mhchem
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4 answers
34 votes
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Why is the letter J omitted in the spdf... sequence?
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26 votes

Omitting j when alphabetically enumerating things has a long tradition. First of all, the alphabet did not always exist in the form we know it today. Quoting Wikipedia: After [...] the 1st century ...

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2 answers
17 votes
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Arrows used in chemical reactions
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13 votes

The IUPAC Green Book (Quantities, Units and Symbols in Physical Chemistry, Third Edition, 2007) reads: 2.10.1 Other symbols and conventions in chemistry [...] (iv) Equations for chemical ...

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1 answers
27 votes
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Why did the Rio 2016 pool water turn green?
12 votes

Although not strictly alkalinity, this article quotes a changed pH level and an expert gives two possible explanations One: A low or high pH can bring out minerals. "Calcium would show itself as ...

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4 answers
8 votes
433 views
What is the simplest approach to balance a complex reaction equation?
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11 votes

$\ce{ a K4Fe(CN)6 + b Ce(NO3)4 + c KOH ->\\ d Ce(OH)3 + e Fe(OH)3 + f H2O + g K2CO3 + h KNO3}$ Because there is one $\ce{Fe}$ in $a$ and one in $e$, we know that $a=e$. To better see things, I ...

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1 answers
-4 votes
116 views
Why one gramm of O and one gramm of O2 icludes same amount of oxygen atoms?
7 votes

I think this question needs an eye-opener in non-chemical terms. Counter-question: What contains more chestnuts? a) 1 kg of "Cn" (chestnuts) b) 1 kg of "Cn2" b) 1 kg of "Cn3&...

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2 answers
6 votes
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Element Song, updated with 118 names?
7 votes

The NEW Periodic Table Song (Updated) AsapSCIENCE https://www.youtube.com/watch?v=VgVQKCcfwnU

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2 answers
6 votes
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Element Song, updated with 118 names?
5 votes

The Wikipedia page you linked to, links to the song's text which has an alternative ending containing 3 more elements. [Alternate ending:] Lawrencium and Hahnium and lastly Rutherfordium If ...

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2 answers
2 votes
182 views
How can I balance this reaction using the algebraic method?
4 votes

You are lucky. From time to time, I take on a challenge like this, just to see if I can still do it. But normally, we expect that you show some effort yourself. See our homework policy. We start off ...

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2 answers
1 votes
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Is there a difference between Ca++ and Ca(2+)?
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4 votes

They are the same. The IUPAC Green Book writes: $\ce{Al^{3+}}$ is commonly used in chemistry and recommended by [74]. The forms $\ce{Al^{+3}}$ and $\ce{S^{-2}}$, although widely used, are obsolete ...

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1 answers
-3 votes
45 views
Volume of gas in a system
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4 votes

The volume stays the same, because the containers stay the same. If the volume of one container would increase, that would mean it would expand. If in a stable container, the gas cannot take more ...

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1 answers
6 votes
88 views
Should compounds in a generic reaction be italicised (typography)?
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4 votes

Going by the basic rule of a variable (that can hold multiple values) being italic, I would go for the $r_nR_n$ style (4 times italics), but then I found the following in the IUPAC Green Book (printed ...

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1 answers
3 votes
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Editions of IUPAC Green Book
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2 votes

Wikipedia reads: The third edition of the Green Book (ISBN 978-0-85404-433-7) was first published by IUPAC in 2007. A second printing of the third edition was released in 2008; this printing made ...

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1 answers
1 votes
6k views
What does an equal sign mean in chemical equations?
2 votes

The IUPAC Green Book (Quantities, Units and Symbols in Physical Chemistry, Third Edition, 2007) reads: 2.10.1 Other symbols and conventions in chemistry [...] (iv) Equations for chemical ...

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2 answers
2 votes
192 views
A mole of atoms is the number of atoms whose total weight equals the atomic weight?
2 votes

Your textbook is inaccurate. First of all, it should be total mass, not total weight. The following statement is correct: A mole of atoms with an atomic weight of 12 has a total mass of 12 unified ...

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2 answers
1 votes
1k views
Water cooling by evaporation
2 votes

I'm pretty confuse by what the question is asking for. Because you are confused, I'll try to explain without any formulas. Please follow this step for step. Do not continue with the next step if you ...

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2 answers
3 votes
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How many atoms are represented in this equation?
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2 votes

The referenced atoms on both sides of the arrow are the exact same atoms? I like your thinking! But, chemical equations do not refer to individual atoms. The formula $\ce{Pb(NO3)2}$ can be read as "...

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