Presentation on theme: "The main tasks of Chap 8 Sect 1 - Writing reactions from word problems – challenging Sect 2 - Balance Equationseasiest Sect 3 - Classify Equations, Complete."— Presentation transcript:
The main tasks of Chap 8 Sect 1 - Writing reactions from word problems – challenging Sect 2 - Balance Equationseasiest Sect 3 - Classify Equations, Complete Equationschallenging Sect 4 – Write Net Ionic equations
Classifying Reactions You will learn to recognize the different types of reactions AND How to complete products (predict).
Combustion Reactions Burning Oxygen is a reactant. Energy is produced Combustion of carbon compounds yield carbon dioxide(CO 2 ) and water (H 2 O ). Mg + O 2 MgO CH 4 + O 2 CO 2 + H 2 O
Synthesis Reactions Two or more elements or compounds combine to form ONE PRODUCT. Mg + O 2 MgO H 2 + O 2 H 2 O
Decomposition Reactions ONE REACTANT (compound) breaks into elements or smaller compounds. H 2 O H 2 + O 2 MgO Mg + O 2
Displacement Reactions Also called Replacement reactions Single Displacement/Replacement – Use the Activity series Double Displacement/Replacement – Precipitation Reactions Use the Solubility Rules – Acid Base Reactions
Single Displacement Part of an ionic compound is removed and replaced by a new element. ELEMENT + COMPOUND COMPOUND + ELEMENT There are 2 subtypes of single replacement reactions. -Cationic replacement -Anionic replacement
Single Displacement subtype CATIONIC REPLACEMENT : If the Element is a Metal, it replaces the metal in the compound. Cu + AgNO 3 Cu(NO 3 ) 2 + Ag
Single Displacement subtype: ANIONIC REPLACEMENT : If the Element is a Non-metal, it replaces the non-metal in the compound. Cl 2 + NaBr NaCl + Br 2
Single Replacement Rxns To determine if a Single Replacement Reaction really happens, use the ACTIVITY SERIES reference sheet. If an element is higher on the chart, it will become a compound. If the higher element is already in a compound, then NO reaction occurs
Double Replacement Rxns Two Ionic Compounds that exchange partners. XY + AB AY + XB Only Positive with Negative Positive Ion listed first
Double Replacement Rxns To determine if the reaction occurs, use the SOLUBILITY RULES. A reaction occurs if a solid or water forms when two aqueous solutions of ionic compounds are mixed. If the products are both aqueous ionic compounds, then no reaction occurs.
Solubility Rules info. Soluble = dissolves in water = (aq) = clear Insoluble= doesnt dissolve in water = SOLID = (s) = cloudy = precipitate = ppt
Section 4: Net Ionic Equations Three ways to write the same equation (usually with double replacement rxns): 1. Complete Molecular Equation 2. Complete Ionic Equation 3. Net Ionic Equation
Dissolving (aq) separates the ions NaCl (s) in water NaCl (aq) NaCl (aq) means Na+(aq) + Cl- (aq) The Ions move separately in solution. In some equations we separate the ions and write the charges.
Complete Molecular Eqn This is what we have been doing. Write the compounds with the ions together. Example: NaCl (aq) + AgNO 3 (aq) AgCl (s) + NaNO 3 (aq)
Complete Ionic Eqns Write the aqueous compounds as separate ions. Be sure to put the CHARGES ON THE IONS! Keep the solid(insoluble) or water molecules together. Example: Na + (aq) + Cl - (aq) + Ag+ (aq) + NO 3 - (aq) AgCl (s) + Na+( aq) + NO 3 - (aq)
Net Ionic Equations Take the Complete ionic equation and remove any ion that is aqueous on both sides. These ions are called Spectator Ions. OR Find the Solid product or water, keep that part AND keep the reactant ions that made the solid or water. Ex: Ag + (aq) + Cl - (aq) AgCl(s)
Net Ionic Eqns with Acids and Bases( H+ and OH-) When acids (HA) and Bases (ZOH) mix, the H + and OH - combine to become H 2 O(l). This is called a neutralization reaction. The water H 2 O(l) stays together like insoluble solids. So you keep it in the Net Ionic equation. Ex. H + + OH - H 2 O
Example: Complete and Net Ionic Equations page 1 Cu(NO 3 ) 2 (aq) + NaOH (aq) ???? 1) Write Complete Molecular Equation: Cu(NO 3 ) 2 (aq) + NaOH (aq) Cu(OH) 2 (s) + NaNO 3 (aq) 2) Write Complete Ionic Equation: [separate all (aq), put charges on ions; keep solids together.] Cu +2 (aq) + 2NO 3 -1 (aq) + 2Na +1 (aq) + OH -1 (aq) Cu(OH) 2 (s) + 2Na +1 (aq) + 2NO 3 -1 (aq) And then…
Example: Complete and Net Ionic Equations page 2 3) Write Net Ionic Equation: [eliminate spectator ions, keep ions that make solid, keep solids.] Cu +2 (aq) + OH -1 (aq) Cu(OH) 2 (s)