Buffer
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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 ] 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" create-acids starting-acid ;; creates variable amount of acid [ set color yellow ] ask acids [ ;; initializes amount of dissociated acid if random-float 100 > 98 [ dissociate ] ] if see-starting-water? [ create-waters 100 ;; creates constant volume of water [ set color blue ] ] create-conj-bases starting-conj-base ;; creates variable amount of conjugate base [ set color orange ] ask turtles ;; randomize position and heading of turtles [ setxy random-xcor random-ycor ] calculate-pH reset-ticks end ;; dissociate an acid molecule into hydronium and conj-base ;; this should only be called by turtles that are acids to dissociate ;; turtle procedure hatch-hydroniums 1 [ set color green ] set breed conj-bases set color orange end to go ask hydroxides [ react-hydroxide ] ask hydroniums [ react-hydronium ] ;; move turtles randomly around the world ask turtles [ fd 1 rt random 10 lt random 10 ] tick calculate-pH end to react-hydroxide ;; hydroxide procedure let partner one-of hydroniums-here ifelse partner != nobody [ react partner ] [ set partner one-of acids-here if partner != nobody [ react partner ] ] end to react-hydronium ;; hydronium procedure let partner one-of hydroxides-here ifelse partner != nobody [ react partner ] [ set partner one-of conj-bases-here if partner != nobody [ react partner ] ] end to react [ partner ] ;; turtle procedure ;; all hydroxide molecules will instantly react with ;; hydronium molecules and form water ifelse ([breed] of partner) = hydroniums or ([breed] of partner) = hydroxides [ set breed waters set color blue ask partner [ set breed waters set color blue ] ] [ ;; hydroxide molecules have a high probability of ;; reacting with acid molecules ifelse ([breed] of partner) = acids [ if random-float 100 > 80 [ set breed waters set color blue ask partner [ set breed conj-bases set color orange ] ] ] ;; hydronium ions will react with conjugate base to form acid [ if ([breed] of partner) = conj-bases [ if random-float 100 > 80 [ 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; instead we simply divide by ;; a factor of 1000 to bring the numbers into 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 ;; add more base to the system to add-base create-hydroxides added-base [ set color red fd 1 ] end ;; add more acid to the system to add-acid create-hydroniums added-acid [ set color green fd 1 ] end ; Copyright 2001 Uri Wilensky. ; See Info tab for full copyright and license.
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Attached files
File | Type | Description | Last updated | |
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Buffer.png | preview | Preview for 'Buffer' | over 11 years ago, by Uri Wilensky | Download |
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