$(1) Cr + 2HCl \to CrCl_2 + H_2$
$(2) CrCl_2 + 2KOH \to Cr(OH)_2 + 2KCl$
$(3) 4Cr(OH)_2 + O_2 + 2H_2O \to 4Cr(OH)_3$
$(4) Cr(OH)_3 + NaOH \to Na[Cr(OH)_4]$
$(5) 2CrCl_2 + Cl_2 \to 2CrCl_3$
$(6) Cr(OH)_3 + 3HCl \to CrCl_3 + 3H_2O$
\(1,Cr+2HCl\rightarrow CrCl_2+H_2\uparrow\)
\(2,CrCl_2+2NaOH\xrightarrow[]{t^0}\)\(Cr\left(OH\right)_2\downarrow+2NaCl\)
\(3,4Cr\left(OH\right)_2+O_2+2H_2O\rightarrow4Cr\left(OH\right)_3\)
\(4,Cr\left(OH\right)_3+NaOH\rightarrow Na\left[Cr\left(OH\right)_4\right]\)
\(5,2CrCl_2+Cl_2\xrightarrow[]{t^0}2CrCl_3\)
\(6,Cr\left(OH\right)_3+3HCl\rightarrow CrCl_3+3H_2O\)
