Chemical Reactions
Chemical Reactions Objectives
1.Classify and name compounds in chemical reactions
2.Describe chemical reactions in word and chemical
equations.
3.Balance chemical equations based on the Law of
Conservation of Mass.
4.Identify and classify types of chemical reactions
and energy changes involved.
5.Predict products and energy changes in a chemical
reaction.
6.Identify and test factors that affect the rate of
chemical reactions.
Chemical Reactions
What is a chemical reaction?
• Use your background knowledge to explain
what a chemical reaction is.
• Think about chemical changes you have
observed in your surroundings.
• Think about chemical changes on an atomic
level.
Chemical Reactions
• Substances chemically interact to form different
substances.
• A substance can be an element or a compound.
• Chemical bonds are broken and created.
Example:
Iron chemically reacts with Oxygen to produce Iron(II) Oxide
Chemical Equations
Fe + O2 ------> FeO
Reactants:
• Starting substances.
• Chemically interact with one another.
• Usually located to the left of the arrow.
Products:
• Ending substances.
• Substances formed from the chemical reaction.
• Usually located to the right of the arrow.
Chemical Equations
Fe(s) + O2 (g) ------> FeO (s)
• (s)= substance in solid state
• (g)= substancein gaseous state
• (l)= substance in liquid state
• (aq)= substance dissovled in water.
(aqueous solution)
Chemical Reactions
Fe(s) + O2 (g) ------> FeO (s)
• Are atoms destroyed or created
during a chemical reaction?
• No, they are just rearranged to
produce new substances.
Law of Conservation Of Mass
• Matter is not created or destroyed.
• Matter is just rearranged.
(mass of reactants = mass of products)
That is why it is important to balance chemical
equations.
Conservation of Mass Lab
• Observe the conservation of mass lab, to
understand why it is important to balance
chemical equations.
Balancing Chemical Equations
2Fe(s) + O2 (g) ------> 2FeO (s)
Balancing Chemical Equations:
1. Add coefficients in front of substances, do
NOT change subscripts.
2. First balance elements that only appear once
on each side of the equation.
Balancing Chemical Equations
Chemical Reactions Bell Ringer
1. N2 (g) + H2(g) -------->
NH3(g)
a. What is the chemical name of one of the
reactants?
b. What is the chemical name of the product?
c. What state of matter is all the substances in this
reaction?
d. Balance the chemical equation if needed.
Type of
Anion
Monatomic
anion
(-ide
ending)
Polyatomic
anion
(-ite ending)
Polyatomic
anion
(-ate
ending)
Name of
Acid
hydro +
stem + ic
stem + ous
stem + ic
Balancing Chemical Equations
Types of Chemical Reactions
1. Synthesis (A+ B ----> AB)
2. Decomposition (AB------> A + B)
3. Single Replacement (A+ BC ---> B + AC)
4. Double Replacement (AB + CD ---> CB + AD)
5. Combustion (CxHx + O2 ----> CO2 + H2O)
6. Neutralization (Acid + Base--> H2O + Salt)
Chemical Reactions Objectives
1. Identify and classify types of chemical reactions.
2. Identify energy changes involved with chemical
reactions.
3. Predict products and energy changes in a chemical
reaction.
Synthesis (Combination) Reaction
• 2 or more substances chemically combine to form a
single substance.
• A + B ---> AB + energy
• Energy released into surroundings is more than
energy absorbed by the system.
( Energy of surroundings > Energy of system)
Decomposition Reaction
• A compound breaks down into simpler substances.
• AB + energy ----> A + B
• Energy of system > Energy of surroundings
Why?
Single Replacement Reaction
• An element replaces another element in a
compound.
• A + BC
--------> B + AC + energy
• Energy of surroundings > Energy of system
Double Replacement Reaction
• Exchange of cations between two compounds.
• AB + CD + energy ----> CB + AD + more energy
• Energy of Surrounding > Energy of System
Combustion Reaction
• Fuel (hydrocarbons) reacts with oxygen to
produce predictable substances and energy.
• CxHx + O2 ----> CO2 + H2O + ENERGY
• Energy of Surroundings > Energy of System
Neutralization
• Acid and Base react to produce predictable
products.
• Changes the pH to 7 (neutral).
Acid + Base -------> H2O + Salt
Salt: An ionic compound.
The cation comes from the base and the anion from
the acid.
Class Reminders:
• Acid Rain Article (15pts.)
• Balance Chemical Equations Worksheet (10pts.)
(balance and classify equations)
• Word Equation Worksheet (10pts.)
*3rd Quarter Ends: March 8th*
Chemical Reaction Lab
Purpose:
• Perform and observe types of chemical
reactions.
• Determine reactants and predict products.
• Classify chemical reactions.
