Balancing Equations Balancing, Writing, and Naming Equations

A.word equation 1.a word equation is written out in words e.g.copper + oxygen ----> Copper oxide 2.really is not useful

B.Chemical equations 1.involves chemical symbols e.g. H 2 + O > H 2 O (not balanced) 2.much more useful C.must represent the facts H 2 + O > H 2 O not H 2 + O > H 2 O 2

D.make sure you always use the correct symbols and follow the law of conservation of mass Sodium is Na not S E. Law of conservation of mass - in a chemical reaction - mass can not be created nor destroyed -what you start with, you must also end with

F.Balancing equations 1.steps a.write down the correct symbols for the elements b.reactants go on the left - products on the right reactantsproducts the c.remember your 7 diatomics H 2, O 2, N 2, F 2, Cl 2, Br 2, I 2 is read as yields or equals

d.balance electrically (use subscripts). must do first e.balance by law of conservation of mass - use coefficients.

Balancing Equations

Reactants: 2 atoms N and 2 atoms H N 2 + H 2 NH 3 N 2 + H 2 NH 3 Nitrogen + hydrogen ammonia Nitrogen + hydrogen ammonia Products: 1 atom N and 3 atoms of H Count atoms

Balancing Equations Nothing is balanced. Nothing is balanced. Balance the nitrogen first by placing a coefficient of 2 in front of the NH 3. Balance the nitrogen first by placing a coefficient of 2 in front of the NH 3. N 2 + H 2 2NH 3 N 2 + H 2 2NH 3

Balancing Equations N 2 + 3H 2 2NH 3 N 2 + H 2 2NH 3 Place a 3 in front of H 2. Reactant side: 2 atoms N, 6 atoms H Product side: 2 atoms N, 6 atoms H Hydrogen is not balanced. Hydrogen is not balanced.

Balancing Equations Ca 3 (PO 4 ) 2 + H 2 SO 4 CaSO 4 + H 3 PO 4

Balancing Equations Side note on Ca 3 (PO 4 ) 2 Side note on Ca 3 (PO 4 ) 2 The subscript after the phosphate indicates two phosphate groups. The subscript after the phosphate indicates two phosphate groups. This means two PO 4 3- groups with two P and eight O atoms. This means two PO 4 3- groups with two P and eight O atoms.

Balancing Equations In this equation, the ion groups do not break up. In this equation, the ion groups do not break up. Instead of counting individual atoms, ion groups may be counted. Instead of counting individual atoms, ion groups may be counted. Ca 3 (PO 4 ) 2 + H 2 SO 4 CaSO 4 + H 3 PO 4

Balancing Equations Ca 3 (PO 4 ) 2 + H 2 SO 4 CaSO 4 + H 3 PO 4 Reactants: Ca 2+ – 3, PO , H + – 2, SO Products: Ca , SO , H + - 3, PO

Balancing Equations Balance the metal first by placing a coefficient of 3 in front of CaSO 4. Balance the metal first by placing a coefficient of 3 in front of CaSO 4. Products: Ca – 3 atoms, SO groups Products: Ca – 3 atoms, SO groups Ca 3 (PO 4 ) 2 + H 2 SO 4 3CaSO 4 + H 3 PO 4

Balancing Equations Three sulfate groups are needed on the reactant side so place a coefficient of 3 in front of H 2 SO 4. Three sulfate groups are needed on the reactant side so place a coefficient of 3 in front of H 2 SO 4. 3H 2 SO 4 gives 6 H + and 3 SO H 2 SO 4 gives 6 H + and 3 SO Neither phosphate nor Hydrogen is balanced. Neither phosphate nor Hydrogen is balanced. Ca 3 (PO 4 ) 2 + H 2 SO 4 3CaSO 4 + H 3 PO 4 3 A coefficient of 2 placed in front of H 3 PO 4 which balances both hydrogen and phosphate. A coefficient of 2 placed in front of H 3 PO 4 which balances both hydrogen and phosphate. 2

Balancing Equations Balancing hints: Balancing hints: Balance the metals first. Balance the metals first. Balance the ion groups next. Balance the ion groups next. Balance the other atoms. Balance the other atoms. Save the non ion group oxygen and hydrogen until the end. Save the non ion group oxygen and hydrogen until the end.

K 2 O + H 2 O ---> KOH H 2 O 2 ---> H 2 O + O 2 H 2 O 2 ---> H 2 O + O 2 Al + O 2 ---> Al 2 O 3 Al + O 2 ---> Al 2 O 3 C 7 H 16 + O 2 ---> CO 2 + H 2 O C 7 H 16 + O 2 ---> CO 2 + H 2 O Na 2 O 2 + H 2 O ---> NaOH + O 2 Na 2 O 2 + H 2 O ---> NaOH + O 2 SiO 2 + HF ---> SiF 4 + H 2 O SiO 2 + HF ---> SiF 4 + H 2 O C + H 2 O ---> CO + H 2 C + H 2 O ---> CO + H

KClO 3 ---> KCl + O 2 KClO 3 ---> KCl + O 2 H 3 AsO 4 ---> As 2 O 5 + H 2 O H 3 AsO 4 ---> As 2 O 5 + H 2 O KClO 3 ---> KClO 4 + KCl KClO 3 ---> KClO 4 + KCl Al 2 (SO 4 ) 3 + Ca(OH) 2 ---> Al(OH) 3 + CaSO 4 Al 2 (SO 4 ) 3 + Ca(OH) 2 ---> Al(OH) 3 + CaSO 4 P 4 O 10 + H 2 O ---> H 3 PO 4 P 4 O 10 + H 2 O ---> H 3 PO 4 FeCl 3 + NH 4 OH ---> Fe(OH) 3 + NH 4 Cl FeCl 3 + NH 4 OH ---> Fe(OH) 3 + NH 4 Cl

