Does silicon dioxide react with alkalis?
It really does react:
\begin{align}
\ce{4HF + SiO2 &amp;-&gt; SiF4 + 2 H2O}\\
\ce{SiF4 + 2 HF &amp;-&gt; H2[SiF6]}\\
\ce{SiO2 + 2 NaOH &amp;-&gt; Na2SiO3 + H2O}\\
\ce{SiO2 + 2 F2 &amp;-&gt; SiF4 + O2}\\
\ce{SiO2 + 2 C &amp;-&gt; Si + 2 CO}\\
\ce{(2,1)Na2O + (1,1)SiO2 &amp;-&gt; Na4SiO4/Na2SiO3}\\
\ce{SiO2 + Si &amp;-&gt; 2 SiO}
\end{align}