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Science · Drill 40

Science practice 40

8 questions ~9 min recommended
⏱ 00:00
Score
—

0.08
0.06
0.04
0.02 -
0.00
400
TTTT
500
600
700
Wavelength (nm)
800

Sample
1
2
3
4
5
Concentration of NiSO 4(ag) (mol/L)
0.08
0.16
0.24
0.32
0.40
Absorbance
0.091
0.182
0.273
0.363
0.451

Two investigations were conducted on a sample of green nickel sulfate (NiSO4) that was dissolved in water. The first investigation placed a sample of the nickel sulfate into a spectrometer. Most solutions absorb some wavelengths of light and allow other wavelengths to pass right through. The spectrometer changed the wavelength of light shining into the solution and recorded how much of the light was absorbed by the solution. An absorbance of 0.00 would indicate that all of the light shone into the solution passed through with no light being absorbed. Figure 11.4 shows the result of absorbance versus wavelength for a sample of NiSO4(aq).

Figure 11.4

The next experiment used five different solutions of NiSO4(aq) at different known concentrations (measured in molarity). Each solution was placed in a spectrometer set at 740 nm, and light was shone into each sample to determine the absorbance of each of the five solutions. Table 11.3 shows the results.

TABLE 11.3

1. Which wavelength of light was absorbed to the greatest degree in the first investigation?

2. The wavelength of 490 nm is green light. Why is the absorbance of NiSO4 low at 490 nm?

3. What conclusions can be drawn from the data collected in Table 11.3?

4. Which of the following statements accurately describes the trend found in Table 11.3?

5. Which set of data would best represent the results if Investigation 2 were repeated with a wavelength of 490 nm instead of 740 nm?

Concentration

6. The process of spectrometry works well on colored solutions such as green nickel sulfate (NiSO4) and cupric sulfate (CuSO4). Why might spectrometry not work well on solutions such as table salt dissolved in water (NaCl(aq))?

7. Experiment 2 was repeated with a sixth sample of NiSO4 solution with a concentration of 0.48 mol/L. However, the test tube had fingerprints on the glass where the light passed through. The fingerprints absorbed some light from the spectrometer. What would be an expected value for the absorbance?

8. What would be the results of Investigation 1 if a more concentrated solution of NiSO4(aq) were used to make the graph in the table?

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