White growth on unopened bottle of chlorotrimethylsilane
Chlorotrimethylsilane, like other organosilicon compounds, is easily attacked by nucleophiles and readily hydrolyzes in air yielding hydrogen chloride:
$$\ce{2 Me3SiCl(l) + H2O(l) -&gt; Me3Si-O-SiMe3(l) + 2 HCl(g)}$$
Hydrogen chloride reacting with traces of ammonia $\ce{NH3}$ in the air builds up white solid ammonium chloride $\ce{NH4Cl}$ depositing on the nearby surfaces.
Also, the final product of hydrolysis for the majority of organosilicon compounds is silicon dioxide $\ce{SiO2}$ (sol-gel process similar to olation). Fine powder of silicon dioxide is white as well.