Chemical Equations A Chemical Reaction Reactants Products Yields

Chemical Equations

A Chemical Reaction Reactants Products Yields (produces)

Writing a Chemical Equation Chemical symbols give a “before-and-after” picture of a chemical reaction Reactants Mg. O + Products C magnesium oxide reacts with carbon CO to yield + Mg carbon monoxide and magnesium

Ways to represent a chemical reaction: 1. Word Equation hydrogen + oxygen water 2. Skeleton Equation H 2 + O 2 H 2 O 3. Balanced Equation 2 H 2 + O 2 2 H 2 O

Balancing Equations 1. Write the skeleton equation Make sure compound adds to zero using subscripts +2 -2 Mg + O 2 Mg. O 2. Start counting on the left and balance using coefficients ___ 2 Mg + ___ O 2 ___ 2 Mg. O 3. At arrow repeat until done You can make odd numbers even ( X 2)

Steps in Balancing An Equation Fe 3 O 4 + H 2 Fe + H 2 O Fe: Fe 3 O 4 + H 2 3 Fe + H 2 O O: Fe 3 O 4 + H 2 3 Fe + 4 H 2 O H: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O

What does it mean? 4 Al(s) + 3 O 2(g) ---> 2 Al 2 O 3(s) This equation means 4 Al atoms + 3 O 2 molecules --produces---> 2 molecules of Al 2 O 3 - AND/OR 4 moles of Al + 3 moles of O 2 --produces---> 2 moles of Al 2 O 3 -

Balancing Equations 2 Al(s) + ___ 3 Br 2(l) ---> ___ Al 2 Br 6(s) ___

Learning Check: Fe 3 O 4 + 4 H 2 3 Fe + 4 H 2 O A. Number of H atoms in 4 H 2 O 1) 2 2) 4 3) 8 B. Number of O atoms in 4 H 2 O 1) 2 2) 4 3) 8 C. Number of Fe atoms in Fe 3 O 4 1) 1 2) 3 3) 4

Practice 3 2 1. __N 2 + __H __NH 2 3 2 2. __NH 3 + __O 2 __HNO 3 + __H 2 O 3 2 3 3. __H 2 + __Fe 2 O 3 __Fe + __H 2 O 3 2 2 O 4. __C 2 H 4 + __O __CO + __H 2 2 2

Harder Practice! 2 2 2 O __Na. OH 2 1. __Na + __H 2 4 5 4 6 2. __NH + __O __NO + __H 3 2 2 O 3. Copper (II) sulfide + nitric acid copper (II) sulfate + nitrogen dioxide + water 8 8 4 __Cu. S + __HNO 3 __Cu. SO 4 + __NO 2 + __H 2 O