# Colorimeter Help!

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#1
hi everyone!! iv jus read in a txt book that when using a colorimeter on a solution of reducing sugar (with benedicts reagent added to it) , u need a red light filter to act as a "0" .. the txt book didnt really elaborate on this soo im not quite sure what the purpose of a red filter would be? -

it does say a bit after that iv u plotted a graph the transmission would increase as reducing sugar content increases -

soo would tat mean that using a red filter on a colorimeter with a red solution sample inside- would give 100% transmission? and as the solutions decreace (red-orange-yellow-green-blue) the transmision tends towards the direction 0% ??

can someone please explain to me what transmission and absorbance is - aswell !! thanks soo much everyone!!
2
11 years ago
#2
(Original post by Ammar21)
hi everyone!! iv jus read in a txt book that when using a colorimeter on a solution of reducing sugar (with benedicts reagent added to it) , u need a red light filter to act as a "0" .. the txt book didnt really elaborate on this soo im not quite sure what the purpose of a red filter would be? -

it does say a bit after that iv u plotted a graph the transmission would increase as reducing sugar content increases -

soo would tat mean that using a red filter on a colorimeter with a red solution sample inside- would give 100% transmission? and as the solutions decreace (red-orange-yellow-green-blue) the transmision tends towards the direction 0% ??

can someone please explain to me what transmission and absorbance is - aswell !! thanks soo much everyone!!
you use a red filter because its the complementary colour to blue - benedicts absorbd blue light and transmits red so you can test the benedicts solution concentration as less concentrated = less blue absorbed

yup using a red filter with red solution would transmit all red light so would be useless for a red solution, for red solutions you use a blue filter.

transmission is basically used in the same context as reflection - transmission is the way the solution allows light through or reflects it and so this is the colour the solution appears
absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see

when using a colorimeter you test absorbance as absorbance of a coloured light (of the complementary colour to the solution) decreases as solution becomes less concentrated

5
11 years ago
#3
(Original post by colourful)
you use a red filter because its the complementary colour to blue - benedicts absorbd blue light and transmits red so you can test the benedicts solution concentration as less concentrated = less blue absorbed

yup using a red filter with red solution would transmit all red light so would be useless for a red solution, for red solutions you use a blue filter.

transmission is basically used in the same context as reflection - transmission is the way the solution allows light through or reflects it and so this is the colour the solution appears
absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see

when using a colorimeter you test absorbance as absorbance of a coloured light (of the complementary colour to the solution) decreases as solution becomes less concentrated

3
4 years ago
#4
What about a copper (II) sulfate which is blue
0
4 years ago
#5
What about a copper (II) sulfate which is blue because I'm talking about a colorimetry method
0
9 months ago
#6
Sorry to point it out, but as you caused headache for me with your sentences I want to help others by reflecting on your mistakes.If you say that absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see...which is right, then you cannot claim that Benedict's solution absorbs blue, because then why on earth we see it blue?!The correct is: Benedict's solution absorbs red, and reflects/transmits blue.You use red lens in colorimeter. At the beginning (without heating, the colour is blue) the absorbance level will be high (the blue coloured solution absorbs all the used red wavelengths).As the glucose concentration increases less Benedict's solution (blue) is present (because it became reduced hence changed its colour to reddish) so less red light can be absorbed, the transmission level increases.
0
9 months ago
#7
Sorry to point it out, but as you caused headache for me with your sentences I want to help others by reflecting on your mistakes.If you say that absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see...which is right, then you cannot claim that Benedict's solution absorbs blue, because then why on earth we see it blue?!The correct is: Benedict's solution absorbs red, and reflects/transmits blue.You use red lens in colorimeter. At the beginning (without heating, the colour is blue) the absorbance level will be high (the blue coloured solution absorbs all the used red wavelengths).As the glucose concentration increases less Benedict's solution (blue) is present (because it became reduced hence changed its colour to reddish) so less red light can be absorbed, the transmission level increases.
0
9 months ago
#8
(Original post by colourful)
you use a red filter because its the complementary colour to blue - benedicts absorbd blue light and transmits red so you can test the benedicts solution concentration as less concentrated = less blue absorbed

yup using a red filter with red solution would transmit all red light so would be useless for a red solution, for red solutions you use a blue filter.

transmission is basically used in the same context as reflection - transmission is the way the solution allows light through or reflects it and so this is the colour the solution appears
absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see

when using a colorimeter you test absorbance as absorbance of a coloured light (of the complementary colour to the solution) decreases as solution becomes less concentrated

Sorry to point it out, but as you caused headache for me with your sentences I want to help others by reflecting on your mistakes.If you say that absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see...which is right, then you cannot claim that Benedict's solution absorbs blue, because then why on earth we see it blue?!The correct is: Benedict's solution absorbs red, and reflects/transmits blue.You use red lens in colorimeter. At the beginning (without heating, the colour is blue) the absorbance level will be high (the blue coloured solution absorbs all the used red wavelengths).As the glucose concentration increases less Benedict's solution (blue) is present (because it became reduced hence changed its colour to reddish) so less red light can be absorbed, the transmission level increases.
2
1 month ago
#9
(Original post by Csilla555)
Sorry to point it out, but as you caused headache for me with your sentences I want to help others by reflecting on your mistakes.If you say that absorbance is the light wavelengths absorbed by a solution so they do not contribute to the colour we see...which is right, then you cannot claim that Benedict's solution absorbs blue, because then why on earth we see it blue?!The correct is: Benedict's solution absorbs red, and reflects/transmits blue.You use red lens in colorimeter. At the beginning (without heating, the colour is blue) the absorbance level will be high (the blue coloured solution absorbs all the used red wavelengths).As the glucose concentration increases less Benedict's solution (blue) is present (because it became reduced hence changed its colour to reddish) so less red light can be absorbed, the transmission level increases.
So my solution (Different experiment) gradually turns red as the concentration increases. At the beginning it is COLOURLESS. And I used to blue light filter at the beginning. For some reason. (yes, colourimeters are leaving me very confused) So my absorbance read DECREASED as the colour of red got DARKER. Is that correct? So when it's at distilled water the absorbance was 0. And then it spiked to 0.25. Then from then, it decreased. Did I do something wrong?
0
4 weeks ago
#10
Guys this thread is 11 freaking years old
0
4 weeks ago
#11
(Original post by tbi_zlx)
Guys this thread is 11 freaking years old
Yeah.It's crazy innit how a post 11 years ago helps me understand the school content now.
Last edited by Fair2Cloud7; 4 weeks ago
1
4 weeks ago
#12
(Original post by Fair2Cloud7)
Yeah.It's crazy innit how a post 11 years ago helps me understand the school content now.
Im ngll this is sooo tru when I was in a levelsss
1
4 weeks ago
#13
(Original post by tbi_zlx)
Guys this thread is 11 freaking years old
Didn't even realise, damnnn.
The people who created the thread are probably so old now.
1
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