Question #60406

1 Answer
Feb 27, 2015

At room temperature, magnesium reacts very slowly with water; to speed up the reaction, magnesium is made to react with water vapor to form magnesium hydroxide and hydrogen gas by heating the sample

#2H_2O_((g)) + Mg_((s)) -> Mg(OH)_2(aq) + H_2(g)#

Here's a video of that reaction:

Chlorine reacts with water to produce a mixture of hypochlorous acid and hydrochloric acid

#Cl_(2(g)) + H_2O_((l)) -> HCl_((aq)) + HOCl_((aq))#

The hypochlorous acid will decompose when exposed to sunlight to form hydrochloric acid and oxygen gas

#2HOCl_((aq)) -> 2HCl_((aq)) + O_(2(g))#

Finally, silicon can't react with water in free form because you just can't find silicon in free form in nature. There are however a number of silicon compounds that can react with water; for example, silicon dioxide, or silica, reacts with water at high temperatures to form monosilicic acid, #Si(OH)_4# - you'll sometimes see this written as #H_4SiO_4#

#SiO_(2(s)) + 2H_2O_((l)) -> Si(OH)_(4(s))#