set all words in color for a part of a table

Question

To write the solution of an exercise, i want to fill in the tabular with the answers in red. The headlines of the table should stay in the same style than the exercise and only a part of the table should be colorized. I can achieve that by using \textcolor{red}{...} in each cell of my table but it's pretty brutal. I'm looking for a solution to declare that all the following words must be in red untill the end of the environment tabular.

I've tried some \color{red} but it doesn't work.

Here is a small example.

\documentclass[11pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}

\usepackage{colortbl}
\usepackage{chemformula}
\begin{document}
    \begin{center}
        \footnotesize
        \renewcommand{\arraystretch}{1.5}
        \hspace*{-1cm}\begin{tabular}{|c|c|c||c|c|c|c|c|c|c|c|}
            \hline \rowcolor{black}
            \multicolumn{11}{|c|}{\textcolor{white}{Corps purs}}\\\hline
            \rowcolor{gray!90}
            élémentaires&
            \multicolumn{2}{c||}{simples} &  \multicolumn{8}{c|}{composés}\\ 
            \hline
            \rowcolor{gray!70}
            &métal.& non-métal. & \multicolumn{2}{c|}{Oxydes} & Hydroxydes & \multicolumn{2}{c|}{Acides}  & \multicolumn{2}{c|}{Sels}  & Corps organiques\\ 
            \hline 
            \rowcolor{gray!50}
            &&  & métal. & non-métal. &  & bin. & tern. & bin. & tern. &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\ch{C6H12O6}\\ 
            \hline 
            && \ch{Fe2O3} &  &  &  &  &  &  &  &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\
            \hline 
        \end{tabular}
    \end{center}
\end{document}

Desired output :

PS : i'm aware that Fe2O3 is at the wrong place, it was only for a second element :) !

Answer 1

Assuming that every entry in your table also uses \ch, you can define your own command as follows:

\documentclass[11pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}

\usepackage{colortbl}
\usepackage{chemformula}

\newcommand{\redch}[1]{\textcolor{red}{\ch{#1}}}
\begin{document}
    \begin{center}
        \footnotesize
        \renewcommand{\arraystretch}{1.5}
        \hspace*{-1cm}\begin{tabular}{|c|c|c||c|c|c|c|c|c|c|c|}
            \hline \rowcolor{black}
            \multicolumn{11}{|c|}{\textcolor{white}{Corps purs}}\\\hline
            \rowcolor{gray!90}
            élémentaires&
            \multicolumn{2}{c||}{simples} &  \multicolumn{8}{c|}{composés}\\ 
            \hline
            \rowcolor{gray!70}
            &métal.& non-métal. & \multicolumn{2}{c|}{Oxydes} & Hydroxydes & \multicolumn{2}{c|}{Acides}  & \multicolumn{2}{c|}{Sels}  & Corps organiques\\ 
            \hline 
            \rowcolor{gray!50}
            &&  & métal. & non-métal. &  & bin. & tern. & bin. & tern. &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\redch{C6H12O6}\\ 
            \hline 
            && \redch{Fe2O3} &  &  &  &  &  &  &  &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\
            \hline 
        \end{tabular}
    \end{center}
\end{document}

You could also use \setchemformula{format=\color{red}} inside of the center environment to change the color of a \ch inside of that environment:

\documentclass[11pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}

\usepackage{colortbl}
\usepackage{chemformula}


\begin{document}
    \begin{center}
    \setchemformula{format=\color{red}}
        \footnotesize
        \renewcommand{\arraystretch}{1.5}
        \hspace*{-1cm}\begin{tabular}{|c|c|c||c|c|c|c|c|c|c|c|}
            \hline \rowcolor{black}
            \multicolumn{11}{|c|}{\textcolor{white}{Corps purs}}\\\hline
            \rowcolor{gray!90}
            élémentaires&
            \multicolumn{2}{c||}{simples} &  \multicolumn{8}{c|}{composés}\\ 
            \hline
            \rowcolor{gray!70}
            &métal.& non-métal. & \multicolumn{2}{c|}{Oxydes} & Hydroxydes & \multicolumn{2}{c|}{Acides}  & \multicolumn{2}{c|}{Sels}  & Corps organiques\\ 
            \hline 
            \rowcolor{gray!50}
            &&  & métal. & non-métal. &  & bin. & tern. & bin. & tern. &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\ch{C6H12O6}\\ 
            \hline 
            && \ch{Fe2O3} &  &  &  &  &  &  &  &\\ 
            \hline 
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\ 
            \hline
            &&  &  &  &  &  &  &  &  &\\
            \hline 
        \end{tabular}
    \end{center}
\end{document}

Answer 2

A possible solution (if I understand your question correct) is to direct a \color{red} command into all columns. I have defined a new column type R for the purpose. Thereafter, you enclose the heading text in \multicolumn{1}{c|}{<text>} to protect against colourisation.

