Chemical Reactions Reaction Types

Chemical equation – contains all necessary info about a reaction (like a recipe). + +

The Law of Conservation of Mass: In any chemical reaction matter cannot be created or destroyed. We call this equation unbalanced because the atoms are not conserved. H 2 (g) + O 2 (g) H 2 O (g) H O HHH O 22 HH O HH O

Balancing Rules: 1.You cannot change the formula of any reactant or product. 2.You can only change the coefficients in front of the reactants and products. H2OH2O3

HCl + MgBr 2 MgCl 2 + HBr H: 1H: 1 Cl: 1 Cl: 2 Mg: 1 Br: 2 Br: 1 BALANCED 2 (2) = 2 2

K(NO 3 ) + Mg Mg(NO 3 ) 2 + K K: 1K: 1 NO 3 : 1 NO 3 : 2 Mg: 1 BALANCED 2 (2) = 2 2

Solid potassium oxide and chlorine gas react to produce potassium chloride and oxygen gas. potassium oxide chlorine potassium chloride K 2 O + Cl KCl + O (s) (g) oxygen

In nature there are millions of possible chemical reactions. Chemists have discovered that many reactions are similar. Once the chemist knows the type of reaction, then the products of the reaction can be predicted. So, the chemists have classified the reactions.

 Synthesis reactions  Decomposition reactions  Single replacement reactions  Double replacement reactions  Combustion reactions Key Words

Synthesis Reactions (Combination): 2 or more substances react to form a single substance. A + B  C S O S OO + O

Na + S Na 2 S H 2 + O 2 H 2 O K + Cl 2 KCl Fe + O 2 Fe 2 O

Decomposition Reactions: A single compound splits apart, into two or more simpler compounds. C  A + B S O S OO + O

MgCl 2 Mg + Cl 2 CO 2 CO + O 2 Al 2 S 3 Al + S

Single Replacement Reactions: One element replaces another element in a compound. More active elements replace less active elements. A + BC  AC + B A B + C

Cu + AgI Ag + CuI 2 I 2 + CuCl Cl 2 + CuI Al + ZnBr 2 Zn + AlBr 3 Ba + K(NO 3 ) K + Ba(NO 3 )

Double Replacement Reactions: 2 compounds split and exchange positive ions AB + CD  AD + CB

BaF 2 + LiBrBaBr 2 + LiF HCl + AlBr 3 HBr + AlCl 3 BeF 2 + Na 2 O BeO + NaF

Combustion Reactions: Oxygen reacts with a carbon compound to produce water, carbon dioxide and heat. C x H y + O 2  CO 2 + H 2 O

C 7 H 6 O + O 2 CO 2 + H 2 O C 3 H 8 + O 2 CO 2 + H 2 O CH 4 + O 2 CO 2 + H 2 O

Synthesis or combinationA + B  C DecompositionC  A + B Single replacementA + BC  B + AC Double replacement AC + BD  AD + BC Combustion reactions C x H y + O 2  CO 2 + H 2 O