增加方程之间的间距

Question

\documentclass[11pt]{article}  
\usepackage{siunitx}
\usepackage{amsmath}

\begin{document}
\begin{align*}
\text{Concentration of unknown sample solution} &= \frac{303 - 0.00227}{0.215} \\
&= 1.400 \si{\mg \per \L}
\end{align*}
\end{document}  

有可能出现这样的换行吗？

concentration of unknown =
    sample solution

并增加方程式之间的间距？

Answer 1

\documentclass[11pt]{article}  
\usepackage{siunitx}
\usepackage{amsmath}

\begin{document}
\begin{align*}
\parbox{5cm}{\centering Concentration of unknown sample solution} 
&= \frac{303 - 0.00227}{0.215} \\[\jot]
&= \SI{1.400}{\mg \per \L}
\end{align*}
\end{document}