# Fraction appears small on the left side of the equation and large on the right side

As you can see in the picture the fraction appears small on the left side of the equation and large on the right side.

Here's my code:

\documentclass[a4paper,12pt,parskip]{scrreprt}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{marvosym}
\usepackage{lmodern}
\usepackage{calc}
\usepackage{amsmath}
\usepackage{enumitem}
\usepackage{tabularx}
\usepackage{siunitx}
\usepackage[version=4]{mhchem}
\sisetup{locale = DE}
\usepackage[intlimits]{empheq}
\usepackage{amssymb,mathrsfs}
\usepackage{theorem}
\usepackage[pdftex]{graphicx}
\usepackage{physics}
\usepackage{nameref}
\usepackage{array}
\tolerance=2000
\setlength{\emergencystretch}{20pt} %verhindert das herrausragen von Wörtern übers Zeilenende

\begin{document}
\begin{align*}
\log v_0&=\log k_R + \alpha \cdot \log [\ce{I}]_0 \\
$\rz{I}){ }$\log 8,70\cdot 10^{-4}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log  1\cdot 10^{-5}\frac{mol}{dm^3}\\
$\rz{II}){ }$\log 3,48\cdot 10^{-3}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log 2\cdot 10^{-5}\frac{mol}{dm^3}\\
\end{align*}
\end{document}


You guys have an idea why that happens and how I can make both small? Thanks in advance!

• Welcome! How many error messages do you get when you compile this? You shouldn't use s inside the align environment. (But this is just the tip of the iceberg.) – user194703 Dec 31 '19 at 15:49 • What is the \rz command? – Bernard Dec 31 '19 at 15:53 • \rz makes Roman numbers. – Henri Lila Jan 2 '20 at 11:37 • @Schrödinger'scat, you’re right! I just removed the and all the errors (that I didn't payed attention before, since the document got so long) are gone, and the fractions are all the same size now. Thank you!! :) – Henri Lila Jan 2 '20 at 11:42

As Schrödinger's cat has pointed out, the problem lies with the  inside the align environment. \begin{align*} \log v_0&=\log k_R + \alpha \cdot \log \text{[Ar]}_0 \\ \text{I)}\log 8,70\cdot 10^{-4}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log 1\cdot 10^{-5}\frac{mol}{dm^3}\\ \text{II)}\log 3,48\cdot 10^{-3}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log 2\cdot 10^{-5}\frac{mol}{dm^3}\\ \end{align*}  Produces the desired output: Whereas \begin{align*} \log v_0&=\log k_R + \alpha \cdot \log \text{[Ar]}_0 \\\text{I)}$\log 8,70\cdot 10^{-4}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log 1\cdot 10^{-5}\frac{mol}{dm^3}\\$\text{II)}\log 3,48\cdot 10^{-3}\frac{mol}{dm^3 s} &= \log k_R + \alpha\cdot\log 2\cdot 10^{-5}\frac{mol}{dm^3}\\ \end{align*}  reproduces your problem: Note: I replaced \rz and \ce in your code with \text{...} to get your example working on my side. • mol dm etc shouldn't be set in math italic – David Carlisle Dec 31 '19 at 16:39 Since you load siunits, why not use the much simpler \SI command to typeset numbers with units. I removed the * inside align*.

\documentclass[a4paper,12pt,parskip]{scrreprt}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\usepackage{marvosym}
\usepackage{lmodern}
\usepackage{calc}
\usepackage{enumitem}
\usepackage{tabularx}
\usepackage{siunitx}
\usepackage[version=4]{mhchem}
\sisetup{locale = DE}
\usepackage[intlimits]{empheq}
\usepackage{amssymb,mathrsfs}
\usepackage{theorem}
\usepackage[pdftex]{graphicx}
\usepackage{physics}
\usepackage{nameref}
\usepackage{array}
\tolerance=2000
\setlength{\emergencystretch}{20pt} %verhindert das herrausragen von Wörtern übers Zeilenende

\begin{document}

\sisetup{per-mode=fraction}
\begin{align*}
\log v_0&=\log k_R + \alpha \cdot \log [\ce{I}]_0 \\
\mathrm{I})\;\log\SI{8.70e-4}{\mol\per\dm\cubed\per\s}&= \log k_R + \alpha\cdot \log\SI{1e-5}{\mol\per \dm\cubed\per\s}\\[1ex]
\mathrm{II})\;\log \SI{3.48 e-3}{\mol\per \dm\cubed\per\s} &= \log k_R + \alpha\cdot\log \SI{2e-5}{\mol\per \dm\cubed\per\s}
\end{align*}

\end{document}


• This loads a lot of unnecessary stuff. – user194703 Dec 31 '19 at 16:38
• @Schrödinger'scat: I didn't try to simplify the O.P.'s preamble, except for removing àmsmath since empheq is loaded. – Bernard Dec 31 '19 at 18:59
• @Bernard: Thank you! I just replaced the \$* with \mathrm{*} like you did and it works. So i don't even need the \SI` function. – Henri Lila Jan 2 '20 at 11:46