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Simply because we cannot measure light absorbed. We are, however, able to measure light transmitted through the use of a spectrophotometer. The device works by shining light of a specific wavelength on a substance and measuring the amount of light that gets through. This "transmittance" has a negative logarithmic relationship to absorbance.
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Why should the y intersect of any Beer's law plot equal zero?
Beer's law says that absorbance is directly proportional to concentration. So if there is zero concentration there should be zero absorbance (0,0).
What is difference between specific absorbance and absorbance interms of spectroscopy?
specific absorbance- it is absorbance in a solution containing one gm of substance in 100 ml solvent in 1cm shell. so it is having a difference with absorbance which is negative logarithm of incident light to the transmitted light. divya.chakraborty@gmail.com
Can Energy be measured directly with a calorimeter?
Yes energy can be measured directly with a calorimeter. The calorimeter will measure the temperature as it changes in a reaction.
Which quantity is directly measured in a titration?
volume
What is analytical wavelength?
Absorbance maximum
Why is absorbance plotted instead of percent transmission when following bacterial growth?
Because when we read absorbance, it's the amount of light absorbed by the bacteria itself. Absorbance is directly related to the amount of bacteria. More absorbance = more bacteria.
Can a turbid sample be measured for absorbance in UV spectrophotometer?
Yes. Olis, Inc. (Bogart, GA) offers the CLARiTY line of spectrophotometers, which are specifically designed to give accurate absorbance readings in highly turbid samples.
In a plot of absorbance vs concentration what does the slope represent?
The slope of absorbance vs concentration reptresents the value of εb, where ε is the absorbtivity with units of (L/mol cm) and b is path length measured in cm.
What is e-value of a optical brightening agent?
e-value of an optical brightening agent is the absorbance value obtained (in the UV region), when the absorbance of 1% solution is measured using a cuvette of 1 cm path length. T.J.R.PILLAI
Why should the y intersect of any Beer's law plot equal zero?
Beer's law says that absorbance is directly proportional to concentration. So if there is zero concentration there should be zero absorbance (0,0).
What is blank in spectrophotometer?
A blank is used in order to cancel out or zero the absorbance of all the other components in the sample except the component whose absorbance is to be measured. For example, if you want to measure the absorbance of a solute in water, you will use only water as a blank and the spectrophotometer will subtract the absorbance of water from the spectrum when you measure the absorbance of your solute in water.
Is wavelength or absorbance the dependent variable?
"absorbance"Since in the experiment, you probably choose the wavelength, then measure the absorbance (absorption?, the absorbance is the dependent variable.
What is the purpose of the blank?
Blank Sample in Spectrophotometry is used to measure the absorbance of light without sample. It is subtracted from the total absorbance for measurement of Absorbance from a sample's absorbance.
How is gravitational potential energy measured?
It is calculated, not directly measured.
What is difference between specific absorbance and absorbance interms of spectroscopy?
specific absorbance- it is absorbance in a solution containing one gm of substance in 100 ml solvent in 1cm shell. so it is having a difference with absorbance which is negative logarithm of incident light to the transmitted light. divya.chakraborty@gmail.com
What is the different between primary absorbance and secondary absorbance in fluorescence?
in primary light absorbed by outer molecule while in secondary re-absorbance occurs
What do you call the type of unit that can be measured directly?
There is no specific name. This is partly because derived units, such as volume, can be measured just as directly as lengths.
