Chemical Reactions and Equations

Definition A chemical reaction is the process by which one or more substances change into one or more new substances whose chemical and physical properties differ from those of the original substances.

Writing a Chemical Reaction Reactants are the elements or compounds you begin with Products are the elements or compounds you end with Reactants Products “yield”

Numbers H+1 P-3 H2O C6H12O6 2NaCl 5H2O Superscripts show the charge of an ion Subscripts show the # of atoms in a compound Coefficients show the # of molecules H+1 P-3 H2O C6H12O6 2NaCl 5H2O

Fill in the Blanks Yields Reactants Product Subscript Coefficient

Symbols

Symbols (cont.)

Symbols (cont.)

Signs of a Chemical Change A solid precipitate is formed A gas is produced

Signs of a Chemical Change Color Change Temperature Change

Types of Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion

Synthesis A synthesis reaction starts with two or more reactants and ends up with one product.

Magnesium + Oxygen  Magnesium oxide Synthesis Magnesium + Oxygen  Magnesium oxide 2Mg + O2  2MgO

Sodium + Chlorine gas  Salt Synthesis Sodium + Chlorine gas  Salt 2Na + Cl2  2NaCl http://youtu.be/2mzDwgyk6QM

Decomposition A decomposition reaction starts with one reactant and ends up with two or more products.

Decomposition Calcium carbonate decomposes to produce calcium oxide and carbon dioxide. CaCO3  CaO + CO2

Single Replacement A single-replacement reaction starts with two reactants and ends up with two products. An element takes the place of another element that’s in a compound.

Single Replacement 2Al + 3CuCl2  3Cu + 2AlCl3 Aluminum foil is placed in a solution of copper II chloride which produces copper metal and aluminum chloride solution. 2Al + 3CuCl2  3Cu + 2AlCl3

Double Replacement A double-replacement reaction starts with two reactants and ends up with two products. In this case both reactants and products are compounds. They simply change partners.

Double Replacement 2NaCl + Pb(NO3)2  2NaNO3 + PbCl2 A solution of sodium chloride is mixed with a solution of lead nitrate resulting in the production of sodium nitrate and lead chloride. 2NaCl + Pb(NO3)2  2NaNO3 + PbCl2

Combustion A combustion reaction always involves a hydrocarbon and oxygen as reactants and ends up with carbon dioxide and water as products.

What type of reaction is this? 2H2O  2H2 + O2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 4P + 5O2  P4O10 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2MgO  2Mg + O2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? BaCl2 + H2S  BaS + 2HCl Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2Al2O3  4Al + 3O2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? Cl2 + 2NaBr  Br2 + 2NaCl Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 3H2 + N2  2NH3 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? CaCl2 + 2KBr  2KCl + CaBr2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? H2O + MgO  Mg(OH)2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2NH4CO3  2NH3 + H2O + CO2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? Cu + AgNO3  Ag + CuNO3 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2Al + 3CuCl2  3Cu + 2AlCl3 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? C + 2H2  CH4 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 3NiO + 2Li3P  3Li2O + Ni3P2 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? CuCl2 + H2S  2HCl + CuS Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2H3PO4  3H2O + P2O5 Synthesis Decomposition Single Replacement Double Replacement

What type of reaction is this? 2Na + FeO  Fe + Na2O Synthesis Decomposition Single Replacement Double Replacement