1. 1
Chemical
Reactions

2. 2
GOALS
1. Relate how the Law of Conservation of Matter is used to determine chemical composition in chemical reactions.
2. Experimentally determine indicators of a chemical reaction specifically precipitation, gas evolution, water production, and changes in energy to the system.
3. Identify and balance the following types of chemical equations:
• Synthesis • Decomposition
• Single Replacement • Double Replacement
• Combustion

3. Chemical Reactions 3
A chemical reaction is a change in which one or more substances are converted into new substances.
Rearrangement of bonds in compounds and molecules.
Chemical Equations make it possible to see clearly what is happening during a chemical reaction

4. Visualizing Chemical Reactions4
Visualizing Chemical Reactions
Chemical Reactions are simply the rearrangement of bonds between molecules.

5. Chemical equations are a shorthand way to show chemical reactions.
Reactants
Products
H2 + O2
H2O
This is a skeleton equation. It does not show the amounts 5

6. Chemical Equations (more details)5
Chemical Equations (more details)
Physical States can be shown by subscripts in parentheses.

7. 6

8. 7 Write the skeleton equations for the following:
1) Hydrogen peroxide  Water + Oxygen
2) Methane + Oxygen  carbon dioxide + water
3) Aluminum and iodine react to form aluminum iodide
4) Hydrogen iodide gas breaks down into hydrogen gas and iodine gas.

9. The mass of the products always equals the mass of the reactants
During a chemical reaction, mass is conserved.
Law of Conservation of Mass
The mass of the products always equals the mass of the reactants
Antoine Lavoisier 8

10. The mass of the products always equals the mass of the reactants
Law of Conservation of Mass
The mass of the products always equals the mass of the reactants 9

11. 2 Hydrogen atoms & one Oxygen atom10
Showing Conservation of Mass in Chemical Formulas
H2 + O2
H2O
Does this meet the Conservation of Mass Law?
2 Hydrogen atoms
2 Oxygen atoms
2 Hydrogen atoms & one Oxygen atom
Must Balance the Equation to show Conservation of Mass.

12. 11
Can add coefficients to Balance equations. 2
H2 + O2 2
H2O 4 2 2 2 4 1 2
Balanced!!
Steps:
1. Count Atoms on both sides
2. If not Balanced, add coefficients to balance.
3. Recount atoms after adding each coefficient.
4. Keep adding coefficients until balanced.
5. Check coefficients to make sure they are the SMALLEST whole number..

13. Balancing Equations Practice12
Balancing Equations Practice
____ K + ____ Cl2  ____ KCl
____ N2 + ____ H2  ____ NH3
____ N2 + ____ F2  ____ NF3
____ P4 + ____ Br2  ____ PBr3
____ GaF3 + ____ Cs  ____ CsF + ____ Ga
____ Al + ____ HCl  ____ H2 + ____ AlCl3
____ SO2 + ____ Li2Se  ____ SSe2 + ____ Li2O
____ Na3P + ____ CaF2  ____ NaF + ____ Ca3P2
____ AgNO3 + ____ Li  ____ LiNO3 + ____ Ag
____ CH4 + ____ O2  ____ CO2 + ____ H2O
____ BaS + ____ PtF2  ____ BaF2 + ____ PtS
____ Pb(OH)2 + ____ HCl  ____ H2O + ____ PbCl2
____ AlBr3 + ____ K2SO4  ____ KBr + ____ Al2(SO4)3
____ Na3PO4 + ____ CaCl2  ____ NaCl + ____ Ca3(PO4)
____ LiNO3 + ____ ____ CaBr2  ____ Ca(NO3)2 + ____ LiBr

14. Writing and Balancing Formulas For Reactions13
Writing and Balancing Formulas For Reactions
Steps
Determine correct formulas for all reactants and products.
Write the Skeleton equation.
Use coefficients to balance the equation.
EX: Solid carbon and oxygen gas react to form carbon dioxide gas.
EX: Aluminum sulfate reacts with calcium hydroxide to produce aluminum hydroxide and calcium sulfate.

15. Writing Formulas Practice14
Writing Formulas Practice
Aluminum metal dissolves in an aqueous solution of sulfuric acid to form hydrogen gas bubbles and a solution of aluminum sulfate. (don’t forget states of matter)
Al (s) + H2SO4 (aq)  H2 (g) + Al2 (SO4)3 (aq)
Balanced: 2Al (s) + 3H2SO4 (aq)  3H2 (g) + Al2(SO4)3 (aq)

16. 15
More Practice
Potassium metal and chlorine gas combine to form potassium chloride.
2 K + Cl2  2 KCl
Aluminum and hydrochloric acid react to form aluminum chloride and hydrogen gas.
2 Al + 6 HCl  3 H2 + 2 AlCl3
Zinc and lead (II) nitrate react to form zinc nitrate and lead.
Zn + Pb(NO3)2  Zn(NO3)2 + Pb
Aluminum bromide and chlorine gas react to form aluminum chloride and bromine gas.
2 AlBr3 + 3 Cl2  2 AlCl3 + 3 Br2

