User request: add Sodium Chloride as solute

[oliver-phet]

I was wondering is there any way to put Sodium Chloride (NaCl) as a compound in the concentration simulation Phet has. I am trying to build a desalination unit in WISE and I wanted to embed the Phet concentration simulation. It would be fantastic if one of the compounds was NaCl so that students could consider saltwater concentrations. Thank you.

Assigning to @ariel-phet

[ariel-phet]

@amyh-phet what do you think? Salt seems like the quintessential solute...think there is a reason we did not put it in? I am guessing part of the reason for not using salt was the color of the liquid will not change much to give a visual cue of concentration.

@pixelzoom my impression is the model is written in such a way that adding another solute to the concentration screen would not be difficult (although might be tricky on the BL screen without the spectroscopic data)?

[amyh-phet]

@ariel-phet and @pixelzoom While NaCl is a commonly discussed solute, I think that the clear, colorless solution that would result does not allow the user to connect solution color to concentration. Mathematically I see no difficulty with adding NaCl to the sim, but it would not be useful in the BL screen.

[pixelzoom]

The "Concentration" and "Beer's Law" screens use different models. While the lists of solutes/solutions are currently the same, it is possible to add a new solute to ConcentrationModel without adding a corresponding solution to BeersLawModel. So we could conceivably add NaCl to the "Concentration" screen only.

Impact: (1) NaCl solution will show no change in color as concentration changes, as noted above by @amyh-phet. (2) Different combo box lists between Concentration and Beer's Law screen (NaCl absent in latter).

If you want to move forward with adding NaCl, we'll need the following properties:

• common name (Salt? Table Salt?) • formula (NaCl) • stock concentration, in mol/L • molar mass, in g/mol • 3 colors (min, middle, max) used to denote solution concentration (all fully transparent?) • color for precipitate particles (fully transparent?)

[amyh-phet]

@pixelzoom I can get the needed information to you tomorrow. I'd like to dig a bit to see if we need to model the solution as fully transparent across all concentrations used in the sim.

[pixelzoom]

@ariel-phet Priority? Maintenance release or minor version increment? A maintenance release will have higher development cost, but require less testing. A minor release will have lower development cost, but requires a full RC test cycle, and requires triaging open issues to see what other changes will be picked up.

[ariel-phet]

Definitely a minor release.

Priority is "as time allows" - Function Builder is definitely the priority, but if you need something that is a bit less mentally taxing feel free to tackle the enhancement.

[amyh-phet]

@pixelzoom

• Common name: Table salt
• formula: NaCl
• stock concentration: 5.50 mol/L
• molar mass: 58.443 g/mol
• solubility: 6.15 mol/L
• 3 colors:

min: no color-fully transparent middle: no color-fully transparent max: Would be nice to add a bit of opacity here. Can we try f1f2f2 at 40% transparency?

• color for precipitate particles: f1f2f2 (very light gray)

Let me know if you need more info from me or if colors for solution/precipitate needs

[pixelzoom]

Reminder to self: add corresponding entry to beers-law-lab-api.js.

[pixelzoom]

Moving this issue to https://github.com/phetsims/beers-law-lab/issues/169, since this work will be done in the beers-law-lab repository.