Chemical Reactions

1
Chemical Reactions

• Chapter 9 p. 281-315

2
Vocabulary

• Chemical reaction
• Reactant
• Product
• Subscript
• coefficient

• Creates new substances
• Left of the ?
• Right of the ?
• F2
• 2CO

3
Skeleton Equation8 Fe S8 ---gt 8 FeS

• Word Equation
• Iron and sulfur react to form iron sulfide

4
Tips for Writing Skeleton Equations (cont.)

• When they are free elements (not in a compound)
  diatomic elements must be written with a
  subscript of 2.
• Sir BrINClHOF
• Br2, I2, N2, Cl2, H2, O2, F2
• H2 O2 ? H2O correct ?
• H O ? H20 incorrect ?

5
Tips for Writing Skeleton Equations (cont.)

• Produces
• Reacts to form
• Yields
• The above words translate to ? in the chemical
  equation

• Be careful of equations written backwards
• Water is produced when hydrogen and oxygen react

6
Balancing Chemical Equations

• Tally to see how many atoms of each element are
  on each side (product reactant)
• Change the coefficients (never the subscripts)
  until the number of atoms of reactants equal the
  number of atoms of products

7
Balancing Chemical Equations

• Balance ternary compounds first
• Ex. Na2SO4
• Balance elements last
• Ex. O2, Mg
• Treat polyatomic ions as one unit
• Ex. NO3 -

8
Types of Chemical Reactions

• Synthesis
• Decomposition
• Single Replacement
• Double Replacement
• Acid Base
• Combustion

9
Links for Chemical Reactions

• http//www.usoe.k12.ut.us/CURR/Science/sciber00/8t
  h/matter/sciber/chemtype.htm

10
Synthesis Reactionsp. 289

• A B ? AB
• H2 O2 ? H2O
• H2O SO3 ? H2SO4

11
Combustion Reactionsp. 290

• CxHy O2 ? CO2 H2O
• C2H6 O2 ? CO2 H2O
• C6H12O6 O2 ? CO2 H2O
• Mg O2 ? MgO heat
• Exception to the rule

12
Decomposition Reactionsp. 292

• AB ? A B
• KClO3 ? KCl O2
• NaHCO3 ? Na2CO3 H2O CO2

13
Single Replacement Reactions p. 293

• A BX ? AX B
• AgNO3 Cu ? Cu(NO3)2 Ag
• KI Cl2 ? KCl I2

14
Double Replacement Reactions p. 296

• These are the same as the metathesis or
  precipitation reactions we did in the lab two
  weeks in a row?

15
Double Replacement Reactions p. 296

• AX BY ? AY BX
• AgNO3 KCl ? AgCl(s) KNO3
• Metathesis reaction
• HCl NaOH ? HOH NaCl
• Acid base reaction 

16
Reactions in aqueous solution p.
299-308

• Aqueous solution
• Solute
• Solvent

• In water (aq)
• What is dissolved
• (usually a solid)
• What does the dissolving what there is more of
  (often water)

17
Reactions in aqueous solution (cont) p.
299-308

• Complete ionic equation
• Spectator ions
• Net ionic equation

• Shows all particles in the solution
• Ions that do not react
• Net ionic equation minus spectator ions

18
What you need to know

• How to write skeleton and word equations
• How to balance equations
• How to classify the six types of reactions
  predict their products
• How to write net ionic equations