What is the point of the up arrow (↑) which shows "gas evolved" or "gas liberated", if you could just write the state symbol (g)? And would you write the up arrows (↑) and down arrows (↓) if the state symbols are already included?

  • 4
    $\begingroup$ They are pretty redundant, imo. $\endgroup$ Sep 24, 2022 at 8:10
  • $\begingroup$ Probably these arrows should've been included in Arrows used in chemical reactions. $\endgroup$
    – andselisk
    Sep 24, 2022 at 9:13
  • $\begingroup$ You can use one or the other. If you use the arrow, you don't need to write the state and vice versa. $\endgroup$ Sep 24, 2022 at 9:33
  • 1
    $\begingroup$ @NilayGhosh Arrows should not be used at all to denote states of aggregation, it's an obsolete and non-standardized notation. $\endgroup$
    – andselisk
    Sep 24, 2022 at 9:54
  • 2
    $\begingroup$ Sometimes, the up arrow is used to imply that the product is removed in the gas state, so the reaction never reaches equilibrium. If you just write (g), it might mean a closed system. However, I don't think there is consensus for interpreting it this way. For solids, you would not distinguish removing the solid from it just sitting there because continuous removal would be difficult to implement. $\endgroup$
    – Karsten
    Sep 24, 2022 at 17:49


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