# Tag Info

6

Possible causes include: If it is a dispersive instrument (simultaneous recording of blank and sample in two cells): is the logic about which one is sample and blank set correctly? At least some spectrometers by PerkinElmer and Shimadzu allow to swap how front and rear path are managed by the software. How long did you run the spectrometer to warm up? ...

4

Yours is a historical question. Note that in modern chemistry, it is not required that acids have H+ or bases have OH-. The words acidity or basicity referred to certain common behaviors such as acids will liberate hydrogen when come in contact with metals, or they will decompose carbonates to carbon dioxide. Similarly, bases had other common characters. ...

3

Aqueous solutions In aqueous solution, $\ce{H+(aq)}$ and $\ce{OH-(aq)}$ are always present because of the autoionization of water: $$\ce{H2O(l) <=> H+(aq) + OH-(aq)}$$ So in aqueous solution, I would be comfortable saying there is an "association between $\ce{H+}$ and acidity, and between $\ce{OH-}$ and basicity". When the two concentration are ...

3

How would those percentages be determined in real life? Spectroscopy? You are right, this analysis comes in the domain of analytical chemistry. The fundamental requirement for formula determination is that your sample must be extremely pure. There is a whole field. So there are two broad classes of approaches. One is called classical analysis where one ...

2

This answer will change fairly frequently because technologies are always improving. These days, I think a bare minimum list might be something like: a 2.1 mm × 50 mm C18 column for rapid reversed-phase methods. a 2.1 mm × 150 mm C18 column for slower, broader-coverage reversed phase methods. a 2.1 mm × 50 mm HILIC column for rapid ...

2

The limit of detection (LOD) in these kinds of assays depends on both the noise and the signal. Usually it is defined as lowest concentration analyzed such that the signal (peak height) is three standard deviations higher than the noise. Exactly how to define "the noise" is a critical consideration -- many different sources provide different definitions ...

2

Is the spectrum due to the high voltage depends on the atomic properties of the metal? Yes, the atomic emission spectrum is unique for each element. The electrical voltage plays a secondary role in my opinion, it is rather the temperature which determines which line would be visible in the emission spectrum. These days DC arc spectroscopy is not that ...

2

This will work with the correct set up. You're constructing a galvanic cell, which will result in a cell voltage. The cell voltage will change when you alter the concentration of NaCl on either side. Important though that your two half cells (each side) are connected both electronically and ionically. Do you have a salt bridge or a membrane between them? ...

1

Zwitterionic amino acids are routinely detected by HPLC and by MS. The only challenge is to find an appropriate stationary phase. The most common stationary phases for this type of separation would include octadecyl-derivatized silica (ODS, also known as C18) and a HILIC stationary phase. Many column vendors make columns explicitly marketed for separation ...

1

Polar/hydrophilic soluble substances get dissolved, like table salt or sugar. Polar/hydrophilic insoluble substances get wet, as they attract water, like sand, or limestone. Nonpolar/hydrophobic insoluble substances do not get wet, as they repulse water, like wax, teflon or silanized glass.

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