Chem/Phys Flashcards
What expression gives the amount of light energy (in J per photon) that is converted to other forms between the fluorescence excitation and emission events?
A.(6.62 × 10–34) × (3.0 × 108)
B.(6.62 × 10–34) × (3.0 × 108) × (360 × 10–9)
C.(6.62 × 10–34) × (3.0 × 108) × [1 / (360 × 10–9) – 1 / (440 × 10–9)]
D.(6.62 × 10–34) × (3.0 × 108) / (440 × 10–9)
The answer to this question is C because the equation of interest is E = hf = hc/λ, where h = 6.62 × 10 −34 J ∙ s and c = 3 × 10 8 m/s. Excitation occurs at λe = 360 nm, but fluorescence is observed at λf = 440 nm. This implies that an energy of E = (6.62 × 10 −34) × (3 × 10 8) × [1 / (360 × 10 −9) − 1 / (440 × 10 −9)] J per photon is converted to other forms between the excitation and fluorescence events.
What is the total number of sp2-hybridized carbon atoms present in the fluorophore used in the experiments?
A.4
B.6
C.9
D.10
The answer to this question is C. The fluorophore used in the experiments was AMC. There are 10 carbon atoms in AMC. Nine of these carbon atoms are AX3 systems that possess exactly one doubly bonded atom and are therefore sp2-hybridized.
What is the total number of sp2-hybridized carbon atoms present in the fluorophore used in the experiments?
A.4
B.6
C.9
D.10
The answer to this question is C. The fluorophore used in the experiments was AMC. There are 10 carbon atoms in AMC. Nine of these carbon atoms are AX3 systems that possess exactly one doubly bonded atom and are therefore sp2-hybridized.
Four organic compounds: 2-butanone, n-pentane, propanoic acid, and n-butanol, present as a mixture, are separated by column chromatography using silica gel with benzene as the eluent. What is the expected order of elution of these four organic compounds from first to last?
A.n-Pentane → 2-butanone → n-butanol → propanoic acid
B.n-Pentane → n-butanol → 2-butanone → propanoic acid
C.Propanoic acid → n-butanol → 2-butanone → n-pentane
D.Propanoic acid → 2-butanone → n-butanol → n-pentane
The answer to this question is A. The four compounds have comparable molecular weights, so the order of elution will depend on the polarity of the molecule. Since silica gel serves as the stationary phase for the experiment, increasing the polarity of the eluting molecule will increase its affinity for the stationary phase and increase the elution time (decreased Rf).
NADH –> NAD+ is a(n) _____ reaction.
oxidation
NAD+ –> NADH is a(n) _____ reaction.
reduction
What is the Venturi effect?
The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe
Henderson-Hasselbach equation
pH = pKa + log([base]/[acid])
pKa is −log10 Ka
An inflatable cuff was used to temporarily stop blood flow in an upper arm artery. While releasing the pressure to deflate the cuff, a stethoscope was used to listen to blood flow in the forearm. The blood pressure reading was 130/85. Given this information, which of the following statements is LEAST likely to be true?
A.85 mmHg was the diastolic pressure.
B.Blood flow was heard when the pressure of the cuff was greater than 130 mmHg.
C.130 mmHg was the systolic pressure.
D.Blood flow was heard when the pressure of the cuff was 90 mmHg.
The answer to this question is B because the question indicates that the cuff was inflated to temporarily stop blood flow in the artery. The systolic pressure is determined from the first sound of blood flow that can be heard once the pressure exerted by the inflatable cuff falls below the pressure in the artery. The blood pressure reading was 130/85, which indicates that blood flow started again when the pressure was 130 mmHg. Therefore, blood flow was not heard when the pressure of the cuff was greater than 130 mmHg. A is not the correct response because the lower number of the blood pressure reading represents the diastolic pressure. C is not the correct response because the higher number of the blood pressure reading represents the systolic pressure. D is not the correct response because blood flow would be heard when the pressure of the cuff is 90 mmHg, as this pressure is higher than the diastolic pressure.
