The process by which one or more substances are changed into one or more different substances CHEMICAL REACTIONS

Word Equations To write a word equation, 1. Write the names of the reactants to the left of the arrow separated by plus signs; 2. Write the names of the products to the right of the arrow, also separated by plus signs. Reactant + Reactant  Product + Product

EXAMPLE Methane + Oxygen  Carbon dioxide + Water

EXAMPLE 2 Iron + Oxygen  Iron(III) Oxide

EXAMPLE 3 Hydrogen Peroxide  Water and Oxygen

Skeleton Equations Write the formulas of the reactants to the left of the yields sign (arrow) and the formulas of the products to the right. A skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products. Here is the equation for rusting: Fe + O 2  Fe 2 O 3

Formula Writing Practice WS

Catalyst A catalyst is a substance that speeds up the reaction but is not used up in the reaction Without catalyst With Catalyst

Important Symbols

Balancing Chemical Equations To write a balanced chemical equation, 1. Write the skeleton equation 2. Use coefficients to balance the equation so that it obeys the law of conservation of mass.  Remember you want the same number of atoms of each element on each side of the equation.

Example

Example 2

Example 3 -- Try on your own!!! Write a balanced chemical equation for the reaction in which sodium hydroxide and calcium bromide react to produce solid calcium hydroxide and sodium bromide. (The reaction occurs in water.) NaOH(aq)+CaBr 2 (aq) Ca(OH) 2 (s)+NaBr(aq) 2NaOH(aq)+CaBr 2 (aq) Ca(OH) 2 (s)+2NaBr(aq)

Summary Write a skeleton equation Count atoms Add/adjust coefficients Reduce coefficients to lowest possible ratio Check your work

Warm Up!! _____NaClO 3 → ____ NaCl + __O 2

Chemical Equations from Names Magnesium and Hydrogen Chloride produce Hydrogen and Magnesium Chloride Calcium Hydroxide and Lithium Chloride produce Lithium Hydroxide and Calcium Chloride Decompose Copper (II) oxide into Copper and Oxygen Aluminum and Iron (III) oxide produce iron and aluminum oxide combustion of Butane (C 4 H 10 ) in air to produce carbon dioxide and water

Warm Up ___AgNO 3 + __Ni  __Ni(NO 3 ) 2 + __Ag

The Five Types of Reactions Chemical Reactions Synthesis Decomposition Single Replacement Double Replacement Combustion

Spongebob Chemistry

Chemistry with A + B  AB Synthesis Reactions

1. Synthesis Reactions (Combination) Two or more reactants produce one product Examples: NH 3 + HCl  NH 4 Cl H 2 + O 2  H 2 O Ag + S  Ag 2 S Al + Cl 2  AlCl 3

Chemistry with AB  A + B Decomposition Reactions

2. Decomposition One reactant produces two or more products Examples Ag 2 O  Ag +O 2 PCl 5  PCl 3 +Cl 2 H 2 O 2  H 2 O +O 2 CuO  Cu +O 2

Chemistry with AB + C  AC + B Single Replacement

3. Single Replacement One element replaces another element Must consult the activity series

3. Single Replacement One element and one compound producing a different element and compound Examples Fe + H 3 (PO 4 )  H 2 + Fe 3 (PO 4 ) 2 H 2 + CuO  Cu + H 2 O Zn + HCl  H 2 + ZnCl 2 Cl 2 + KBr  Br 2 + KCl

Equations Activity Series Worksheet

Chemistry with AB + CD  AD + CB Double Replacement

4. Double Replacement A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds. Examples: Al(NO 3 ) 3 + NaOH  Al(OH) 3 + NaNO 3 PbCl 2 + Li 2 SO 4  PbSO 4 + LiCl ZnBr 2 + AgNO 3  Zn(NO 3 ) 2 + AgBr BaCl 2 + KIO 3  Ba(IO 3 ) 2 + KCl

4. Double replacement Three main products of a double replacement reaction Precipitate (solubility table) Water Gas

5. Combustion A combustion reaction Chemical change Element or a compound reacts with oxygen Producing energy in the form of heat and light

5. Combustion A hydrocarbon reacts with oxygen to produce carbon dioxide and water Examples: CH 4 + O 2  CO 2 + H 2 O C 6 H 12 O 6 + O 2  CO 2 + H 2 O