1

pH graph

Want to replicate this graph and don't know packages very well to get started drawing. Please any direction would help.

7
  • 1
    Do you have the function expressions for the curves? Jun 21 '18 at 13:49
  • No, I use to draw it with sketch app. Jun 21 '18 at 13:55
  • 1
    Ok, so you just need something similar. You might get a complete example from someone, if you want to get started yourself I'd recommend you first look at the TikZ manual, and study the tutorials in chapter 2 (and maybe 3). The examples are not exactly the same as what you want, but you can use some of the techniques described there to do most if not all of your image. Jun 21 '18 at 14:09
  • 1
    Data Visualization will set up axes and convert arbitrary units to screen coordinates. Without formulas, you will have to draw the rest one line at a time. Jun 21 '18 at 14:32
  • 2
    Not even for the axis? The first tutorial shows one way of making an axis with ticks and labels. Jun 21 '18 at 14:32
4

You can try it...

\documentclass{article}
\usepackage[margin=1cm]{geometry}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}[scale=1]
\draw[thick,->] (-1,0) --(7.5,0) node[anchor=north east] {$V_A(mL)$};
\draw[thick,->] (0,-1) --(0,7.5) node[anchor=east] {$pH$};


\draw [color=gray, dashed] (0,4.2) -- (2,4.2);
\draw [color=gray, dashed] (2,0) -- (2,4.2);
\draw [color=gray, dashed] (0,3) -- (4,3);
\draw [color=gray, dashed] (4,0) -- (4,2);
\draw [color=gray, dashed] (0,2) -- (4,2);

\draw (0,6.5) to [thick, out=0,in=90] (4,3);
\draw (0,5.3) to [thick, out=270,in=180] (2,4.2);
\draw (2,4.2) to [thick, out=0,in=90] (4,3);
\draw [thick] (4,3) -- (4,2);
\draw (4,2) to [thick, out=270,in=180] (7,0.2);

\node at (2,0) [below]{10};
\node at (4,0) [below]{20};

\node at (0,6.5) [left]{13.0};
\node at (0,5.3) [left]{11,1};
\node at (0,4.2) [left]{9,2};
\node at (0,3) [left]{7,0};
\node at (0,2) [left]{$pH_{\epsilon2}$};

\node at (-0.2,-0.3) {0};

\node at (2,4.2) {\textbullet};
\node at (4,2) [right]{$E_2$};

\end{tikzpicture}

\end{document}

enter image description here

4

Here a PSTricks solution:

\documentclass{article}
\usepackage{pstricks,pst-plot}
\begin{document}
\begin{pspicture}(0,0)(10,15)
\psaxes{->}(0,0)(0,0)(10,15)
\psplot[algebraic]{0}{10}{-14/(1+Euler^(-x+5))+14}
\rput[l](1,12){$f(x)=\frac{a}{1+\rm{e}^{-x+b}}+c$}
\end{pspicture}
\end{document}

These kind of curves also follow some mathematical functions.

Here: a=-14, b=5, c=14

enter image description here

3

You can always draw a smooth plot through a set of sample points and then use the intersections library to mark some special points.

\documentclass[tikz,border=3.14mm]{standalone}
\usetikzlibrary{intersections}
\begin{document}
\begin{tikzpicture}
\draw[latex-latex] (0,6.5) |- (9,0);
\draw[thick,name path=upper] plot[smooth] coordinates 
{(0,5.7) (2,5.4) (3,5.28) (3.5,5.2) (3.8,5) (4,4) (4.1,2) (4.3,1) (5,0.8) (8.2,0.7)};
\draw[thick,name path=lower] plot[smooth] coordinates 
{(0,4.7) (1,4.2) (2,4) (3,3.8) (3.8,3.6) (4,3.3)};
\path[name path=vert1] (2,0) -- (2,6);
\draw[name intersections={of=lower and vert1}] (2,-0.1) node[below]{10}
-- (intersection-1);
\path[name path=vert2] (4,0) -- (4,6);
\draw[name intersections={of=upper and vert2}] (4,-0.1) node[below]{20}
-- (intersection-1);
\path[name path=hori1] (0,2.2) -- (6,2.2);
\draw[name intersections={of=upper and hori1}] (-0.1,2.2)
node[left]{pH$_{\varepsilon2}$}
-- (intersection-1) node[circle,fill,scale=0.3,label=right:$E_2$]{};
\path[name path=hori2] (0,3) -- (6,3);
\draw[name intersections={of=upper and hori2}] (-0.1,3)
node[left]{$7,0$}-- (intersection-1);
\path[name path=hori3] (0,4) -- (6,4);
\draw[name intersections={of=lower and hori3}] (-0.1,4)
node[left]{$9,2$}-- (intersection-1) node[scale=0.3,fill,circle]{};
\draw (-0.1,4.7) node[left]{11,1} -- (0.1,4.7);
\draw (-0.1,5.7) node[left]{13,0} -- (0.1,5.7);
\end{tikzpicture}
\end{document}

enter image description here

2
  • 1
    does \draw (-0.1,4.7) node[left]{11,1} (0.1,4.7); should be \draw (-0.1,4.7) node[left]{11,1} -- (0.1,4.7); (and the same next code line)?
    – Zarko
    Jun 21 '18 at 18:59
  • Thanks for all effort, I am going to mess around with the code to know how it works. Jun 21 '18 at 23:00
0

If it can be useful, there is, in French, the pst-dosage package

https://melusine.eu.org/syracuse/pstricks/pc/pst-dosage/

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.