Can anyone please help with this question on colourimetry? (1 Viewer)

[Modern4DaBois]

Hello, I have a chem depth study on "how to use colourimetry and titration to calculate Keq/Ka"
But I'm kinda confused as to what the blank solution is made from (is the just water?).
Can anyone please provide an example of a colourimetry experiment and what the blank solution to that would be?

Thanks.

 

[jazz519]

Hello, I have a chem depth study on "how to use colourimetry and titration to calculate Keq/Ka"
But I'm kinda confused as to what the blank solution is made from (is the just water?).
Can anyone please provide an example of a colourimetry experiment and what the blank solution to that would be?

Thanks.

Whatever solvent you are using to dissolve the things in. So if you made your solutions by dissolving a substance in water then yeah a blank will just be a sample you take with only water. The purpose of the blank is to account for any background absorption so you should minus that value from all the absorbance values you get for the other solutions with your substance in it

 

[Modern4DaBois]

Whatever solvent you are using to dissolve the things in. So if you made your solutions by dissolving a substance in water then yeah a blank will just be a sample you take with only water. The purpose of the blank is to account for any background absorption so you should minus that value from all the absorbance values you get for the other solutions with your substance in it

Oh ok that makes sense. Thank you so much!

 

[Run hard@thehsc]

@jazz519 would a blank just involve the solvent or would it be everything except the analyte itself (i.e like surroundings cuvette). I read some textbooks which stated that the blank is used so that the absorbance of other substances can be subtracted from that of the analyte, to find a more accurate reading of the analyte itself....

 

[jazz519]

@jazz519 would a blank just involve the solvent or would it be everything except the analyte itself (i.e like surroundings cuvette). I read some textbooks which stated that the blank is used so that the absorbance of other substances can be subtracted from that of the analyte, to find a more accurate reading of the analyte itself....

The blank still means it's run in the cuvette. The cuvette is the sample holder, you cant put the water on the instrument directly

 

[Run hard@thehsc]

Oh ok thank you