COLOURIMETRY Flashcards
What is a colorimeter
It’s a light-sensitive device used for measuring the transmittance and absorbance of light passing through a liquid sample
whats the difference between transmittance and absorbance of light
absorbance is how much light the sample absorbed and transmittance is the amount of light that passes through the sample that doesn’t get absorbed
list the 7 components of colorimetry
- light source
- collimator (lens)
- monochromator
- wavelength selector (slit)
- sample solution
- detector (photocell)
- digital display or meter
what is the role of the light source
provides light to pass through the sample
what is the role of the collimator
converts parallel waves of light to a beam that focusses into the monochromator
what is the role of the monochromator
divides light into distinct wavelengths and selects the specific wavelength to pass through the sample
what is the role of the cuvettes
they contain the sample solution
what is the role of the detector (photocell)
when light falls into the detector, it generates an electric signal which is then reflected as a reading in the galvanometer
what is the role of a digital display
converts electric signals into readings that correspond to the intensity of light that’s displayed as a numerical value on the screen
outline how colorimetry work
- a beam of light with a specific wavelength chosen by the monochromator is passed through the sample solution
- the light that doesn’t get absorbed reaches the detector
- the device analyses the colour compared to an existing standards
- microprossecor then calculates the absorbance or percent transmittance
list five industry colourimetry is used in
- agriculture
- water testing
- colour printing
- textile manufacturing
- painting manufacturing
what is the function of colourimetry in agriculture
determine conc. of plant nutrients
what is the function of colourimetry in water testing
testing water quality by screening chlorine and fluoride
what is the function of colourimetry in colour printing
calculate recommended adjustment for ink zones
what is the function of colourimetry in textile manufacturing
colour matching, quality control in fabric production etc
what is the function of colourimetry in paint manufacturing
control colour difference problem
what is beer-lambert’s law
- A higher absorbance indicates that more light has been absorbed and less light has passed through the sample.
- absorbance is directly proportional to concentration and path length.
in a flow chart what do the following symbols mean:
- oval
- arrows
- parallelogram
- rectangle
- diamond
- start/end
- shows relationship between shapes
- input/output
- process
- decision
what colour is copper solution
blue
why is copper dangerous
- heavy metal pollutant in the enviro
- toxic to living organisms including humans
- excess levels of copper can cause illness
what is the inquiry question you developed in the depth study
“how can colourimetry be used to determine the concentration of copper ions in an unnown solution”
What is the hypothesis you developed in the depth study
“If the absorbance of known concentration of copper (2) sulfate are known, then we can use Beer-Lambert’s Law to determine the concentration of unknown copper(2) sulfate”
risk assessment of copper(2) sulfate
- if in contact with skin can cause irritation
how is copper(2) sulfate disposed in a practical
waste beaker
what is a controlled variable in colourimetry
the volume of prepared solution
using the colour wheel, which colour of light will be absorbed the most by a solution
the colour on the opposite side of the wheel to itself.
eg. if the solution is blue it will absorb mainly orange wavelengths
what is the formula for percentage error
[actual - experimental]/actual x 100
