Weak Acid

Weak Acid preview image

2 collaborators

Uri_dolphin3 Uri Wilensky (Author)
Mike Stieff (Author)

Tags

chemical reactions 

Tagged by Reuven M. Lerner about 9 years ago

chemistry and physics 

Tagged by Reuven M. Lerner about 9 years ago

Model group CCL | Visible to everyone | Changeable by group members (CCL)
Model was written in NetLogo 5.0.4 • Viewed 221 times • Downloaded 33 times • Run 1 time
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breed [waters water]            ;; water molecules
breed [hydroniums hydronium]    ;; hydronium ions (green)
breed [hydroxides hydroxide]    ;; base molecules (red)
breed [acids acid]              ;; parent acid molecules (yellow)
breed [conj-bases conj-base]    ;; conjugate base molecules of parent acid (orange)


globals [
  pH
  Ka             ;; variable for acid reactions
  base-added     ;; use to keep track of how much total base has been added
]

to setup
  clear-all
  set-default-shape waters "molecule2"
  set-default-shape hydroniums "molecule3"
  set-default-shape hydroxides "molecule1"
  set-default-shape acids "molecule2"
  set-default-shape conj-bases "molecule1"
  set Ka 1.9
  create-acids vol-acid                 ;; adds parent acid molecules
    [ set color yellow ]
  ask acids
    [ if random-float 100.0 < Ka              ;; creates initial dissociated acid
        [ hatch-hydroniums 1
            [ set color green
              fd 3 ]
         set breed conj-bases                 ;; parent turtle turns into a conj-base
         set color orange ] ]
  create-waters (100 - count hydroniums)
    [ set color blue ]
  ask turtles                   ;; randomize position and heading of turtles
    [ setxy random-xcor random-ycor ]
  set base-added 0
  calculate-pH
  reset-ticks
  plot-pH
end 

to go
  ask hydroxides [ react-hydroxide-hydronium ]
  ask hydroxides [ react-hydroxide-acid ]
  ask acids [ react-acid ]
  ask hydroniums [ react-hydronium ]
  ;; move turtles randomly around the world
  ask turtles
    [ fd 1
      rt random 10
      lt random 10 ]
  tick
  calculate-pH
  plot-pH
end 

;; adds base molecules to the solution

to add-base
  create-hydroxides vol-base
    [ fd 1
      set color red ]
  set base-added base-added + vol-base
end 

;; hydroxide procedure

to react-hydroxide-hydronium
  let partner one-of hydroniums-here     ;; tells hydroxide to recognize hydronium
  if partner != nobody              ;; if you are a hydroxide molecule and you encounter a hydronium
    [ ;; then turn yourself and the hydronium into water molecules
      set breed waters
      set color blue
      ask partner
        [ set breed waters
          set color blue ] ]
end 

;; hydroxide procedure

to react-hydroxide-acid
  if random-float 100.0 < Ka                  ;; react with acid molecules according to the acid strength
    [ let partner one-of acids-here
      if partner != nobody              ;; if you are a hydroxide molecule and you encounter an acid molecule
        ;; then turn the hydroxide into a conjugate base molecule
        ;; and turn yourself into a water molecule
        [ set breed waters
          set color blue
          ask partner
            [ set breed conj-bases
              set color orange ] ] ]
end 

;; acid procedure

to react-acid
  if random-float 100.0 < Ka                  ;; acid molecules may dissociate to hydronium depending on their Ka
    [ let partner one-of waters-here
      if partner != nobody              ;; if you are an acid molecule and you encounter a water molecule
        ;; then turn the water molecule into a hydronium molecule
        ;; and turn yourself into a conjugate base molecule
        [ set breed conj-bases
          set color orange
          ask partner
            [ set breed hydroniums
              set color green ] ] ]
end 

;; hydronium procedure

to react-hydronium
  if random-float 100.0 < Ka                  ;; hydronium molecules may recombine with conjugate base to form acid
    [ let partner one-of conj-bases-here
      if partner != nobody              ;; if you are a hydronium molecule and you encounter a conjugate base molecule
      ;; then turn the conjugate base molecule into an acid molecule
      ;; and turn yourself into a water molecule
        [ set breed waters
          set color blue
          ask partner
            [ set breed acids
              set color yellow ] ] ]
end 

;; calculates the pH from the amount of the various ions in solution;
;; note that for simplicity the calculations don't take the true molar
;; concentration of water into account, but instead use an arbitrarily
;; chosen factor of 1000 to produce numbers lying in a reasonable range

to calculate-pH
  let volume count turtles
  let concH (count hydroniums / volume)
  let concOH (count hydroxides / volume)
  ifelse (concH = concOH)
    [ set pH 7 ]
    [ ifelse (concH > concOH)
      [ set pH (- log (concH / 1000) 10) ]
      [ let pOH (- log (concOH / 1000) 10)
        set pH 14 - pOH ] ]
end 

;; plotting procedures

to plot-pH
  set-current-plot "pH Curve"
  plot pH
end 

to record-pH
  set-current-plot "Titration Curve"
  plotxy base-added pH
end 


; Copyright 2001 Uri Wilensky.
; See Info tab for full copyright and license.

There are 10 versions of this model.

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Uri Wilensky over 9 years ago Updated to NetLogo 5.0.4 Download this version
Uri Wilensky almost 10 years ago Updated version tag Download this version
Uri Wilensky almost 10 years ago Updated to version from NetLogo 5.0.3 distribution Download this version
Uri Wilensky over 10 years ago Updated to NetLogo 5.0 Download this version
Uri Wilensky over 12 years ago Updated from NetLogo 4.1 Download this version
Uri Wilensky over 12 years ago Updated from NetLogo 4.1 Download this version
Uri Wilensky over 12 years ago Updated from NetLogo 4.1 Download this version
Uri Wilensky over 12 years ago Updated from NetLogo 4.1 Download this version
Uri Wilensky over 12 years ago Model from NetLogo distribution Download this version
Uri Wilensky over 12 years ago Weak Acid Download this version

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