Exp 9

Question 1

How do we measure the absorbance is a standard solution?
What does a standard solution mean ?

Answer 1

Using the spectrophotometer .
A solution with known concentration

Question 2

How do we dilute the standard solutions added to the flasks?

Answer 2

By adding distilled water

Question 3

What is the rule of dilution ?

Answer 3

M st V st = M dil V dil
Where both of the properties of the substance can be measured with any unit as long as it is the same on both sides of the equation

Question 4

What technique does spectrophotometery uses ? And what does it determine?

Answer 4

It uses the absorbance of light by an analyze at a certain wavelength
It determine the concentration of the analyte

Question 5

What is the difference between the
Spectrophotometer and the UV\Vis spectrophotometer ?

Answer 5

Spectrophotometer uses all light

UV\Vis spectrophotometer uses ultra-violet / visibility light of the electromagnetic spectrum

Question 6

What is the spectophotometer used for?

Answer 6

It is used to measure the amount of light transmitted around absorbed

Question 7

What is the visibility range?

Answer 7

It is the range of wavelength that the human eye Ann see: 400nm to 700nm

Question 8

What happens when light hits the colored solution?

Answer 8

Excitation of electrons
The electrons move from the ground state( level ) to the existing state( level) showing the absorbance of the light

Question 9

What are the steps of spectrophotometer?

Answer 9

1- from the light source ( tungsten ) the light bulb emit the white light . Then the light go through a monochromator.
2- the monochromator separates the white light into multiple colors. The monochrome tear can be a prism of=r a grating
3- photocell the light reaches the photomultiplier which messers the wave length of the light

Question 10

What color is seen?

Answer 10

What ever the color of light was absorbed the lite seen will be the opposite in the color circle

Question 11

What color is absorbed to see viloet ? And what its wavelength?

Answer 11

Yellow green
400-430nm

Question 12

What is beer’s law ?

Answer 12

Absorbance and concentration are directly proportional

Question 13

What is lambert’s law?

Answer 13

Absorbance and pathway are directly proportional

Question 14

Who’s law describe the relashinship between
A) absorbance and pathway
B) absorbance and concentration

Answer 14

A) lambert’s
B) beer

Question 15

What id the beer- lamberts law?

Answer 15

A= exeleration I C
Where
A is the absornbance | without a unit
I is the pathlength |cm
C is the analyte concentration | mol\ L( the same as the molarity )
E= is the molar absorptivity | L\mol . Cm

Question 16

So What Should We Do To Remove Other Compound Absorbance?

Answer 16

By using blank

Question 17

How to find the molar absorptivity?

Answer 17

From the calibration curve( beers law| absorbance and concentration ) we find the liner equation y=mx+c and solve for m , where m is the molar absorptivity.