EQUATIONS Coefficients- 1. The big numbers in front of the compounds and/or elements in a chemical reaction. 2. Represent the number of moles of that compound or element in a chemical reaction

3. Example: 2H 2 + O 2  2H 2 O 2H 2 + O 2  2H 2 O All represent coefficients. This reads 2 moles of H 2 reacts with 1 mole of O 2 forms 2 moles of H 2 O

Subscripts- 1. Small numbers inside a chemical formula 2. Represent the relative number of atoms in a compound 3. Example: Mg(NO 3 ) 2 Mg(NO 3 ) 2 All represent subcripts. This means that this compound is made of 1 Mg and 2(NO 3 ). Each NO 3 is made up of 1 N and 3 O

 Symbols  + means reacts with when on the reactant side and means and on the product side  means yields or produces  Δ means heat is applied

TYPES OF CHEMICAL REACTIONS Five Types of Chemical Reactions Five Types of Chemical Reactions 1. Synthesis or direct combination 2. Decompostion or analysis 3. Single replacement 4. Double replacement 5. Combustion

SYNTHESIS OR DIRECT COMBINATION

 Definition- A reaction in which two or more substance form a compound  Identification –Look at the product side (right side) there will be only one product  H 2 O 2 B 2 I 2 N 2 Cl 2, all are elements.  Examples:  2H 2 + O 2  2H 2 O  4Al + 3O 2  2Al 2 O 3  Ca + Cl 2  CaCl 2

DECOMPOSITION OR ANALYSIS

 Definition- A reaction in which a compound is broken down.  Identification- Look at the reactants (left side) there will be one compound.  Examples:  2HgO  2Hg + O 2  2H 2 O  2H 2 + O 2  2KClO 3  2KCl + 3O 2

SINGLE REPLACEMENT

 Definition- A reaction in which one element reacts with one compound to form another element and another compound  Identification- Look at the reactants (left side) there will be one element and one compound Remember the diatomics, H 2 O 2 B 2 I 2 N 2 Cl 2, all are elements  Examples:  Zn + Cu(NO 3 ) 2  Cu + Zn(NO 3 ) 2  Cu + 2 AgNO 3  2Ag + Cu(NO 3 ) 2  Mg + 2HCl  H 2 + MgCl 2

DOUBLE REPLACEMENT

 Definition- When two compounds react and form two other compounds  Identification- Look at the reactants (left side) there will be two compounds.  Examples:  NaOH + HCl  NaCl + HOH  AgNO 3 + NaCl  AgCl + NaNO 3  3CaBr 2 + 2Na 3 P  Ca 3 P 2 + 6NaBr

COMBUSTION

 Definition- A reaction in which an organic compound is burned and the products are always carbon dioxide and water  Organic compound- a compound composed of carbon and Hydrogen  Identification- Look at the reactants and look for O 2 also the products will be CO 2  Identification- Look at the reactants and look for O 2 also the products will be CO 2 and H 2 O  Examples  CH 4 + O 2  CO 2 + 2H 2 O  C 3 H 8 + 5O 2  3CO 2 + 4H 2 O

BALANCING EQUATIONS  Equations are balanced to obey the Law of Conservation of Mass.  To balance an equation coefficients are added so that the number of atoms on each side is constant  YOU CAN NEVER CHANGE SUBSCRIPTS TO BALANCE.

REACTION STOICHIOMETRY-REVISTED Steps for mole-mole problems a. Copy the balanced equation(we will use this as a “work area” b. Place the given number of moles above that compound in the balanced equation. c. Place an X above the unknown substance in the balanced equation d. Set up and solve a mole-coefficient ratio

 Example:  Hydrogen and oxygen react to produce water according to the following equation:  2H 2 + O 2  2H 2 O. How many moles of oxygen gas needs to be reacted to produce  7.5 moles of water?   2H 2 + O 2  2H 2 O  Answer:3.75 moles of O 2