Ch 6.1 Chemical Reactions

1
Ch 6.1Chemical Reactions
2
Objectives For this Chapter

• Understand parts to a chemical equation
  (reactants, products, yeild sign, double arrow)
• Conservation of matter is expressed through
  balancing chemical equations
• Describe difference between endothermic and
  exothermic reactions

3
Review from Ch 2

• Chemical Change Atoms in the reactants are
  rearranged to form one or more different
  substances
• Old bonds are broken new bonds form
• Ex)
• Fe and O2 form rust (Fe2O3)
• Ag and S form tarnish (Ag2S)

4
Basic Chemical Equation -Objective

• ______ _______ __________

Reactants
Products
5
(No Transcript)
6
Chemical Reaction

• A process in which at least one new substance is
  produced as a result of a chemical change

7
Signs of a chemical reaction

• In nature grow, ripen, decay, burn
• In the lab bubbles, change in color, precipitate
  forms, light and heat produced

8
(No Transcript)
9

• 1. The hydrogen peroxide oxidizes the phenyl
  oxalate ester, resulting in a chemical called
  phenol and an unstable peroxyacid ester.
• 2. The unstable peroxyacid ester decomposes,
  resulting in additional phenol and a cyclic
  peroxy compound.
• 3. The cyclic peroxy compound decomposes to
  carbon dioxide.
• 4. This decomposition releases energy to the
  dye.
• 5. The electrons in the dye atoms jump to a
  higher level, then fall back down, releasing
  energy in the form of light.

10
Energy and Reactions

• Energy needed to break bonds and form new
  compounds
• Energy is released when new compounds are formed
• Energy is conserved. Total energy before
  reaction total energy of products

11

• Objective
• Exothermic reaction - reaction that gives off
  heat energy feels hot
• Endothermic reaction - reaction that absorbs heat
  energy feels cold

12
(No Transcript)