Chemical Equation & Reaction Notes-Chemical reactions – occur when chemical bonds (ionic, covalent) between atoms are broken and new bonds are formed

-Chemical equation – used to describe chemical reactions through symbols & numbers

Example of chemical equation:aluminum sulfate plus barium chloride yields

aluminum chloride plus barium sulfate

Al2(SO4)3 + 3 BaCl2 2 AlCl3 + 3 BaSO4

• Label the following: – Reactants - Products -Coefficients - Subscripts - Produces or yields

Terms or symbols used in equations• “+” or “and” - used as divider between

reactants or products• → yields, reacts, produces, forms, …• reversible reaction• CATALYST is something that speeds up the reaction,

but it is not used as a chemical part of the reaction; written on top of the yield sign

• Heat or ∆ or MnO2 or elec

More terms and symbols

• (s) solid• (l) liquid• (aq) aqueous, dissolved in water• (g) gas• NR no reaction

•There are 5 types of chemical reactions

#1 - Synthesis• Reactants combine to form 1 compound (aka, combination rxn) reactant + reactant product• Basically: A + B AB

• Ex : 2 H2 + O2 2 H2O

• Ex: C + O2 CO2

Synthesis Reaction (continued)• Here is another example of a synthesis rxn:

#2 - Decomposition• occur when a compound breaks up into 2 or

more products (can be elements or compounds)• 1 Reactant Product + Product • In general: AB A + B• Ex: 2 H2O 2 H2 + O2

• Ex: 2 HgO 2 Hg + O2

Decomposition (continued)• Another view of a decomposition reaction:

#3 - Single Replacement• occur when one element replaces another in a

compound (aka, single displacement)• AB + C CB + A• Metals must be more reactive in order to replace

another metal (called the Activity Series)• Zn(s) + HCl(aq) ZnCl2 + H2(g)

#4 – Double Replacement• Occurs when 2 ionic compounds “switch partners”

and produce 2 different compounds• Compound + compound compound+ compound• AB + CD AD + CB• Ex: AgNO3(aq) + NaCl(s) AgCl(s) + NaNO3(aq)

#5 - Combustion• occur when a hydrocarbon reacts with oxygen• This is also called burning• In general:

CxHy + O2 CO2 + H2O• Products in combustion are ALWAYS carbon

dioxide and water. (incomplete combustion will also produce carbon monoxide)