Beginning of Balancing Chemical Equations

Balancing Equations What ’ s the difference between… A 2 + B 2 and A 2 B 2 ? A 2 + B 2 = Not chemically bonded, so its not a compound! These are elements. A 2 B 2 = This is chemically bonded because it is a compound.

Balancing Equations Let ’ s look at an example: Element Mg will bond with element O in the chemical reaction below: Mg + O 2 MgO Are there the same amount of O ’ s on the left as there are on the right??? NO!!! We must balance this equation!!! O MgO +  O

Balancing Equations Let ’ s look at an example: Element A will bond with element B in the chemical reaction below: A 2 + B 2 AB 2 Are there the same amount of A ’ s on the left as there are on the right??? NO!!! So, this goes against the LAW!!! We must balance this equation!!! How can we make there be the same # of each element on both sides???

Balancing Equations How can we make there be the same # of each element on both sides??? A 2 + B 2 AB 2 By putting a number in FRONT... A 2 + B 2 2AB 2 You multiply all of the elements in the compound by the number in front. Is it balanced yet??? NO!!!!

Balancing Equations Where else could we put a number to balance it? A 2 + B 2 2AB 2 We need to add a number in the front on the other side… A 2 + 2B 2 2AB 2 There are 2A ’ s and 4 B ’ s on the left AND there are 2A ’ s and 4B ’ s on the right…NOW it ’ s BALANCED!!!

**Balancing Equations How can we make there be the same # of each element on both sides??? Mg + O 2  MgO “ reactants = product ” By putting a number in FRONT... Mg + O 2  2MgO You multiply all of the elements in the compound by the number in front. Is it balanced yet??? NO! O MgO +  O

**Balancing Equations Where else could we put a number to balance it? Mg + O 2  2MgO “ reactants = product ” We need to add a number in the front on the other side… 2Mg + O 2  2MgO “ reactants = product ” There are 2Mg ’ s and 2 O ’ s on the left AND there are 2Mg ’ s and 2 O ’ s on the right…NOW it ’ s BALANCED!!!

**Balancing Equations 2Mg + O 2  2MgO I only added Coefficients! So let ’ s practice with some real problems to see how you do! Reactants =product

Balancing Equations Let ’ s practice… 1.) Al + Br 2 AlBr 3 2.) H 2 + O 2 H 2 O 3.) Na + Cl 2 NaCl 3.) 2Na + Cl 2 2NaCl 4.) Fe + O 2 Fe 2 O 3 4.) 4Fe + 3O 2 2Fe 2 O 3 5.) P 4 + O 2 P 2 O 5 5.) P 4 + 5O 2 2P 2 O 5

Balancing Equations… 1.) N 2 + H 2 NH 3 2.) Mg + O 2 MgO 3.) H 2 + Cl 2 HCl 4.) Ag + S Ag 2 S 5.) S + O 2 SO 4