double replacement reaction: parts of two compounds switch places to form two new compounds two...
TRANSCRIPT
Double Replacement Reaction:
• Parts of two compounds switch places to form two new compounds
• Two reactants yield two products.
Al2(SO4)3 (s) + 3NH4OH (aq)
2Al(OH)3 (s) + 3NH4SO4 (aq)
MgSO4 (s) + 2NH4OH (aq)
Mg(OH)2 (s) + (NH4)2SO4 (aq)
Double Replacement(Swap ‘hats’)
Single Replacement(new couple)
Synthesis( 2 becomes 1)
+Decomposition(1 becomes 2)
Which type of reaction is shown?
2 Ca (s) + O2 (g) 2 CaO (s)
MgCO3 (s) MgO (s) + CO2 (g)
Cu (s) + 2 AgNO3 (aq) Cu(NO3)2 (aq) + 2 Ag (s)
3AgNO3 (aq) + Na3PO4 (aq) Ag3PO4 (s) + 3NaNO3 (aq)
Synthesis
Single Replacement
Decomposition
Double Replacement
2 HgO (s) 2Hg (l) + O2 (g)
Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g)
BaCl2 (aq) + Na2SO4 (aq) BaSO4 (s) + 2 NaCl (aq)
H2 (g) + Cl2 (g) 2 HCl (g)
Double Replacement
Single Replacement
Decomposition
Synthesis
Heat and Chemical Change
Active IngredientsKClNaClNH2CONH2 (urea)C7O6H14 (methyl-D-glucopyranoside; a surfactant)
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What have we learned?
Sometimes heat is given off during a chemical reaction.This makes it feel hotter.
Sometimes heat is absorbed during a chemical reaction.This makes it feel colder.
What causes it to be different?
• Chemical bonds contain energy.
• Add the energy of all of the bonds in the reactants together to find their total energy.
• Add the energy of all of the bonds in the products together to find their total energy.
• If the two numbers aren’t the same (and they almost never are), then there will be heat energy given off or taken in.
2 H2 + O2 2 H2O
Energy
2 H2 + O2
2 H2O
•If the products contain less energy, energy must have been given off during the reaction.
Energy barrier
2 H2 + O22 H2O
Energy
2 H2 + O2
2 H2O
•If the products contain more energy, energy must have been absorbed during the reaction.
Energy barrier
If heat energy is given off during a reaction, it is called an EXERGONIC or an EXOTHERMIC REACTION.
Heat exits = exergonic = exothermic
Exergonic reactions can be recognized by a temperature INCREASE.
If heat energy is absorbed during a reaction, it is called an ENDERGONIC or an ENDOTHERMIC REACTION.
Heat enters = endergonic = endothermic
Endergonic reactions can be recognized by a temperature DECREASE.
Rates of Reactions
Vs.
December 1977 in Westwood, LAGrain elevator explosion
August 10, 2003 in Columbus, OHFlour mill explosion
January 29, 2003 in Kinston, NC West Pharmaceutical Services
chemed.chem.purdue.edu/demos/main_pages/5.14.html
QuickTime Movie
OHCOO)OHC( 222n6126 xsflour
Air-borne dust ???
Flour
Pile Slow
Rate of Reaction
[dust] > 50 g/m3
NC Competency Goal 4.03
Assess reaction rates and factors that affect reaction rates.
And by the letter
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