# Tag Info

16

When looking at IR spectra of hydrogen-bonding groups, always check how IR spectra was recorded. It appears that NIST spectra is recorded using gas phase, while the first one used liquid film. In liquid film $\ce{NH2}$ groups form a network of hydrogen bonds, resulting in shape distortion and widening of $\ce{NH2}$-related bands. Same is true for carboxylic ...

14

Avoiding cooling again after keeping it ( for non critical products ) at room temperature is mainly to prevent forgetting it was not cold all the time and that it may will not last as long as expected. Taking food from the fridge, you may not remember after a week or two that it was outside longer than it should be. It can violate the safety by growth of ...

10

Answer here from a quality manager in the pharmaceutical field in Europe. Pharmaceutical companies are obliged to perform stability tests for their products according to the relevant pharmaceutical (GMP) agency in your market (FDA/EMA/etc) and the international agreed guidelines like ICH Q1A-F and the WHO). These tests are carried out in stability chambers ...

6

Honestly I have doubt about your textbook version of IR spectrum. However, I can suggest by the experience I have gained that the shapes of the peaks depends on the method you have used to obtain the spectra such as ATR, smear, absorbed in inert surface, etc., thus cannot pinpoint which one is incorrect. Yet, you can compare an one with other related amines. ...

5

The single measured values provided by 3 different tools gives us just a hint about possible accuracy or precision of the tools. The tool providing the value 1.39 is probably, but not necessarily more precise and accurate than the other two. What these values really say is just the tool resolution. There are 4 terms: resolution precision accuracy(1), also ...

3

In order for a combustible substance to ignite, it must first attain a certain temperature called the 'autoignition point', which is the minimum temperature that the substance requires to begin combustion. In this case, the banknote didn't 'burn' because the water present absorbs the majority of the energy given off by the combustion of ethanol, which keeps ...

3

It's easy to find a slew of test papers and strips online. For example, a quick search of Amazon for "test papers" turned up chlorine test strips for pools and sanitation, glucose test strips for diabetes, phenylthiourea genetic-linked taste tests, UV-C dose test cards, lead acetate paper test for $\ce{H2S}$, WBC and nitrite test strips for UTI... ...

3

UPDATE: Today I got a chance to read the abstract the original paper which made news everywhere that moon has rust on the side which faces the Earth. The authors propose that upper atmosphere oxygen from the Earth reaches the moon. In their words "Oxygen delivered from Earth’s upper atmosphere could be the major oxidant that forms lunar hematite. ...

2

Spectator ions in any kind of reaction are those that do not take part in the interaction. In precipitation reactions, they are those not forming the least soluble salt. In acid-base reactions, they are those not manifesting in the given environment either acidic, either basic behaviours. Typically cations of alkali metal, or alkali earth metals, or anions ...

2

Yes, “propanol 1-2 diol 178” is the same compound as propylene glycol and appears to be a fabricated name used in a manual for a proprietary cleaning system by Kirmuss Audio. According to the article from Analog Corner magazine [1, p. 22] (emphasis on the footnote): The Kirmuss Audio KA-RC-1 comes with accessories: 60 mL of an antibacterial/antistatic/...

2

The capacity of a cell is measured toward the terminal cut off voltage. If e.g.a double current is drained from a cell, the external cell voltage is decrease by the doubled voltage drop on the cell internal resistance: $$U_\mathrm{e}=U_0 - R \cdot I$$ That caused reaching the terminal voltage sooner then in the half time. It is additionally leading to the ...

2

Many compounds are added to dangerous substances that might be accidentally or deliberately ingested There isn't just one, universal, answer to this question. The problem is that there are a variety of different hazards and specific countermeasures may be required for each. And ingestion of some dangerous materials occurs deliberately not just accidentally ...

2

It is denatonium benzoate. This comes from wikipedia page of denatonium: Denatonium, usually available as denatonium benzoate (under trade names such as Denatrol, BITTERANT-b, BITTER+PLUS, Bitrex or Aversion) and as denatonium saccharide (BITTERANT-s), is the most bitter chemical compound known, with bitterness thresholds of 0.05 ppm for the benzoate and 0....

2

Following a discussion that took place in the comments: If given answers are correct, as Poutnik pointed out, your equation should be : $$\require{cancel}\ce{A(g) + B(g)<=>2 C(g)}$$ - Mathew Mahindratne Could you explain how you arrived at that conclusion? - Ollie This answer solves this question for a general case: \ce{a A(g) + b B(g) <=> c ...

2

When you talk about the ionization energy of $\ce{Mg^2+}$, it is the third ionization of $\ce{Mg}$, which is equal to $\pu{7734 kJ/mol}$. When you talk about the ionization energy of $\ce{Ne}$, it is the first ionization of $\ce{Ne}$, which is $\pu{2081 kJ/mol}$. Thus, actually, $IE_\ce{Mg^2+} \gt IE_\ce{Ne}$. Keep in mind that the first and second ...

2

You'll get an answer quickly if you search for "formulation liquid soap". There are for instance DIY guides on making liquid soap starting from natural oils (sunflower, coconut) by saponifying the oil with KOH. The fatty acid composition of sunflower oil can vary significantly depending on breed (see e.g. the Wikipedia) but generally contains mono- ...

2

The deviation can be in range from negligible to huge, depending on the level of nonhomogeneity and locality of the sample. Note that routine analysis of potentially non-homogenous sources involve sophisticated sampling and sample averaging schema, so the result is representing number.

1

Azeotropic distillation. Example from this patent: here Acetic acid is difficult to separate from water by conventional distillation or rectification because of the close proximity of their boiling points. Acetic acid can be readily separated from water by using azeotropic distillation. Typical examples of effective agents are ethyl n-valerate and 4-methyl-...

1

Interesting that the cost in the US for the USDA-approved form is US$900 per 1.5 ml IV ampule. (Specific gravity is given as ~1, i.e. 1.5 g per ampule). That chemical, 4-methylpyrazole, "For Research Use Only. Not Intended for Diagnostic or Therapeutic Use.", is available for US$74 per g . So if standard use is 1.5 ml, then the research-grade ...

1

Sulfur dioxide is not a problem ; in an aquarium it will make very dilute sulfurous acid which will likely neutralize with some carbonate mineral/gravel. H2S is lethal , extended exposure at 50 ppm for a day , or short exposure at 500 ppm. On the other hand , what you smell in aquarium sand is less then 1 ppm, the sense of smell is very sensitive to H2S. ...

1

What is rust? According to Wikipedia, rust is an iron oxide, a usually reddish brown oxide formed by the reaction of iron and oxygen in the presence of water or air moisture. So, how does rust is forming on Moon although it has no Earth-like atmosphere, devoid of oxygen/moisture? According to nasa.gov: moon has trace amounts of oxygen. The source of that ...

1

The picture of the product (2-4 mm granules) on the website looks very homogeneous. If you consider the product acceptable, except for possible inhomogeneity, you could examine smaller samples or homogenize larger portions. Dissolving in water seems the easiest way, and could provide a further check on purity/homogeneity. $K_2SO_4$ is soluble in water about ...

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