balancing equations

• is (__CaO + __H₂O → __Ca(OH)₂) balanced?

  yes
• __Na + __F₂ → __NaF?

  2,1,2
• is (__Na + __MgF₂ → __NaF + __Mg) balanced?

  no - 2,1,2,1
• __BaCl₂ + __Na₂SO₄ → __NaCl + __BaSO₄?

  1,1,2,1
• is (__Sn + __HF → __SnF₂ + __H₂) balanced?

  1,2,1,1
• A chemical substance that is present at the start of a chemical reaction?

  reactant
• A chemical substance formed as a result of a chemical reaction?

  product