Spectrophotometer

You want to measure the absorbance of a DNA sample. What type of spectrophotometer would you use?

• UV spectrophotometer

• Visible light spectrophotemeter

• MRI

• Mass spectrometer

Objects appear to be different colors to our eyes because we see:

• Light that is reflected by the object

• Light that is absorbed by the object

• Infrared light

• Ultraviolet light

Of the steps listed, which would you do first?

• Allow the Spec to warm up per manufacturer's instructions

• Wipe the blank cuvette to remove fingerprints

• With the cuvette removed, set the absorbance to 0

• Insert the blank cuvette and calibrate the spec.

When preparing a blank, how do you choose the correct liquid?

• Use the same liquid that is mixed with your substance of interest.

• Use ethanol for proteins and water for starches.

• Use distilled water whenever possible.

• Use methanol whenever it is available.

What is the purpose of creating a standard curve?

• It allows you to determine the concentration of an unknown solution.

• It allows you to estimate the absorbance of a substance with a known concentration.

• It provides you with the entire absorption spectrum of a substance.

• It allows you to determine what chemical elements are present in a solution.

If a substance is colored when you observe it, what type of spectrophotometer will you most likely use?

• UV spectrophotometer

• Visible light spectrophotemeter

• MRI

• Mass spectrometer

What are some steps to follow when preparing a standard curve?

• Measure several samples of known dilution at one specific wavelength and plot their absorbance on a graph vs. concentration. Then add a line of best fit.

• Measure two samples of known dilution at one specific wavelength and plot their absorbance on a graph vs. concentration. Then add a line of best fit.

• Measure several samples of known dilution at many wavelengths and plot their absorbance on a graph vs. concentration. Then add a line of best fit.

• Measure several samples of known dilution and then use a line of best fit to determine their wavelength.

Optimally, where should your unknown concentrations fall in your standard curve?

• Close the midpoint between your know concentrations.

• To the right of your highest data point.

• To the left of your lowest data point.

• When possible, above the line of best fit.

A spectrophotometer can be used to (check all that apply):

• determine the presence of a substance in a solution.

• measure the concentration of an unknown solution.

• determine the molecular composition of an unknown substance.

• identify an unknown substance

The amount of light absorbed by a sample is called its:

• Absorbance

• Transmittance

• Hue

• Saturation

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-3

NGSS.HS-PS4-4