Sb + O 2 ---> Sb 4 O 6 Sb + O 2 ---> Sb 4 O 6 Ca 3 (PO 4 ) 2 + SiO 2 ---> P 4 O 10 + CaSiO 3 Ca 3 (PO 4 ) 2 + SiO 2 ---> P 4 O 10 + CaSiO 3 C 3 H 8 + O 2 ---> CO 2 + H 2 O C 3 H 8 + O 2 ---> CO 2 + H 2 O N 2 O 5 + H 2 O ---> HNO 3 N 2 O 5 + H 2 O ---> HNO 3 Fe 2 O 3 + CO ---> Fe + CO 2 Fe 2 O 3 + CO ---> Fe + CO 2 Al + HCl ---> AlCl 3 + H 2 Al + HCl ---> AlCl 3 + H

PCl 5 + H 2 O ---> HCl + H 3 PO 4 H 3 BO 3 ---> H 4 B 6 O 11 + H 2 O H 3 BO 3 ---> H 4 B 6 O 11 + H 2 O H 2 S + Cl 2 ---> S 8 + HCl H 2 S + Cl 2 ---> S 8 + HCl Mg + N 2 ==> Mg 3 N 2 Mg + N 2 ==> Mg 3 N 2 Fe + H 2 O ==> Fe 3 O 4 + H 2 Fe + H 2 O ==> Fe 3 O 4 + H 2 NaOH + Cl 2 ==> NaCl + NaClO + H 2 O Na 2 CO 3 + HCl ==> NaCl + H 2 O + CO

PHASE II PHASE II Sodium sulfate + Barium chloride  sodium chloride + barium sulfate Na SO Ba Cl +2 2 NaCl +1 + BaSO First write the equation – make sure the charges are Balanced(subscripts) Next balanced according to the Conservation of Mass (coefficients )

Copper(I) Phosphate + Barium Sulfate ---> Copper(I) sulfate + Barium Phosphate Cu 3 PO 4 + BaSO 4  Cu 2 SO 4 + Ba 3 (PO 4 ) 2 Hydrogen chloride + Iron (III) sulfate -> Iron (III) chloride + hydrogen sulfate Calcium Carbonate -----> Calcium Oxide + Carbon Dioxide Lithium Acetate + Ammonium Carbonate => Lithium Carbonate + Ammonium Acetate Calcium phosphate + Aluminum sulfate => Calcium sulfate + Aluminum phosphate

Sodium + water ==> sodium hydroxide + hydrogen copper(I) dichromate + zinc nitrate ==> copper(I) nitrate+ Zinc dichromate copper(I) dichromate + zinc nitrate ===> copper(I) nitrate+ Zinc dichromate Iron(III) sulfite + mercury(I) carbonate ===>Iron (III) carbonate + Mercury(I) sulfite

Practice Ca(OH) 2 + H 3 PO 4  H 2 O + Ca 3 (PO 4 ) 2 Ca(OH) 2 + H 3 PO 4  H 2 O + Ca 3 (PO 4 ) 2 Cr + S 8  Cr 2 S 3 Cr + S 8  Cr 2 S 3 KClO 3 (s)  Cl(g) + O 2 (g) KClO 3 (s)  Cl(g) + O 2 (g) Solid iron(III) sulfide reacts with gaseous hydrogen chloride to form solid iron(III) chloride and hydrogen sulfide gas. Solid iron(III) sulfide reacts with gaseous hydrogen chloride to form solid iron(III) chloride and hydrogen sulfide gas. Fe 2 O 3 (s) + Al(s)  Fe(s) + Al 2 O 3 (s) Fe 2 O 3 (s) + Al(s)  Fe(s) + Al 2 O 3 (s)

Types of chemical reactions Types of chemical reactions Composition – putting things together Composition – putting things together Decomposition – tearing things apart Decomposition – tearing things apart Single replacement - one element replaces Single replacement - one element replaces the other the other 2H 2 + O 2  2 H 2 O 2KClO 3  3KCl + 2 O 2 2Na Cl + F 2  2 NaF + Cl 2 Double replacement – positive and negative ions Double replacement – positive and negative ions switch place NaBr + KCl  NaCl + KBr

Meaning A balanced equation can be used to describe a reaction in molecules and atoms. A balanced equation can be used to describe a reaction in molecules and atoms. Not grams. Not grams. Chemical reactions happen molecules at a time Chemical reactions happen molecules at a time or dozens of molecules at a time or dozens of molecules at a time or moles of molecules. or moles of molecules.

Balancing Equations This method of balancing equations is the inspection method. This method of balancing equations is the inspection method. The method is trial and error. The method is trial and error. Practice. Practice.

Chemical Equations Are sentences. Are sentences. Describe what happens in a chemical reaction. Describe what happens in a chemical reaction. Reactants  Products Reactants  Products Equations should be balanced. Equations should be balanced. You should not be able to sleep knowing there are unbalanced chemical equatins You should not be able to sleep knowing there are unbalanced chemical equatins Have the same number of each kind of atoms on both sides because... Have the same number of each kind of atoms on both sides because...

Abbreviations (s)  solid (s)  solid (g)  gas (g)  gas (aq) in water (aq) in water heat heat   catalyst catalyst