Question Data Table 1. Varying Concentrations of 1.0 M HCl. Concentrations # of
ID: 878117 • Letter: Q
Question
Question
Data Table 1. Varying Concentrations of 1.0 M HCl.
Concentrations
# of drops
# of drops
# of drops
Stock Solution
Stock Solution
Reaction (after mixing in well)
Reaction (after mixing in well)
Reaction Time
(seconds)
Reaction
Rate
(sec-1)
Well #
HCl
H2O
Na2S2O3
HCl
Na2S2O3
HCl
Na2S2O3
Trial 1
Trial 2
Average
C1, D1
12
0
8
1M
0.3M
0.6M
0.12M
27.44
27.40
27.42
0.0365
C2, D2
6
6
8
1M
0.3M
0.3M
0.12M
31.66
31.68
31.67
0.0316
C3, D3
4
8
8
1M
0.3M
0.2M
0.12M
46.90
46.98
46.94
0.0213
Data Table 2. Varying Concentrations of 0.3 M Na2S2O3.
Concentrations
# of drops
# of drops
# of drops
Stock Solution
Stock Solution
Reaction (after mixing in well)
Reaction (after mixing in well)
Reaction Time
(seconds)
Reaction
Rate
(sec-1)
Well #
HCl
H2O
Na2S2O3
HCl
Na2S2O3
HCl
Na2S2O3
Trial 1
Trial 2
Average
C4, D4
8
0
12
1M
0.3M
0.4M
0.18M
19.96
19.64
19.8
0.0505
C5, D5
8
6
6
1M
0.3M
0.4M
0.09M
48.69
48.63
48.66
0.2055
C6, D6
8
8
4
1M
0.3M
0.4M
0.06M
134.62
134.65
134.64
0.0074
1. Determine the Reaction Order for Na2S2O3 using calculations described in the Background section. Show your work. Note that your answer will probably not be an even whole number as it is in the examples.
2. Write the rate law for the reaction between HCl and Na2S2O3
Table 1. Known Concentration of M Drugs.
The remainder of these questions are based upon the following scenario:
A testing laboratory has been hired by a company called “Drug Company Q” to analyze a series of over-the-counter drugs that the company produces. In these over-the-counter drugs, the active ingredient is called “Active Ingredient M.” The laboratory technician collected the following data from samples with known concentrations of the Active Ingredient M. That data is shown below in Table 1.
Sample Identification Code
Sample Concentration (M)
Absorbance
Q5000
4.00 x 10-4
17.9
Q5001
3.20 x 10-4
25
Q5002
2.40 x 10-4
35.7
Q5003
1.60 x 10-4
50.2
Q5004
8.00 x 10-5
70.8
The technician also collected absorbance readings for the 5 over-the-counter drugs for review. The data collected for the 5 over-the-counter drugs is shown in Table 2.
Table 2. Absorbance Data for Over-the-Counter Drugs.
Sample Identification Code
Absorbance
M21050-1
43.7
M21050-2
44.1
M21050-3
45.8
M21050-4
42.1
M21050-5
30.1
3. Create a Beer’s law plot and best fit line for the data in Table 1.
4.Use the Beer’s law plot and best fit line to determine the concentrations for samples: M21050-1, M21050-2, M21050-3, M21050-4, M21050-5. THE CONCENTRATION OF M IN THE GIVEN SAMPLES IS 3x10-4 mol/lit
5.The company reported that sample M21050-2 has an M concentration of 0.0003M. Assuming that the results in Question C are 100% accurate and without error, is the company’s statement accurate? What is the percent error between the reported concentration and the concentration calculated in Question C?
6.By law, Drug Company Q must have an M concentration between 2.85 x 10-4 M and 3.15 x 10-4M. Do all samples analyzed meet the legal requirements? Use the information from Question C to explain your answer.
Concentrations
# of drops
# of drops
# of drops
Stock Solution
Stock Solution
Reaction (after mixing in well)
Reaction (after mixing in well)
Reaction Time
(seconds)
Reaction
Rate
(sec-1)
Well #
HCl
H2O
Na2S2O3
HCl
Na2S2O3
HCl
Na2S2O3
Trial 1
Trial 2
Average
C1, D1
12
0
8
1M
0.3M
0.6M
0.12M
27.44
27.40
27.42
0.0365
C2, D2
6
6
8
1M
0.3M
0.3M
0.12M
31.66
31.68
31.67
0.0316
C3, D3
4
8
8
1M
0.3M
0.2M
0.12M
46.90
46.98
46.94
0.0213
Explanation / Answer
1. The order of reaction with respect to Na2S2O3 is first order.
change in concentration of Na2S2O3 to half reduces the rate to half.
2. Rate law, rate = k[Na2S2O3]^1[HCl]^0
3. The plot of absorbance vs. conc. gives a straight line
4. The concentrations calculated are,
Sample Calculated concentration (M)
M21050-1 9.76 x 10^-4
M21050-2 9.85 x 10^-4
M21050-3 1.02 x 10^-3
M21050-4 9.41 x 10^-4
M21050-5 6.73 x 10^-4
5. No the analysis by the drug company does not match with the calclated concentration of M21050-2. The value calculated in the problem by the given set of data is shown in 4. We have an approximately 30% error in this case.
6. No, all the samples do not meet the concentration criteria. Some of the data fall out of this required range as can be clearly seen from the data set given above.
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