The main tasks of Chap 8 Sect 1 - Writing reactions from word problems – challenging Sect 2 - Balance Equationseasiest Sect 3 - Classify Equations, Complete.
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The main tasks of Chap 8
Sect 1 - Writing reactions from word problems – challengingSect 2 - Balance Equations—easiest Sect 3 - Classify Equations, Complete
Equations—challengingSect 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 producedCombustion of carbon compounds yield carbon dioxide(CO2) and water (H2O ).• Mg + O2 MgO• CH4 + O2 CO2 + H2O
Synthesis Reactions
Two or more elements or compounds combine to form ONE PRODUCT.• Mg + O2 MgO• H2 + O2 H2O• )()()( 4223 aqSOHlOHgSO
Decomposition Reactions
ONE REACTANT (compound) breaks into elements or smaller compounds.• H2O H2 + O2
• MgO Mg + O2
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 + ELEMENTThere 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 + AgNO3 Cu(NO3)2 + Ag
Single Displacement subtype:ANIONIC REPLACEMENT:
• If the Element is a Non-metal, it replaces the non-metal in the compound.
• Cl2 + NaBr NaCl + Br2
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= doesn’t 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) + AgNO3 (aq)
AgCl (s) + NaNO3(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) + NO3- (aq)
AgCl (s) + Na+(aq)+ NO3-(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 H2O(l).
This is called a neutralization reaction.The water H2O(l) stays together like insoluble
solids. So you keep it in the Net Ionic equation.
Ex. H+ + OH- H2O
Example: Complete and Net Ionic Equations page 1
Cu(NO3 )2 (aq) + NaOH(aq) ????1) Write Complete Molecular Equation: Cu(NO3 )2 (aq) + NaOH(aq) Cu(OH)2 (s) + NaNO3 (aq)
2) Write Complete Ionic Equation: [separate all (aq), put charges on ions; keep solids together.]
Cu+2(aq) +2NO3 -1(aq) + 2Na+1 (aq) + OH-1 (aq)
Cu(OH)2 (s) + 2Na+1 (aq) + 2NO3 -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)
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