Equation reversal when dG is positive

[Daniel]

Hi Elad and all - enjoying the redesign. 

Noticed a new behavior that is confusing students. This is not a bug where numbers are wrong, but the equation keeps reversing direction so the sign keeps changing. 

Say you put in an equation like 

Propionate(aq) + 3 H2O(l)  ⇌ Acetate(aq) + 3 H2(aq) + CO2(total)

and the various dG's are very positive. Then, if you click on the tool to adjust abundances just a little, such as to change H2 from 1 mM to 0.1 mM

the dG's become negative. I know this can't be right, this is a very unfavorable reaction, so I look closer; the page has reversed the reaction;

Acetate(aq) + 3 H2(aq) + CO2(total)  ⇌ Propionate(aq) + 3 H2O(l)

The first few times this happened, most students didn't notice the equation reversal, as I'm normally having them investigate the impact on delta G's-- they read the negative dG without noticing the reaction change and interpret it as propionate oxidation became favorable, which is incorrect. 

If you lower hydrogen to 1 nM, the direction flips back again, because now the dG is truly favorable in the propionate oxidation direction. When working with reactions near dG of 0, one needs to be on their toes as every entry gives a negative delta G.

In my testing, if you only pull down the mM/µM/nM selector to change by orders of magnitude, the dG will instantly update, without refreshing the page. But when you type in a number or hit enter at any point, the page refreshes and the equation reverses. 

I can't imagine this is high priority, but I don't remember the earlier versions doing this - equilibrator is a great tool for teaching metabolism but a lot of my examples are low delta G values and the option to keep the reaction in the same direction would simplify its use. Thanks!

[Elad Noor]

Hi Daniel,

This is definitely an important bug to fix, thank you for letting me know about it.

I managed to locate the bug (it is indeed a bit subtle). The problem is that hitting "Enter" anywhere in the page, activates the "Reverse reaction" action (which used to be a button in the past, but now it can only be triggered by clicking the reaction arrows: ⇌).

I guess that when after you type in the new H2 concentration, you finish by hitting "Enter" (which is not necessary). If you just change the numbers the ΔG' will automatically update without reloading the page.

I'm going to disable the "Enter" action completely, so this will not happen anymore. If by tomorrow the bug is still there, please let me know.

[Daniel]

Fantastic - it now works great. Also the page is updating as fast as I change numbers in the boxes. 

I think I was hitting enter because in some cases that was needed to get the values to update (while they would update 'live' when I changed via the pull-downs). I am usually a Safari user, if that could have influenced the behavior.

Thanks for the quick fix!

Daniel