| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| lipebcampos | " I tried to access open2study, but the site is not offering courses anymore. This search tool helped me find courses https://classpert.com " | Read more » | over 5 years ago | |||
| rahamath_prizm | " So good to know it got identified soon. passive income " | Read more » | about 6 years ago | |||
| straylight | " thanks solaris, yes, the yeast, like the sugar, has bolted. An analytical test for red and white wine, excellent, we are making progress :) Agre..." | Read more » | about 6 years ago | |||
| solaria | " Thanks Stray'. Actually, the 0.06 A for the wine was at 5 cm path. Divide by 5 to get 1 cm path for comparison. If yeast/fermentation was cont..." | Read more » | about 6 years ago | |||
| straylight | " solaria, great work, much kudos deserved. A rigorous experiment. Like david_uwi, I wondered at why sucrose is absorbing visible light (VL) at all..." | Read more » | about 6 years ago | |||
| solaria | " Well, the sucrose absorbance is very low, but it's not zero. See Sucrose Absorbance. Since the data is 'clean' and the calculations match expec..." | Read more » | about 6 years ago | |||
| david_uwi | " Problem I have is that sucrose solution looks colorless so does not absorb visible light. I feel that the changes in absorbance that you are seein..." | Read more » | about 6 years ago | |||
| solaria | "Here’s my try at this experiment. Basically, Yes, you can detect added sugar in wine, but it’s a very small change, and requires an accurate basel..." | Read more » | about 6 years ago | |||
| 34zhijian | "Hi, how does one download the data in the appendix? Thanks! " | Read more » | over 6 years ago | |||
| warren | "Related: How can we detect contaminants in water samples with a DIY spectrometer using reagents? https://publiclab.org/notes/warren/12-18-2017/ca..." | Read more » | about 7 years ago | |||
| warren | "Also noting that @ygzstc cited some work supporting the use of the area under the curve in a spectrum data reading instead of intensity at one wave..." | Read more » | about 7 years ago | |||
| warren | "Just to clarify here, I believe to sum up we can say that: IF a reagent reacts linearly (for example, if doubling the concentration of the thing t..." | Read more » | about 7 years ago | |||
| warren | "Copying in answer from @stoft, here: It is my understanding that Beer's law is not the relationship between reagent's effect on color, but is the ..." | Read more » | about 7 years ago | |||
| straylight | "thanks ygzstc, that makes sense. I think that the approximation that relative intensity measured from the scope can be used in place of the log rel..." | Read more » | almost 9 years ago | |||
| ygzstc | "Yes the Beer-Lambert Law is based on -log(I/Io) but it's applicable for a single wavelength value. (https://en.wikipedia.org/wiki/Beer%E2%80%93Lamb..." | Read more » | almost 9 years ago | |||
| warren | "It's odd -- I see the graphs. Straylight, can you contact web@publiclab.org so we can figure out what's going on there? " | Read more » | almost 9 years ago | |||
| straylight | "Thanks for the question. My apologies that all of the graphs appear to have vanished (they have for me). Not sure why, maybe a hosting issue. Anyw..." | Read more » | almost 9 years ago | |||
| anjohn12 | "Quick question, I'm trying to do something similar for a school project. Shouldn't the absorbance of the sample be the negative log of the percent ..." | Read more » | almost 9 years ago | |||
| msysinfo | "I need to measure oil concentration in a water mixture. Can a SPECTROMETER be used to measure the oil concentration? If it a solute that dissolves ..." | Read more » | about 9 years ago | |||
| breadytoroll | "@homechemist what is this "multi range LED" you refer to? I did a quick search online that didn't turn up any continuously varying LED's, could you..." | Read more » | over 9 years ago | |||
| warren | "Wow, @homechemist just posted a great update, here: http://publiclab.org/notes/homechemist/06-12-2015/the-importance-of-infrared-radiation-infrared..." | Read more » | over 9 years ago | |||
| straylight | "Good points and I understand how you feel, coming at his from a chemistry teachers viewpoint myself. I guess it depends on what experiments and dem..." | Read more » | almost 10 years ago | |||
| srpratt | "I'm new to the cellphone-becomes-a-photospec phenomenon, as I was told about this by a colleague. As an AP Chem teacher, I'm looking for hacks to ..." | Read more » | almost 10 years ago | |||
| ichinarayan | "ok thanks so much " | Read more » | about 10 years ago |