Preliminaries
H−C≡C−H{\displaystyle {\ce {H-C\equiv C-H}}}
C2H2+2Ca⟶C2Ca2+H2{\displaystyle {\ce {C2H2 + 2Ca -> C2Ca2 + H2}}}
H−C≡C−H +2Ca⟶C2Ca2 + H2{\displaystyle {\ce {H-C\equiv C-H\ +2Ca->C2Ca2\ +\ H2}}}
