will be turned into ester groups
- What does PCC do?
- oxidizes alcohols to the keton
- T/F: diastereomers can rotate plane polarized light
- true
- In the Woff Kishner reduction, reaction with NH2NH2 will form the intermediate ____ while addition of base will form the _____.
- hydrazone (HC=NNH2); methyl (R group)
- Which of the amines is most soluble in water?
- the quaternary amine
- The reaction of a nitrile with LiAlH4 will form:
- an amine
- T/F: the higher the MW, the higher the boiling point
- true; the higher the MW, the harder it is to "push" that molecule into the gas phase
- T/F: an anomer formed from an aldose will differ in the configuration about the first carbon.
- true
- Anomers that differ in the configuration about their second carbon are called:
- epimers
- Where are aminopeptidase and carboxypeptidase secreted from, respectively?
- intestinal glands; pancreas
- Galvanic cells have a ____ E value while electrolytic cells have a ______ E value.
- positive; negative
- The electrode in which electrons are flowing into undergoes (oxidation/reduction)?
- reduction
- A galvanic cell connects and powers a light bulb; the light bulb will continue to glow until:
- the cell has reached equilibrium
- What is a faraday?
- the magnitude of charge of one mole of electrons.
- Bromine with CCl4 is a common test for the presence of:
- double bonds
- The electric field points in the direction of a _____ charge.
- positive
- When light travels from a greater "n" to a lower "n," the refracted ray is bent away from the normal.
- true
- T/F: When light travels from a smaller "n" to a larger "n", the refracted ray is bent towards the normal.
- true
- How are beats produced?
- from two overlapping waves with slightly different frequencies.
- T/F: standing waves can be either transverse or longitudinal.
- true
- T/F: a node is a place where max vibration occurs.
- false; a node is a place that exhibits no vibration, while an antinode is a place where max vibration occurs
- T/F: an antinode is just part of the wave with max amplitude
- true
- The smallest frequency corresponding to a one loop pattern is f1. What is the frequency needed to establish a 3 loop pattern?
- 3f1
- What is the harmonic number?
- the number corresponds to the number of loops in the standing wave pattern.
- What is the fundemental frequency?
- it is the first frequency of a harmonic; the rest of the frequencies are called overtones
- What is a standing wave?
- a wave that does not travel in one direction or the other
- How do standing waves arise?
- because identical waves travel on the string in opposite directions and combine
- A standing wave is established when the string is vibrated with a frequency of:
- 2*Length of string/wave speed
- What is the natural frequency?
- the frequency at which resonance occurs
- What is the equation for the series of natural frequencies that lead to standing waves on a string fixed at both ends?
- natural frequency = n(v/2L)
- What is the natural frequency for a tube open at both ends?
- n(v/2L)
- What is the natural frequency for a tube open at only one end?
- n(v/4L)
- Does temperature change pitch?
- yes
- Does pressure change pitch?
- no
- According to the kinetic molecular theory of gases, pressure increases as volume decreases because:
- the collision of gas particles with the cylinder increase in frequency.
- How does one convert from molarity to normality and visa versa?
-
N = nM
M = N/n - A rocket takes off and dissociates as it ascends into space. What occurs to the initial and final momentum of the pieces?
- momentum is conserved; vectors should cancel
- The larger the binding energy, the _____ the nucleus.
- more stable; tightly bound
- The stronger the electrostatic force in teh nucleus, the _____ the binding energy.
- weaker
- What form of energy transfer can occur in a vacuum?
- radiation
- An object weight 180N on the earth's surface. How much does it weigh when it's distance from the earth's surface is tripled?
- 180/9 = 20N; Gm(e)m/r(squared) = mg; m is constant so g must be changing
- In a magnetic field, if the direction of a particle points with the vector qv, then the charge must be ______.
- positive
- As a liquid begins to boil, what occurs to the vapor pressure?
- increases; to keep pressure constant, volume must be increased to lower pressure increase
- What are the four postulates of the kinetic molecular theory of gases?
-
1. gas particles are separated by distances must greater than their size
2. only totally elastic IF's occur
3. KE is directly proportional to temperature
4. gas particles are moving in a random fashion with various distribution of speeds - What does the Van der Waals equation account for?
- the IF's and volumes of real gases
- T/F: ideal gases never condense
- true
- At high pressures, real gases occupy volumes ____ than ideal gases.
- larger
- T/F: ideal gases interact
- false
- The higher the temperature, the more _____ a gas.
- energetic; KE increases with T
- Force * velocity is equal to:
- power
- When pH = pKa, then [HA] = ?
- [A-]
- T/F: for resistors and capacitors in parallel, the voltage across the resistor will equal the voltage across the capacitor
- true
- tertiary alkyl halides will form ______ in presence of strong base.
- alkenes via E2
- Will a tertiary or primary alcohol under condensation at a faster rate?
- tertiary; more stable carbocation; condensation requires carbocation
- What must be true fo a ketone if during enolate formation, it undergoes racemization?
- the alpha carbon must be chiral
- How can pressure be altered in a closed container in order to increase the rate at which ice will melt?
- raising the pressure shifts the equilibrium towards the phase that is most dense (in this case, water is more dense than ice)
- What does it mean for two species to be isoelectronic?
- they have the same electron configuration
- For a given exothermic reaction, how are enthalpy, Ea (forward) and Ea (reverse) related?
- (change in enthalpy) + Ea (forward) = Ea (reverse)
- T/F: volume, entropy, enthalpy, and work are all state functions.
- false; work is not a state function because it is dependent on the path taken
- What conditions does a real gas differ in behavior from an ideal gas?
- low T and high P
- What are the chalcogens?
- the group directly left of the halogens
- A buffer consists of a:
- weak acid with it's conjugate base
- In Hooke's law, "k" stands for:
- the stiffness of the spring; as k increase, it becomes more difficult to compress or stretch the spring
- Total mechanical energy is conserved if:
- nonconservative forces do no work