This document describes how to generate a titration curve for a strong acid-strong base titration using Python. It involves titrating 100 mL of 2 M HCl with 1 M NaOH and plotting the pH as a function of the amount of titrant added. The Python code provided calculates the pH values at different points of titrant addition, plots the curve in three segments before, at, and after the equivalence point, and displays the final titration curve graph.

1. How to get a
titration curve by
using Python

2. Strong acid-strong base
titrations
Example
▸ Considering the titration of 100 mL
of 2 M HCl with 1 M NaOH and
plotting the pH of the solution
being analyzed as a function of the
amount of titrant added.
○ equivalence point
○ x-axis values
○ y-axis values
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3. Python example (1)
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import pylab
a1 , b1 , a2 = 2 , 0.1 , 1
c , b2 = a1*b1 , a1*b1/a2
n , eps = 50 , 1.e-10
db = b2/n
# NaOH added in mL
bs1 = pylab.linspace(db,b2,n)
bs2 = pylab.linspace(b2,2*b2,n)
# compute pH
as1 = -pylab.log10( (c - a2*bs1 + eps)/(b1 + bs2) )
as2 = 14 + pylab.log10( (a2*bs2 - c + eps)/(b1 + bs2) )

4. Python example (2)
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# plot figure
# the curve before equivalence point
pylab.plot(bs1,as1,color='r')
# the curve near equivalence point
pylab.plot([bs1[-1],bs2[1]],[as1[-1],as2[1]],color='r')
# the curve after equivalence point
pylab.plot(bs2[1:],as2[1:],color='r')
# setup figure property
pylab.title("The Titration Curve")
pylab.xlabel("Vol of NaOH added (L)")
pylab.ylabel("pH")
pylab.grid()
# display figure
pylab.show()

5. Result
The titration curve
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