Hi All,
A prac order asks for starch solution (fairly dilute). Can anyone help me with how 'fairly dilute' is 'fairly dilute in reducing sugars prac'? 0.5%? more? less?
Thanks in advance,
Rita
Reducing Sugars
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- Posts: 829
- Joined: 15 Dec 2015, 10:49
- Job Title: Lab Technician
- School: FCAC
- State/Location: QLD
Re: Reducing Sugars
My Chem teacher askes for 0.01% ....it will still give a dark blue result with an Iodine test
He was saying the regular 1% starch solution was a giveaway compared to the clear Glucose and Sucrose solutions
He was saying the regular 1% starch solution was a giveaway compared to the clear Glucose and Sucrose solutions
Re: Reducing Sugars
Teacher was talking about 5% for sucrose and glucose solutions. Can they be lower also?
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- Posts: 829
- Joined: 15 Dec 2015, 10:49
- Job Title: Lab Technician
- School: FCAC
- State/Location: QLD
Re: Reducing Sugars
Thanks Rita...just got excited
We normally use 1% Sucrose and glucose solution but the Chem teacher said that the Sucrose should break down to Glucose at close to 100 degC but he could never get it to work .
Just knocked up a few beakers of 5% 1% and 0.2% Sucrose and glucose and stuck them on the hot plate with Benidicts
All the Glucose changed colour at around 70 DegC ...even the 0.2% sample but it took a lot longer .
The 5% Sucrose solution Did noticeably change colour at around 95 deg C...nothing as spectacular but Noticable .
The 1% and 0.2% Sucrose did nothing .
Thanks again Rita ...You solved a puzzle . I might make my Chem teacher happy next time they do this .
Yeah the reason he likes the Starch so diluted is so the three all look the same , otherwise the Kids immediately recognise the starch as the cloudy one .
Now the prep room smells like Toffee
We normally use 1% Sucrose and glucose solution but the Chem teacher said that the Sucrose should break down to Glucose at close to 100 degC but he could never get it to work .
Just knocked up a few beakers of 5% 1% and 0.2% Sucrose and glucose and stuck them on the hot plate with Benidicts
All the Glucose changed colour at around 70 DegC ...even the 0.2% sample but it took a lot longer .
The 5% Sucrose solution Did noticeably change colour at around 95 deg C...nothing as spectacular but Noticable .
The 1% and 0.2% Sucrose did nothing .
Thanks again Rita ...You solved a puzzle . I might make my Chem teacher happy next time they do this .
Yeah the reason he likes the Starch so diluted is so the three all look the same , otherwise the Kids immediately recognise the starch as the cloudy one .
Now the prep room smells like Toffee
Re: Reducing Sugars
Thanks bigmack you explained what I didn't know.