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14 questions
Select all choices that represent ppm.
The concentration of chromium in blood serum of a control and a diseased group were measured. Which of the following equation would you use to evaluate if the results of the two groups were statistically different or same?
None of the choices.
Analysis for a sample was done in triplicate. To compare if the determined concentration is statistically the same or different at the 95% confidence interval, what value of tcrit should be used?
Which of the following equations should you use to determine the standard deviation of the calculated result for this calculation: y = 2.77 (±0.06) × 0.36(±0.004)
None of the choices.
A statistical test was applied to test if a method #1 is statistically the same or different compared to method #2. For the following set of data from each method at the 95% confidence interval, what value of tcrit should be used in the statistical test?
Between NaCN (sodium cyanide) and NaF (sodium fluoride), which salt would yield a more basic solution when dissolved in deionized water?
Ka of HCN = 6.2 × 10-10
Ka of HF = 6.8 × 10-4
NaCN
NaF
What is the pH of an aqueous solution of 0.150 M of NH4CN (ammonium cyanide)?
Ka of NH4+: 5.7 × 10-10
Ka of HCN: 6.2 × 10-10
pH < 7
pH ≈ 7
pH > 7
pH = 14
pH cannot be determined.
Which of the following titration curves best represents the titration of 0.1M NaCH3COO (sodium acetate) with 0.1 M HCl?
For the titration of 40 mL 0.10 M weak monoprotic acid, HA, with 0.10 M of NaOH (sodium hydroxide), what volume of NaOH should be added to the acid solution to reach the equivalence point? Ka of HA = 1 × 10-8
50 mL
20 mL
30 mL
40 mL
For the titration of 40 mL 0.10 M NaHCOO (sodium formate), with 0.10 M HCl (hydrochloric acid) what is the pH of the solution in the flask at the equivalence point?
Ka of HCOOH = 1.8 × 10-4
pH < 7
pH = 7
pH > 7
pH = 14
pH cannot be determined.
The following is a titration curve (solid line) of 40 mL 0.10 M unknown weak monoprotic acid, with 0.10 M NaOH (sodium hydroxide). The dotted line indicates the volume of NaOH added to reach the equivalence point. What is the value of pKa for the unknown acid?
9
12
3
5
Cannot be determined.
The following is a titration curve (solid line) of 40 mL 0.10 M unknown weak monoprotic acid, with 0.10 M NaOH. The dotted line indicates the volume of HCl added to reach the equivalence point. Which of the following pH indicator is the most suitable choice for this titration?
thymol blue
(pKa: 1.7)
methyl orange (pKa: 3.4)
None of the choices are suitable.
bromophenol blue (pKa: 3.85)
All of the choices are suitable.
Which of the following conjugate acid-base pair is most suitable for the preparation of a buffer solution that has a final pH value of 4?
HSO4- and SO42- (pka of HSO4- = 1.99)
HCOOH and HCOO- (pka of HCOOH = 3.74)
HOCl and -OCl (pka of HOCl = 7.02)
HCN and CN- (pka of HCN = 9.20)
Which of the following mixture have the greatest buffer capacity?
0.20 M NaOH
and
0.60 M HCl
0.05 M CH3COOH and
0.10 M NaCH3COO
0.10 M CH3COOH and
0.10 M NaCH3COO
0.52 M CH3COOH and
0.52 M NaCH3COO
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