Chemical Reactions

1
Chemical Reactions

• Chapter 10

2
Reactions Equations

• Chemical Rxn process by which atoms are
  rearranged to form different substances
• Indicated by
• Temp. change
• Color change
• Odor/gas bubbles produced
• Appearance of a solid (precipitate)

3
Representing Chemical Reactions

• Represented using equations
• Word equations
• Iron (s) chlorine (g) ? iron(III) chloride (s)
• Skeleton equations
• Fe (s) Cl2 (g) ? FeCl3 (s)
• Chemical equations must show that mass is
  conserved (balanced)
• 2Fe (s) 3Cl2 (g) ? 2FeCl3 (s)
• Reactants left side of yield sign starting
  substances
• Products right side of yield sign substances
  formed

4
Balancing Chemical Equations

• Coefficient number in front of chemical formula
• Steps for balancing
• Write skeleton equation
• Write atom inventory
• Add coefficients to make of atoms of reactants
  of atoms of products
• Write coefficients in lowest possible ratio
• NEVER change subscripts
• Check your work
• Practice p. 282 4-6

5
Classifying Chemical Reactions

• Synthesis two or more substances react to
  produce a single product
• A B ? AB
• Ex 2Na (s) Cl2 (g) ? 2NaCl (s)
• Decomposition single compound breaks down into
  two or more substances
• AB ? A B
• Ex 2NaN3 (s) ? 2Na (s) 3N2 (g)
• Practice p. 285 14-15, p. 286 18-19

6
Classifying Cont

• Single Replacement atoms of one element replace
  atoms of another element
• A BX ? AX B
• Ex Cu (s) 2AgNO3 (aq) ? 2Ag (s) Cu(NO3)2
  (aq)
• Only certain elements can replace another element
  (depends on reactivity)
• Activity series list of elements reactivities
  p. 288
• an element can only replace one beneath it
• To see if a reaction will occur, check activity
  series
• Practice p. 289 21-23

7
Classifying Cont

• Double Replacement exchange of positive ions
  b/t compounds
• AX BY ? AY BX
• Ex 2NaOH (aq) CuCl2 (aq) ? 2NaCl (aq)
  Cu(OH)2 (s)
• Practice p. 291 24-26
• Combustion oxygen combines with a substance
  releases energy in the form of heat light
• Ex CH4 (g) 2O2 (g) ? CO2 (g) H2O (g)
• Practice p. 285 17