You have measured the response for a set of 4 method blanks for your method used to measure caffeine in beverages. The blanks give the following response units (0.1121,0.1176,0.1132,0.1211), with a mean signal of 0.116 and a standard deviation of 0.00415 . If the calibration curve equation, where the units of x are ppm caffeine, is y=0.3761x+0.1150, and we assume that Y_(blank ) is equal to the y-intercept of the calibration line, the lowest detectable concentration for this method is:
a) 0.0110ppm
b) 0.308ppm
c) 0.0330m(g)/(L)
d) -0.273m(g)/(L)
e) None of These
How much energy is contained in 0.0710 moles of 391nm light? N_(A)=6.022 imes 10^(23),c=2.998 imes 10^(8) (m)/(sec,h)=6.626 imes 10^(-34)J * sec.
a) 3.61 imes 10^(-20)J
b) 2.17 imes 10^(-5)J
c) 3.61 imes 10^(-29)J
d) 2.17 imes 10^(4)J
e) None of These
The best results for concentrations calculated using Beer's Law are obtained if the absorbance values are between 0.10 and 1 . What does this range correspond to in % transmittance?
a) 10%-79%
b) 1.26%-10%
c) 0.10-1%
d) 10%-100%
e) None of These
A sample containing an absorbing analyte at a concentration of 0.0090M is analyzed by UV-Vis spectroscopy and a transmittance of 84.4% is observed. A second solution, with an analyte concentration of 0.036M, in the same cuvette and instrument, is analyzed. What would you expect the observed %T to be for the 0.036M solution?
a) 21.1%
b) 0.211
c) 50.7%
d) 118%
e) None of These
CHEM31 Lecture HW Set 7
S2024
Due Monday, 4/2/2024, 11AM
5. In a calibration curve constructed for a chemical species that follows Beer's Law, the slope of the calibration line represents:
a) B
b) epsi ^(**)b
c) epsi
d) A
e) None of These
1. You have measured the response for a set of 4 method blanks for your method used to measure
caffeine in beverages.The blanks give the following response units (0.1121,0.1176,0.1132,0.1211, with a mean signal of 0.116 and a standard deviation of 0.00415. If the calibration curve equation, where the units of x are ppm caffeine, is y = 0.3761x + 0.1150, and we assume that Yblank is equal to the y-intercept of the calibration line, the lowest detectable concentration for this method is: a) 0.0110 ppm b) 0.308 ppm c) 0.0330 mg/L (p -0.273 mg/L e) None of These
2.How much energy is contained in 0.0710 moles of 391 nm light? N = 6.022 x 103, c= 2.998 x 10 m/sec, h = 6.626 10.34 J*sec. a3.61x10 b) 2.1710j c) 3.6110 (p 2.17104J e) None of These
3. The best results for concentrations calculated using Beer's Law are obtained if the absorbance values are between 0.10 and 1. What does this range correspond to in % transmittance? a) 10%-79% b) 1.26%-10% c) 0.10-1% (p 10%-100% e) None of These
A sample containing an absorbing analyte at a concentration of 0.0090 M is analyzed by UV-Vis spectroscopy and a transmittance of 84.4% is observed. A second solution, with an analyte concentration of 0.036 M, in the same cuvette and instrument, is analyzed. What would you expect the observed %T to be for the 0.036 M solution a) 21.1% b) 0.211 c) 50.7% (p 118% e) None of These
CHEM31 Lecture HW Set 7 S2024 Due Monday, 4/2/2024, 11AM
5. In a calibration curve constructed for a chemical species that follows Beer's Law, the slope of the calibration line represents: 8(e b) E*b c) & d) A e) None of These
