What are the odds?
Give the answer to the following calculation with the correct number of significant figures.
41.84 × 100.62 × (15.227 – 15.134)
390
What is the denticity of EDTA?
hexadentate
What does LASER stand for?
light amplification by stimulated emission of radiation?
What term of the van Deemter equation is zero in GC? Explain.
The A term is zero because the column is open tubular.
Convert 4.0 km2 to square miles.
Some or all of these or all of these relations might be useful:
1 in = 2.54 cm; 1 ft = 12 in; 1 mi = 5 280 ft
1.5 mi2
A solution of sodium chloride is prepared by dissolving 2.364 (±0.002) g of NaCl in a volumetric flask containing 100.00 (±0.08) mL of water. the molar mass of sodium chloride is 58.44 amu and has negligible uncertainty. What is the concentration of sodium chloride with uncertainty?
0.4507 +/- 0.0005 M
Calculate the pH of a 0.0040 M HCN solution.
Ka = 6.2 × 10−10
5.80
What is a non-radiative transition between states with different spin called?
intersystem crossing
Calculate the resolution of two compounds separated using gas chromatography. The retention times were 628 and 642 s, and the widths at half-height were 14.1 and 16.0 s, correspondingly.
0.93
What is the molecular geometry and polarity of chlorine trifluoride?
T-shaped and polar
The following molarities were calculated from replicate standardizations of a NaOH solution: 0.5028 M, 0.5029 M, 0.5023 M. What is the 90% confidence interval for this data set?
t = 2.920
0.5027 +/- 0.0005
Calculate the thermodynamically correct pH of a solution containing 0.0050 M NaOH and 0.0090 M KCl.
The hydrated radius of OH– is 350 pm.
11.65
A solution prepared by dissolving 25.8 mg of benzene (MW = 78.11 amu) in 250.0 mL of solvent gives an absorbance of 0.266 in a 1.00-cm cell at 256 nm. Find the molar absorptivity coefficient (with units) of benzene.
201.4 M–1 cm–1
Chromatography is divided into five categories on the basis of the mechanism of interaction of the solute with the stationary phase. What are the five categories?
adsorption, partition, ion-exchange, size exclusion, and affinity
What is cell potential for the reaction:
Cu2+ (0.30 M, 𝑎𝑞)+ Mg(𝑠) → Cu(𝑠) + Mg2+ (0.20 M, 𝑎𝑞)
Helpful data:
Cu2+(aq) + 2e− → Cu(𝑠) Eo = 0.34 V
Mg2+(aq) + 2e− → Mg(𝑠) Eo = −2.37 V
2.72 V
A study of body mass index (BMI) in adults showed that for men aged 40–44, the mean BMI level is 26.7 with a standard deviation of 3.7. Assuming a normal distribution, what percentage of men in this age group have a BMI above 30?
18.67%
A 25.0-mL solutions of 0.100 M Ba2+ is titrated with 0.100 M EDTA at pH 8. Calculate the value of pBa2+ at the equivalence point.
log Kf = 7.88
α = 0.0042
3.40
A calcium ISE with a constant of 0.2123 V is placed in an unknown solution. The ISE reads a voltage of 0.1763 V. What is the activity of calcium in the unknown solution?
0.0607 M (60.7 mM)
To achieve good separation, should these terms be large or small?
separation factor, plate number, plate height
plate number large
plate height small
What is the energy (in kJ/mol) of light with a wavelength of 508 nm.
235.48 kJ/mol
The amount of copper in an unknown solution was measured using atomic absorption (AA) spectroscopy. The solution gave an absorbance of 0.215. Then a 25.00-mL aliquot of the solution was pipetted into a 50-mL beaker, and 5.000 mL of 100.0-ppm Cu2+ standard were added and mixed. The absorbance of this solution was 0.358. What was the concentration of copper in the original unknown solution?
20.0 ppm
Consider the titration of 40.0-mL of a 0.200 M diprotic acid (H2A) solution with 0.100 M NaOH. What is the pH at the second equivalence point?
pKa1 = 7.30 and pKa2 = 10.00.
11.30
A 30.0-mL aliquot of 0.00200 M KMnO4 is titrated with 0.0200 M Fe2+ in 1.00 M HNO3 using a platinum electrode. What volume of iron(II) is needed to reach the equivalence point? The relevant half-reactions are:
MnO4– + 8 H+ + 5 e– --> Mn2+ + 4 H2O Eo = 1.507 V
Fe3+ + e– --> Fe2+ Eo = 0.746 V
15 mL
A solute with a distribution constant of 6.5 is extracted from 15 mL of phase 1 into 10 mL phase 2. How many extractions are needed so that only 0.659% of solute remains in phase 1?
3
Calculate the molarity of a 70.0 wt% perchloric acid solution with a density of is 1.664 g/mL.
(MW = 100.46 amu)
11.6 M