5.2,determining glidcose concentration PAG

hello
Basically i am really stuck on the extension questions for this PAG
1. Explain why the transmission of red light increases as the glucose concentration in the sample increases.
2. Why do we centrifuge the sample before taking a colorimeter
3. If the reading for your known glucose solution did not fall whithon your urrve what could you do to obtain an accurate value
SOMEONE PLZZZ HELP ITS IN FOR TOMORROW

Reply 1

Mahquestions

OP

2

Original post by Mahquestions

hello
Basically i am really stuck on the extension questions for this PAG
1. Explain why the transmission of red light increases as the glucose concentration in the sample increases.
2. Why do we centrifuge the sample before taking a colorimeter
3. If the reading for your known glucose solution did not fall whithon your urrve what could you do to obtain an accurate value
SOMEONE PLZZZ HELP ITS IN FOR TOMORROW

SpSOMEONE HELPPPPPPPPPPPPPPPPPP 😡😡😡😡😡😡😡😡😡😡

Reply 2

Hen123456

3

Im not sure if its too late but this is what i put in case its still useful for others1) transmission increases as glucose conc increases because the colour of the solution gets lighter due to increased amount precipitate. More glucose (higher conc) means more precipitate. Lighter liquid lets more light pass through it so the transmission increases2) to filter solution so that solid particles gather and do not disrupt readings. the calorimeter needs to measure the liquid not the particles.3) Extrapolate the data. So like multiply your results by a certain amount then scale it back down again to get an accurate prediction.

Reply 3

Soullesss

1

Yes I know this may be 4 years slightly too late, but could you elaborate on the 3rd point as to how to extrapolate because I'm still kinda unsure.

Reply 4

Student1347962

2

I have the PAG answers from last year if that helps.
1) More glucose means more precipitated Cu2+ which means less dissolved Cu2+ . this means less intensity of blue colouration which indicated that more red light is transmitted.
2) The precipitate must be removed from the sample before colorimetry because any suspended particles will scatter light creating false low transmission on the reading
3) There are several possibilities with this answer.- Easiest one, but least accurate would be to extrapolate the calibration curve.- Creating a dilution series with the unkniwn sample could be suggested guaranteeing that at least one of the dilute samples will fall within the range of the existing calibration curve and the doing the maths to work out the original concentration from that- Creating an extended calibration curve using higher concetrations of known samples would also work.