Unit 2 Quiz Flashcards
spectrophotometry
allows you to measure the absorbance and transmittance of light energy by molecules.
Absorb
When light of specific wavelength (color) is passed through a solution, some of the light energy will be absorbed.
Transmit
The remaining light energy that is not absorbed when passed through a solution, is detected and expressed on a meter as either percent transmittance (%T) or absorbance (A).
Spectrophotometer
Mode button Digital display Wavelength knob Sample holder 0% T-Knob 100% T Knob Filter switch
6 Colors of visible light
Red Orange yellow green blue violet
measured in nanometers (nm)
Red
620-750 nm
Orange
590-620 nm
Yellow
570-590 nm
Green
500-570 nm
Blue
450-500 nm
Violet
380-450 nm
Electromagnetic Radiation
Visible light is part of a large field of energy that is known as electromagnetic radiation
All energy travels through space in a pattern called
waves
smaller wavelengths=
higher energy
larger wavelengths=
lower energy
If an object is red then the white light is hitting it and all the colors but red are being
absorbed but the red light is being transmitted.
which color of visible light has the highest energy level?
violet
Examples of electromagnetic radiation
microwaves x-rays gamma rays UV light TV radio
A spectrophotometer can be utilized to
determine the concentration of a solution using a set of standards of known concentration.
A higher concentration means
a larger amount of light will be absorbed.
Visible light is only a
small portion of a broad spectrum of available energy called electromagnetic radiation.
Electromagnetic Radiation travels in the form of a
wave, with the distance between two crests termed a wavelength.
Visible light consists of light wavelengths from approximately
380-720 nanometers.
Shorter wavelengths have
higher frequency and higher associated energy.
The mode button
is the left button on the top and it switches between the absorption and transmittance modes.
The Wavelength control knob
is the circular knob on the right side in the middle part of the spectrophotometer. The wavelength knob is used to change the wavelength.
The 100% T Knob
is the circular knob on the right side of the bottom part of the spectrophotometer. It is under the wavelength knob. The 100% T knob controls how much transmittance (or brightness).
The 0% T Knob
is the circular knob on the left side of the spectrophotometer on the bottom part. It is to the left of the 100% T knob. The 0% T knob is used to turn the spectrophotometer off and on, and controls the zero control.
The Sample Holder
is on the left side on the middle part of the spectrophotometer. You place the test tubes in there.
The Filter Switch
is on the left side on the bottom kind of underneath the spectrophotometer.
The Digital Display
is on the top part of the Spectrophotometer on the left side next to the mode button. It shows the wavelength, absorbance, transmittance, and a few other things?
