Great video on the Winkler method! Thank you very much. I've worked the link into my lab-class and am encouraging my students to watch it. Far-out lab coat btw :)
An easier way to find the endpoint would be to use starch as an indicator. It's much easier to see a change from black-colourless than yellow-colourless
haha.. very accurate scientific measurements you have right there! 10 drops of titre ! Love to see you work out the concentration of DO from that! Good tutorial though!
This and all of your other videos are excellent, and I am using them for studying in biology class. I noticed that after you poured the sodium thiosulfate into the solution, I observed grains of the sodium thiosulfate on the inside wall of the bottle where the stopper goes. Wouldn't that produce an air bubble and affect the test?
when the acid is added it stops any oxygen from reacting with the components in the flask (probably Mn(OH)2 or the like - atleast in winkler method) by stopping the reaction (due to pH changing and OH- ions originally present due to basic conditions shift equilibrium to H+ and acidic conditions). The precipitate formed is the only thing that reacts with the H+, from acid, and releases the iodine (I2) which changes the colour. Note: my answer comes purely from intuitive thinking! Please correct me if Im wrong :D
The mgso4 and alkaline iodide react form mg(oh)2 which in turn react all the oxygen present in water to form mg(oh)3 so the first two step should be done quickly so to prevent oxygen in or out from the bottle
Great video on the Winkler method! Thank you very much. I've worked the link into my lab-class and am encouraging my students to watch it. Far-out lab coat btw :)
Nice job Mr.Anderson!
An easier way to find the endpoint would be to use starch as an indicator. It's much easier to see a change from black-colourless than yellow-colourless
haha.. very accurate scientific measurements you have right there! 10 drops of titre ! Love to see you work out the concentration of DO from that!
Good tutorial though!
just watched all the labs! thank you so much for this! :)
Your students are very lucky to have such a wonderful teacher. Is there a site online you can buy that dissolved oxygen kit?
I want your lab coat so very badly.
Thank you Sir
you were really helpful i got an A in bio
thanx for the help!!!!
Why does the flocc need to settle twice?
thank u so much
Why not added starch indicator? Please clarify
what are the conclusions for this lab?
This and all of your other videos are excellent, and I am using them for studying in biology class. I noticed that after you poured the sodium thiosulfate into the solution, I observed grains of the sodium thiosulfate on the inside wall of the bottle where the stopper goes. Wouldn't that produce an air bubble and affect the test?
when the acid is added it stops any oxygen from reacting with the components in the flask (probably Mn(OH)2 or the like - atleast in winkler method) by stopping the reaction (due to pH changing and OH- ions originally present due to basic conditions shift equilibrium to H+ and acidic conditions). The precipitate formed is the only thing that reacts with the H+, from acid, and releases the iodine (I2) which changes the colour.
Note: my answer comes purely from intuitive thinking! Please correct me if Im wrong :D
The mgso4 and alkaline iodide react form mg(oh)2 which in turn react all the oxygen present in water to form mg(oh)3 so the first two step should be done quickly so to prevent oxygen in or out from the bottle
Im taking ap bio next year
Do I have to wear headphones that make me look funny to do the DO lab.....also how do you talk without a head? Other than that you are amazing!!!!!
Guys, could anyone let me know what is the ionic charge of the dissolved oxygen?
dear sir. may you tell us which ASTM you use it?
anyone else start looking for a chat box when the video makes that little pop sound?
Where do I get that test kit from
The third chemical which he added was sulphuric acid or sulfamic acid correct me plz
Fun
Hands don't talk! Lol :D