17. Types of
Chemical
Reactions 16

18. 17
Chemical Reactions
You start with one or more compounds and turn it into different compounds.
Vapors of hydrogen chloride in a beaker and ammonia in a test tube meet to form a cloud of a new substance, ammonium chloride.
Indicators of a chemical Reaction
Bubbling (evolution of a gas)
Color Change
Emission of heat and/or light
Formation of new substance
Precipitate
Temperature change

19. Synthesis (combination)18
5 Types of Chemical Reactions
Synthesis (combination)
Decomposition
Single Replacement
4. Double Replacement
5. Combustion

20. Synthesis 2H2 + O2 2H2O A + B AB Cu + O CuO 19 “to make”
2 or more smaller chemical substances combine into a new, larger compound.
“to make”
A + B AB
Cu + O CuO
2H2 + O H2O

21. Decomposition 2H2O 2H2 + O2 NaOH Na + OH AB A + B 20 “to breakdown”
Animation
Decomposition
One larger chemical
compound breaking up
into 2 or more
smaller substances.
“to breakdown”
Usually require energy
AB A + B
2H2O H O2
NaOH Na + OH

22. Single Replacement A + BC AC + B Cu+AgNO3 Cu(NO3)2+ 2Ag
When one element replaces another element in a compound
The more reactive metal will always replace the less reactive metal. 20
A + BC AC + B
Cu+AgNO3 Cu(NO3)2+ 2Ag
Mg(s) +2HCl(aq) MgCl2(aq) +H2 (g)
-The Mg bumps out the H+1 & forms Mg+2 ion in solution

23. The more reactive metal will always replace the less reactive metal.
Single Replacement
The more reactive metal will always replace the less reactive metal.
Metal replaces hydrogen or another metal
use the activity series to predict whether or not certain reactions will occur.
specific metal can replace any metal listed below it 21

24. Single-Replacement Reactions22
Single-Replacement Reactions
Predict the products that will result when these reactants combine, and write a balanced chemical equation for each reaction.
a. Fe(s) + CuSO4 (aq) →
b. Br2 (l) + MgC l2 (aq) →
c. Mg(s) + AlCl3 (aq) →

25. 23

26. Predict the outcome of the reaction
2Fe (s) + 3NiCl2 (aq) 
2Fe (s) + 3CoCl2 (aq) 
2Fe (s) + 3Pb(NO3)2 (aq) 
2Fe (s) + AlCl3 (aq) 
2Fe (s) + FeCl3 (aq)
2FeCl3 (aq) + Ni (s)
2FeCl3 (aq) + 3Co (s)
2Fe(NO3)3 (aq) + 3Pb (s)
No reaction
No reaction 24

27. Single Replacement
Animation
Clip

28. Double Replacement AB + CD AD + CB Ba(NO3)2+KSO4 2KNO3 + BaSO4
Positive Ion of One compound replaces the positive ion of another compound and a Precipitate is formed.
AB + CD AD + CB
Ba(NO3)2+KSO KNO3 + BaSO4
**start with 2 AQUEOUS SOLUTIONS,
the cations switch anions with each other. 25
Clip

29. Double Replacement 26 Generally takes place in an aqueous solution
1 of the following is usually true:
Precipitate forms
One of the products is a gas
One of the products is a molecular compound such as water. 26

30. Clip
Animation 27

31. 28

32. 29
Combustion
Chemical change in which an element or compound reacts with oxygen, often producing energy in the form of heat or light
Always involves oxygen as a reactant.
CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
2C4H10 (g) +18O (g) 8CO (g) +10H2O(g)
Combustion reactions are almost always exothermic (i.e., they give off heat).

33. Review 30

34. Identification of Reactions Practice
2 C6H O2 --> 12 CO H2O
2 C2H2 + 5 O2 --> 4 CO2 + 2 H2O
8 Cu + S8 --> 8 CuS
P4 + 5 O2 --> 2 P2O5
H2CO3 --> H2O + CO2
2 NaClO3 --> 2 NaCl + 3 O2
2 AgNO3 + Ni --> Ni(NO3)2 + 2 Ag
Ca + 2 HCl --> CaCl2 + H2
Ca(C2H3O2)2 + Na2CO3 --> CaCO3 + 2 NaC2H3O2
BaCO3 --> BaO + CO2
4 Cr + 3 O2 --> 2 Cr2O3
Cu(OH)2 + 2 HC2H3O2 --> Cu(C2H3O2)2 + 2 H2O
C3H8 + 5 O2 --> 3 CO2 + 4 H2O
3 AgNO3 + K3PO4 --> Ag3PO4 + 3 KNO3
2 K + 2 H2O --> 2 KOH + H2 C C S S D D SD SD DD D S DD C DD 31 SD