its yr 12 chemistry doing testing for cellulose, starch etc
The dark blue positive with schultz's soln on cellulose, and the Iodine /KI solution black positive on starch. Can anyone provide the reaction equation for these please?
Thanking you
reaction equation: schultz's & I/KI soln starch cellulose
- Ocean Breeze
- Posts: 798
- Joined: 01 Jun 2006, 10:00
- Job Title: Lab Manager
- State/Location: NSW
- DavidPeterson
- Posts: 196
- Joined: 02 Apr 2012, 12:19
- Job Title: STEM Resource & Lab Manager
- School: Murray Bridge High School
- Suburb: Murray Bridge
- State/Location: SA
Re: reaction equation: schultz's & I/KI soln starch cellulos
Do you make your own Schulz solution or do you purchase it? I have been asked for this over the years, and the formulation I found on the 'net never seems to give positive results.
With respect to the starch / Iodine reaction: the best anyone (including Dr Karl Kruszelnicki) has ever been able tyo tell me is that a starch-iodine complex is formed.
With respect to the starch / Iodine reaction: the best anyone (including Dr Karl Kruszelnicki) has ever been able tyo tell me is that a starch-iodine complex is formed.
DCP
STEM Resource @ Laboratory Manager
RPAS (Drone) Pilot
STEM Resource @ Laboratory Manager
RPAS (Drone) Pilot
- Graham Kemp
- Posts: 173
- Joined: 22 Nov 2011, 09:21
- Job Title: Laboratory Assistant
- School: St John's School
- Suburb: Roma
- State/Location: QLD
Re: reaction equation: schultz's & I/KI soln starch cellulos
Yeap. That's basically all it is to it.
Starch forms a tightly coiled spring in solution (almost torus-, or donut-, shaped).
The linear triiodide ion ( I3- ) slips neatly into this coil to form an ionic complex; in which position its vibrations are constrained. Thus causing its change in absorbance ( a colour change ).
Starch forms a tightly coiled spring in solution (almost torus-, or donut-, shaped).
The linear triiodide ion ( I3- ) slips neatly into this coil to form an ionic complex; in which position its vibrations are constrained. Thus causing its change in absorbance ( a colour change ).
- Ocean Breeze
- Posts: 798
- Joined: 01 Jun 2006, 10:00
- Job Title: Lab Manager
- State/Location: NSW
Re: reaction equation: schultz's & I/KI soln starch cellulos
Thanks Graeme. Perfect Just what I needed
David, I make my own schultz
Zn Cl sat soln then cooled.
The add drop by drop the I/KI soln
David, I make my own schultz
Zn Cl sat soln then cooled.
The add drop by drop the I/KI soln
- DavidPeterson
- Posts: 196
- Joined: 02 Apr 2012, 12:19
- Job Title: STEM Resource & Lab Manager
- School: Murray Bridge High School
- Suburb: Murray Bridge
- State/Location: SA
Re: reaction equation: schultz's & I/KI soln starch cellulos
Graham Kemp wrote:Yeap. That's basically all it is to it.
Starch forms a tightly coiled spring in solution (almost torus-, or donut-, shaped).
The linear triiodide ion ( I3- ) slips neatly into this coil to form an ionic complex; in which position its vibrations are constrained. Thus causing its change in absorbance ( a colour change ).
Thanks for the description of the mechanism...it's something that I have asked many people over the years. Should have contacted my universtity organic chem lecturer (I think he's still alive...)
DCP
STEM Resource @ Laboratory Manager
RPAS (Drone) Pilot
STEM Resource @ Laboratory Manager
RPAS (Drone) Pilot