I recently came across this chemical equation :

$$\ce{2HNO3 + Na2Co3 -> 2NaNO3 + CO2 + H2O}$$

The equation describes the reaction between Nitric Acid and Sodium Carbonate, the equation states that the resulting compounds $\ce{2NaNO3}$ carbon dioxide and water would be created. However my question is how the formula should be written out. I have always written a chemical equation like this :

$$\ce{(HNO3)2 + Na2Co3 -> (NaNO3)2 + CO2 + H2O}$$

Do both ways of writing the equation state the same thing? If so which one should I use. Which form of writing the equation is considered "more correct", used more commonly or considered "more standardized".

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    $\begingroup$ You have always written it wrong. $\endgroup$ – Ivan Neretin Jan 26 '18 at 12:02
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    $\begingroup$ Not to mention that Co3 is tricobalt, whereas CO3 is carbonate. Mind capitalization too, it's very important. Voting to close as homework (seriously, read any introductory book on chemistry). $\endgroup$ – andselisk Jan 26 '18 at 12:05
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    $\begingroup$ @andselisk 'A "homework question" is any question whose value lies in helping you understand the method by which the question can be solved, rather than getting the answer itself.' Imho this doesn't apply here. $\endgroup$ – GreenSmurf Jan 26 '18 at 21:48
  • $\begingroup$ This question is about a fundamental misunderstanding of how the rules work. Perhaps the OP should have done a little research first, and this question is essentially too simple, but to shut it down this way doesn't seem to fit. To take a whole species and add parents and subscript kinda says it is 2 or 3 of them..... $\endgroup$ – MarsJarsGuitars-n-Chars Apr 13 '18 at 16:14

According to the IUPAC guidelines arabic numerals are used:

(a) As right subscripts, to indicate the number of individual constituents (atoms or groups of atoms)

(c) To indicate the composition of (formal) addition compounds or non-stoichiometric compounds. The numeral is written on the line before the formula of each constituent.

Source: IUPAC recommendations found here

This essentially means that the first variant is correct.

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    $\begingroup$ @andselisk Point taken. Is it better now? $\endgroup$ – GreenSmurf Jan 26 '18 at 21:46
  • $\begingroup$ Thank you, that's much better IMO, -1 -> +1 :) $\endgroup$ – andselisk Jan 26 '18 at 22:14

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