Presentation Transcript
Chemical Equations and Reactions :Chemical Equations and Reactions Chapter 8
Objectives for today :Objectives for today List three observations that suggest a chemical reaction has occurred
List three requirements for correctly written chemical equations
Write word equations
Balance a formula equation by inspection
Classify chemical reactions
Indications of a chemical reaction :Indications of a chemical reaction Evolution of heat and light
Production of a gas
Formation of a precipitate
Color change
Characteristics of a Chemical Equation :Characteristics of a Chemical Equation The equation must represent all the known facts
The equations must contain the correct formulas for the reactants and products
The law of conservation of mass must be satisfied
Types of Reactions :Types of Reactions Synthesis
Decomposition
Single replacement
Double replacement
Combustion
Synthesis :Synthesis Synthesis reaction also know as composition
A + X ïƒ AX
2Mg + O2 ïƒ 2MgO
Decomposition :Decomposition Decomposition –one compound undergoes a reaction that produces two or more simpler substance
AX ïƒ A + X
2H20 ïƒ 2H2 + O2
Single replacement reaction :Single replacement reaction one element replaces a similar element in a compound
A + BXïƒ AX + B
Y + BX ïƒ BY + X
Mg + 2HCl ïƒ H2 + MgCl2
Double Replacement reaction :Double Replacement reaction the ions of two compounds exchange places in an aqueous solution to form two new compounds
a. AX + BY ïƒ AY + BX
b. 2KI + Pb(NO3)2 ïƒ PbI2 +2KNO3
Combustion :Combustion a substance combines with oxygen releasing a large amount of energy in the form of light and heat
burning of propane
C3H8 + 5O2 ïƒ 3CO2 + 4H2O