Quiz 2 (Instrumental Analysis)

Extraction can be conducted on organic analytes prior UV-Visible spectroscopy method. Why the absorbance for analytes after extraction is higher than that without extraction?

• Because extraction help to minimize the matrix interferences and later preconcentrate the analytes through volume reduction. Hence the concentration increase.

• Because the molar absorptivity of the analytes increase after extraction

• Because extraction increase the chromophore functional groups

• All of the reasons above

Tags

NGSS.HS-PS4-3

What is the wavelength range for visible spectrum of blue color?

• 440-490 nm

• 620-780 nm

• 570 - 585 nm

• 400 - 420 nm

Tags

NGSS.HS-PS4-1

Can B-carotene extracted from carrots be analyzed by UV-Visible spectrophotometry?

• Yes, because it contains conjugated pi electrons

• Yes because it's a cycloalkane

• Yes because it contain halogen groups

• Yes because it is organic analyte

What makes a photometer differs from spectrophotometer

• Photometer uses filters to select wavelength

• Spectrophotometer uses monochromator to select wavelength

• Photometer is cheaper than the other one.

• All of the answers

Why understanding Jablonski Energy Diagram is important in chemical analyses using fluorescence spectrophotometry?

• It helps to understand the selection of absorption and emission wavelengths

• It helps to understand the factors that will diminish/reduce fluorescence intensity

• It illustrate the excited states of a molecule and the radiative and non-radiative transitions that can occur between them

• All of the answers

Tags

NGSS.HS-PS4-5

Choose the WRONG statement about fluorescence spectroscopy

• Simple heterocyclic compounds do NOT fluoresce

• Fused ring heterocycles will fluoresce

• Compounds with high phosphorescence yield will fluoresce

• Substitution of a carbonyl group tends to suppress fluorescence

Why fluorene has higher fluorescence quantum yield value than biphenyl?

• Due to chromophores

• Due to rigid structure

• Due to enhanced internal conversion rate

High _____ will ____ fluorescence quantum yield

• temperature, decrease

• temperature, increase

• temperature, maintain

What is the average lifetime of phosphorescence emission?

• millisecond to minute

• nanosecond to microsecond

• minutes to hours

Phosphorescence spectrophotometer has one extra components as compared to fluorescence spectrophotometer, which is a

• Dewar flask

• monochromator

• radiation source

• detector