# Tag Info

4

You got the solubility part reversed. The solubility of $\ce{AgCl}$ is lower than the solubility of $\ce{Ag2CrO4}:$ $$s(\ce{AgCl}) = \sqrt{K_\mathrm{sp}(\ce{AgCl})} = \sqrt{\pu{1.8E-10 mol2 L-2}} = \pu{1.34E-5 mol L-1}$$ $$s(\ce{Ag2CrO4}) = \sqrt[3]{\frac{K_\mathrm{sp}(\ce{Ag2CrO4})}{4}} = \sqrt[3]{\frac{\pu{1.1E-12 mol3 L-3}}{4}} = \pu{6.50E-5 mol L-1}$$ ...

3

There is a famous saying that paper never refused an ink, which means anyone can write anything on the paper and the paper won't say anything back to the writer. Internet has made this situation worse. One should develop a healthy level of skepticism when reading website and forums. Why is copper the only transition element to give a coloured flame? Most ...

3

Citric acid has $\mathrm{p}K_\mathrm{a}$-values of 3.1, 4.7, and 6.4, while those of tartaric acid are 3.0 and 4.3. If you adjust the $\mathrm{pH}$ to 6.4, tartaric acid would be roughly 100% deprotonated, while 50% of citric acid still has one proton to give off. If you titrate this solution with $\ce{NaOH},$ you could estimate the buffer capacity, giving ...

2

The title of the question is about sample heating by ED-XRF instrument. Yet, OP is wondering its limitations and like to understand what kind of compounds analysts might lose to some sample heating if they switch to ED-XRFs (bench-top?). I hope this may be addressed by MaxW, when OP has said whay kind of samples they are analyzing. However, general knowledge ...

2

The unabridged Oxford English Dictionary, available by subscription, is the ultimate source to confirm the usages of English words. I checked the word "analyate" and it does not exist in the entire dictionary. The word analyte is also very recent (mid 1950s). I am not surprised that wrong spellings are published in high-end journals. If you study the ...

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To complement the previous answer: Atomic absorption lines are very sharp, with high extinction coefficient, low detection limit and are specific for the given element. Molecular absorption is band-wise, diffuse, with much lower ext. coefficient, higher detection limit and last but not least, the selectivity is lost.

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Atomic absorption spectroscopy is a quantitative measure of the elements in the analyte. We atomise the analyte so that the absorption of light corresponds to the characteristics of the elements. Otherwise how we can predict the fundamental elements when these are still part of some molecules? We measure the absorbance and refer to the Beer-Lambert law.

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The reaction of $\ce{I2}$ or $\ce{IBr}$ with double bonds is slow. You have to wait half an hour for the reaction to be finished. But of course, you may wait a longer time, maybe $\pu{3 h}$ as you suggest. Or one night. Usually we are in a hurry, and we are looking for ways of avoiding to spend too much time for a given operation. That is why the procedure ...

2

If by "fancier" you mean "uglier", then absolutely yes. Real chemistry is messy, much more than we can fully handle. The simple rate laws we learn in undergraduate physical chemistry are just approximations. I've written elsewhere that, in general, a full description of chemical kinetics for any overall reaction requires studying an entire tree of ...

2

Best practice is to try and maintain the same column length between scales. Then the scale up factor is simply the ratio of the square of the radii. If the lengths are different, try and keep the aspect ratio in the same ballpark e.g. if the length to diameter ratio is not the same but between 4 to 5 for both, you're in a better place. Then simply scale ...

1

I am afraid the measurement of the pH at half titration does not give a useful information on the pKa. There has been a detailed series of measurements of the pH at half titration for different concentrations of phosphoric acid. See Cecile Canlet, BUP 938, 1, p. 1129, November 2011. For the first H atom, the theoretical pKa should be 2.12. But the pH ...

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The mass of a particular isotope is determined by mass spectrometry. Hopefully you know this technique. In order to obtain a high degree of precision, the beam must go through several mass spectrometers coupled in series, some of which are quadrupoles or octupoles. It would take hours to explain the developments of this technique.

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OK, now with more information I can maybe help a bit more... 47-mm diameter Teflon membrane filters This seems larger than a "typical" sample. I'd guess that your commercial instrument choices would be very limited by this sample size. (Note that you'd also want to spin the samples for greater uniformity...) Typical way to analyze such a sample would be ...

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A quadrupole is a bundle of four parallel metallic bars or rods, fastened horizontally. They must be neighbors, but they must not teach one another. I will call N the highest of all (like North), S the lowest of all (like South), and E and W the two rods in the middle E at right and W at left. The whole is in a vacuum. The ions to analyze are sent in the ...

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