Optical rotation of sugars - chirality

Declan Fleming shows us how the optical properties of sugars can be revealed by the use of polarisers.
See the article that accompanies this video in the January 2012 issue of Education in Chemistry magazine - www.rsc.org/Edu...
This is part of the Education in Chemistry Exhibition Chemistry series: chemistry demonstrations to capture your students' imaginations: rsc.li/EiCExChem

[@ola171]

I've learnt for over 6 years that glucose rotates plane polarized light Right and fructose Left but this is the first time I am actually seeing it! Thank you!

[@BHUPINDERSINGH-zo5kd]

I was so confused before but this video made me clear everything Thank you Sir😇

[@appleberry9214]

Whoa. That was cool. Laevo and dextro rotatory stuff. You made it simple to understand. Great job sir. It's a noble work you do right here.

[@Lifesaweb]

thanks for this, you explained this better than my own chemistry teacher

[@mernaromany531]

That's amazing. . I didn't understand now I do
Thanks :)

[@namankarn1504]

i am so happy 'bout discovering this channel.........thank you so much

[@ocayaro]

Great video. Can you say something about how concentrated the solutions should be?

[@declan.fleming]

The more the better. I usually go for a roughly 50:50 mix of sugar to water by volume (as caster sugar) then warm to speed up dissolution. The more concentrated the solution and the longer the distance the light is passing through, the better
Since this video was made I've switched to using a battery operated LED panel as it's getting more and more difficult to get your hands on an OHP. I then page the solutions in sample vials and stand them on top. Students can walk past in smaller classes and look down through the solution. This gives me a long path length so I get a strong effect even if I don't have time to make the most saturated solution

[@peacepeace8164]

You explained it in the way I wanted. Awesome 😇 thank you so much.

[@sarra5802]

u know how time fly it been 11 year since he uploaded this video ,and now i am a first year med student ,if u see this after couples of years bring me back if i am still alife,have a great day and pray for me

[@johnkodhek1]

Great demonstration. I think I'm starting to understand chirality. Thank you.

[@nikolaosvougiouklis6078]

Thank you. I spent a lot of time to see how I could see the rotation of light by sugars.

[@bipinkish]

Where the filter to be placed and moved back and forth?? Please reply dude...

[@declan.fleming]

Light source -> polariser -> sugar solution -> second polariser -> eye
Sorry I didn't see this sooner.

[@rishi_d_mango]

that is a really nice demonstration!!

[@prekshagurung]

:0 that was enthralling truly

[@Milosz_Ostrow]

I'm still no smarter. How is the direction of rotation defined - from the viewpoint of the light source or in the direction of the light source?

[@namankarn1504]

the deflection of the Light from it's original direction

[@Milosz_Ostrow]

+Naman Karn - That's not helpful either, because it doesn't provide a frame of reference. The direction of deflection will vary according to the observer's position relative to the light beam.

[@namankarn1504]

look from the frame of reference of the light source...the deflection of the beam seen from here..would be the direction of rotation

[@declan.fleming]

@@Milosz_Ostrow imagine a skipping rope going up and down (rather than around like in the game) The people moving the rope look down the rope and see motion between the 6 o'clock position and the 12 o'clock. If the light wave is rotated it's like they're now moving their hands diagonally so the rope swings between (for example) between the 2 o'clock and 8.
Does that help? (incidentally this is somewhat of a simplification... physicists will cringe at this description but it's good enough to explain the phenomena in the video)

[@abpm665]

Usefull

[@hermannklein-hessling7612]

Why does the light rotate in the first place?

[@orangeinfotainment620]

very cool

[@ManjeetSingh-be4je]

Nice this video I very love did

[@o73venky]

Steve mould anybody??

[@sasdagreat8052]

Steve Mould + actual need for understanding this for a physics exam here

[@jrntrfanboii]

chemistry confuses me a LOTTTT especially organic chemistry...... nothing makes sense to me I'm just studying it for the sake of clearing my competitive exam and olympiads

[@taureankartik4]

Why the value of sugar solution is different from that of water

[@declan.fleming]

Because the sugar solution has the sugar in it :) water is not chiral so did not rotate plane polarised light.

[@TsubakiRan]

:O That was useful, thank you!

[@Anonymous-rb1bt]

Yeah dude you can't use a retort, you need to put the solute directly between the two. Like a sammich

[@arjunshamsunder5389]

=O in my textbook, it's given that sucrose rotates to the left !

[@rengoku3658]

Mix glucose and fructose and form resimic solution and then pass ppl through it 😊

[@Aaron11801]

Flemistry

[@sambreena]

Good video and very much explained in it

[@ponnilavan3709]

Poga pinda

[@user-pj2xd8uo6b]

why does he look like a killer

[@wholeloteditz2228]

😂