You may adapt David Carlisle answer to this question to your code, and define a new column that accepts a \rowfont-command (also defined in the code):

Example 1 – defining a \rowfont-command

\documentclass[11pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage{array}

\newcolumntype{C}{>{\rowfont}c}
\newcommand\setrowfont[1]{\noalign{\gdef\rowfont{#1}}}
\gdef\rowfont{}

\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}

\usepackage{colortbl}
\usepackage{chemformula}
\begin{document}
    \begin{center}
        \footnotesize
        \renewcommand{\arraystretch}{1.5}
        \hspace*{-1cm}\begin{tabular}{|*{3}{C|}|*{8}{C|}}
            \hline \rowcolor{black}
            \multicolumn{11}{|c|}{\textcolor{white}{Corps purs}}\\\hline
            \rowcolor{gray!90}
            élémentaires &
            \multicolumn{2}{c||}{simples} &
            \multicolumn{8}{c|}{composés}\\ 
            \hline
            \rowcolor{gray!70}
            &
            métal. &
            non-métal. &
            \multicolumn{2}{c|}{Oxydes} &
            Hydroxydes &
            \multicolumn{2}{c|}{Acides} &
            \multicolumn{2}{c|}{Sels} &
            Corps organiques\\ 
            \hline 
            \rowcolor{gray!50}
            &&  &
            métal. &
            non-métal. &
            &
            bin. &
            tern. &
            bin. &
            tern. &\\ 
            \hline \setrowfont{\color{red}}
            &&  X&  &  &  &  &  &  &  &\ch{C6H12O6}\\ 
            \hline 
            && \ch{Fe2O3} &  &  &  &  &  &  &  &\\ 
            \hline 
            X&X& X & X & X & X & X & X & X & X &X\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\
            \hline 
        \end{tabular}
    \end{center}
\end{document}

Example 2 – >{color{red} and\multicolomn}}

\documentclass[11pt,a4paper]{report}
\usepackage[utf8]{inputenc}
\usepackage{array}

\usepackage[left=1.00cm, right=1.00cm, top=1.00cm, bottom=1.00cm]{geometry}

\newcolumntype{R}{>{\color{red}}c}

\usepackage{colortbl}
\usepackage{chemformula}
\begin{document}
    \begin{center}
        \footnotesize
        \renewcommand{\arraystretch}{1.5}
        \hspace*{-1cm}\begin{tabular}{|*{3}{R|}|*{8}{R|}}
            \hline \rowcolor{black}
            \multicolumn{11}{|c|}{\textcolor{white}{Corps purs}}\\\hline
            \rowcolor{gray!90}
            \multicolumn{1}{c|}{élémentaires} &
            \multicolumn{2}{c||}{simples} &
            \multicolumn{8}{c|}{composés}\\ 
            \hline
            \rowcolor{gray!70}
            &
            \multicolumn{1}{c|}{métal.} &
            \multicolumn{1}{c||}{non-métal.} &
            \multicolumn{2}{c|}{Oxydes} &
            \multicolumn{1}{c|}{Hydroxydes} &
            \multicolumn{2}{c|}{Acides}  &
            \multicolumn{2}{c|}{Sels} &
            \multicolumn{1}{c|}{Corps organiques}\\ 
            \hline 
            \rowcolor{gray!50}
            &&  &
            \multicolumn{1}{c|}{métal.} &
            \multicolumn{1}{c|}{non-métal.} &
            &
            \multicolumn{1}{c|}{bin.} &
            \multicolumn{1}{c|}{tern.} &
            \multicolumn{1}{c|}{bin.} &
            \multicolumn{1}{c|}{tern.} &\\ 
            \hline 
            &&  X&  &  &  &  &  &  &  &\ch{C6H12O6}\\ 
            \hline 
            && \ch{Fe2O3} &  &  &  &  &  &  &  &\\ 
            \hline 
            X&X& X & X & X & X & X & X & X & X &X\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\ 
            \hline
            &&  X&  &  &  &  &  &  &  &\\
            \hline 
        \end{tabular}
    \end{center}
\end{document}