Chapter 11
Balancing
Reaction
Each side of the equation has the same amount of atoms of each element and mass is conserved
Example
Unblanced: H2O2 —> H20 + O2
Balanced: 2H202 —> 2H2O + O2
Word Equations
Reactants are on the left and products are on the right. An arrow separates them, arrows mean yields, gives, reacts, to produce
Examples
Iron + oxygen —> Iron(iii) oxide
Examples:
Sodium phosphate and calcium chloride react to form calcium phosphate and sodium chloride.
Reaction Types
Combination
2 or more substances react to form a single substance
Examples
2Mg + O2 —> 2MgO
2K + 2Cl —> 2KCl
Decomposition
A single compound is broke down into simpler substances.
Examples
2HgO —> 2Hg + 2O
2NaN3 —> 2Na + 3N2
Single Replacement
The atoms of one elements replace the atoms of a second element in a compound
Examples
2K + H2O —> 2KOH + 2H
Zn + Cu(NO3)2 —> Cu + Zn(NO3)2
Double Replacement
Exchange of positive ions between 2 compounds
Examples
Na2S + Cd(NO3)2 —> CdS + 2NaNO3
2NaCN + H2SO4 —> 2HCN + Na2SO4
Combustion
When the supply of oxygen is low, the combustion will not be completed, allowing the possibility that carbon(soot) and/or carbon monoxide gas will be among the products
A complete combustion of a hydrocarbon produces carbon dioxide and water.
Examples
C2H6 + 3O2 —> 2CO2 + 3H2O
2C8H18 + 25O2 —> 16CO2 + 18H2O
Net Ionic Reactions
Shows only spectator ions, ions that are the same on both sides of the equation, involved in a chemical reaction and is balanced with respect to both mass and charge
Predicting Products
By using the general rules for solubility of ionic compounds, you can predict the formation of a precipitate.
If a substance is soluble, then it is aqueous and will not form a precipitate.
If it is insoluble, than a precipitate will form in the new solution.