Measuring Light Interactions with a Spectrophotometer

The video tutorial explains how a spectrophotometer measures the interaction of light with a sample. It details the operation of the device, including the role of the lamp, diffraction grating, and detector. The tutorial then guides viewers through an experiment to determine the absorbance spectrum of red food coloring, demonstrating how to set up the device, measure transmittance and absorbance, and record results. By following these steps, viewers can plot the absorbance spectrum and gain practical experience with the spectrophotometer.

What is the primary function of a spectrophotometer?

• To measure the effect of a sample on a beam of light

• To measure the temperature of a sample

• To measure the weight of a sample

• To measure the sound emitted by a sample

What component of the spectrophotometer separates light into its component wavelengths?

• The sample chamber

• The detector

• The lamp

• The diffraction grating

What does the detector in a spectrophotometer measure?

• The color of the sample

• The weight of the sample

• The temperature of the sample

• The transmittance and absorbance of the sample

What is the first step in the experiment to determine the absorbance spectrum of red food coloring?

• Adjust the display to 100% transmittance

• Press the mode control key

• Place the sample in the chamber

• Set the wavelength to 380 nanometers

What is the purpose of using a blank cuvette in the experiment?

• To clean the sample chamber

• To ensure the sample is at the correct temperature

• To measure the absorbance of the sample

• To calibrate the spectrophotometer to 0% transmittance

What is the absorbance of the sample containing red food coloring at 380 nanometers?

• 7.4%

• 0.845

• 1.130

• 14.2%

At 405 nanometers, what is the transmittance of the sample?

• 1.130

• 14.2%

• 0.845

• 7.4%

What should you do after increasing the wavelength by 25 nanometers?

• Turn off the spectrophotometer

• Change the sample

• Wipe the blank cuvette and adjust to 100% transmittance

• Record the temperature

What is the final wavelength mentioned for plotting the absorbance spectrum?

• 680 nanometers

• 380 nanometers

• 455 nanometers

• 405 nanometers

What is the purpose of plotting the absorbance spectrum?

• To measure the sound emitted by the sample

• To understand how the sample interacts with different wavelengths of light

• To find the temperature of the sample

• To determine the weight of the sample