Ammonium metatungstate is a weak acid, so it reacts with bases to form salts. For example, it can react with sodium hydroxide to form sodium tungstate and ammonium hydroxide:
(NH4)6[H2W12O40] + 6 NaOH → Na6[H2W12O40] + 6 NH4OH
It can also react with strong acids to form tungstic acid, which is a precursor to tungsten compounds:
(NH4)6[H2W12O40] + 12 HCl → 6 H2[W12O40] + 12 NH4Cl
