Chemical Reactions

the process by which one or more substances are changed into one or more different substances Chemical Reaction

REACTANTS the starting substances in a chemical reaction (the stuff on the left)

PRODUCTS the final substances in a chemical reaction (the stuff on the right)

REPRESENTATION OF PHYSICAL STATES IN EQUATIONS (g) = gas (l) = liquid (cr) = solid (stands for crystalline) (aq) = substance dissolved in water

WRITING BALANCED EQUATIONS STEP 1: Determine the reactants and the products STEP 2: Assemble the equation STEP 3: Balance the equation (get the same # of atoms of each element on each side)

WARNING!!! Never Ever CHANGE THE SUBSCRIPT

two or more substances combine to form one new substance SYNTHESIS

A + B  AB SYNTHESIS Na + Cl 2  NaCl Pb(IV) + O 2  Pb 2 O 4

when a substance breaks up into simpler substances DECOMPOSITION

AB  A + B Decomposition NaCl  Na + Cl 2 Pb + O 2 Pb 2 O 4 

one element displaces another in a compound SINGLE DISPLACEMENT

Single Displacement Reaction

AB + C  AC + B or CB + A Single Displacement NaBr + Cl 2  NaCl + Br 2 (NH 4 ) 2 S + O 2  (NH 4 ) 2 O + S

DOUBLE DISPLACEMENT the positive or negative portions of two compounds are switched

AB + CD  AD + CB Double Displacement NaBr + Pb 2 S 3  Na 2 S + PbBr 3 K 2 SO 4 + Ba(OH) 2  KOH + BaSO 4

hydrocarbon reacts with oxygen to form carbon dioxide and water COMBUSTION (aka OXIDATION)

Writing Balanced Equations When Given Words Only STEP 1: Write out the symbols STEP 2: Balance your charges (if needed) STEP 3: Check for diatomics STEP 4: Balance Equation