• Balance chemical reactions.
• Write a formal lab report
Chemical Equations to Lab
Reaction Chemical Equation
1
2
3
4
5
6
7
8
Types of Chemical Reactions
1. Synthesis (A+ B ----> AB)
2. Decomposition (AB------> A + B)
3. Single Replacement (A+ BC ---> B + AC)
4. Double Replacement (AB + CD ---> CB + AD)
5. Combustion (CxHx + O2 ----> CO2 + H2O)
6. Neutralization (Acid + Base--> H2O + Salt)
Chemical Equations to Lab
Just need to check and see if they are balanced.
1. Mg + O2 ------>
2. Mg + HCl ---->
3. (NH4)2(CO3) -----> NH3 + CO2 + H2O
4. Ca(CO3) + HCl ----> CaCl2 + H2O + CO2
5. Zn + CuCl2 ---->
6. CuCl2 + Na3(PO4) --->
7. HCl + Na(OH) ----> H2O + NaCl
8. C2H6O + O2 ----->
Chemical Reaction Review
1. What are the coefficients that will balance the
chemical equation below?
AlCl3 + Na(OH) ----> Al(OH)3 + NaCl
a. 1,3,1,3
b. 3,1,3,1
c. 1,1,1,3
d. 1,3,3,1
2. What type of chemical reaction is in question 1?
3. Predict the product and balance if needed:
Ba (s) + O2 (g) ---------->
Balancing and Classifying Chemical Reactions
Chemical Equations to Lab
Just need to check and see if they are balanced.
1. Mg + O2 ------> MgO
2. Mg + HCl ----> MgCl + H2
3. (NH4)2(CO3) -----> NH3 + CO2 + H2O
4. Ca(CO3) + HCl ----> CaCl2 + H2O + CO2
5. Zn + CuCl2 ----> ZnCl2 + Cu
6. CuCl2 + Na3(PO4) ---> Cu3(PO4)2 + NaCl
7. HCl + Na(OH) ----> H2O + NaCl
8. C2H6O + O2 -----> CO2 + H2O
Conclusion
Needs to include the following:
• Identify and explain the types of reactions obsvd. ?
• Which reaction(s) did you like the best and why?
• Based on data section explain which reactions
were exothermic and endothermic.
• What did you learn from this lab?
Predicting Products in a Chemical Reaction
a. Ca + N2 --------> ?
b. Cu2S ------->
?
c. NaBr + F2 ------> ?
d.CH4 + O2
----->
Balancing and Classifying Equations Quiz
Types of Chemical Reactions
1. Synthesis
2. Decomposition
3. Single Replacement
4. Double Replacement
5. Combustion
6. Neutralization
Predicting Products
• Check my webpage for correct chemical formulas
prior to balancing.
Predicting Single Replacement Reactions
• An Activity Series can help us predict if a single
replacement reaction will take place.
Activity Series Lab Hypothesis
CuCl2(aq)
Copper (s)
Magnesium (s)
Zinc (s)
Calcium (s)
Ag(NO3)
HCl (aq)
dH(OH) (l)
Activity Series Lab
• Complete conclusion
• Complete Post Lab Questions
Activity Series Lab
1. Using the Activity Series Table, predict whether
the following single replacement reactions
would occur:
a. Li + MgCl
b. Hg + Na3P
c. Pb + HF
Predicting Single Replacement Reactions
• An Activity Series can help us predict if a single
replacement reaction will take place.
Activity Series Lab
• Complete conclusion
• Complete Post Lab Questions
Chemical Reaction Study Guide Changes
1. Vocabulary words: Thermochemistry
10. HgO + energy ------> Hg + O2
11. Fe + F2 ----------> FeF3 + energy
12. CH4 + O2 ---------> CO2 + H2O + energy
15. K(OH) + H3(PO4) ------->
18. Omit last word equation. 
Chemical Reaction Review
1. What are the coefficients that will balance the
chemical equation below?
AlCl3 + Na(OH) ----> Al(OH)3 + NaCl
a. 1,3,1,3
b. 3,1,3,1
c. 1,1,1,3
d. 1,3,3,1
2. What type of chemical reaction is in question 1?
3. Predict the product and balance if needed:
BaS + Mg ---------->
Thermochemistry
Energy changes that occur within reactions.
Endothermic Reactions
Exothermic Reactions
Exothermic Reaction
• Energy absorbed < Energy released.
• The chemical reaction becomes cooler and its
surroundings gets warmer.
• Energy is on the product side.
• C8H18 + O2 -------> CO2 + H2O + energy
Endothermic Reactions
•
•
Energy absorbed > Energy released
Chemical reaction gets warmer and its
surroundings gets cooler.
• Energy is on the reactant side.
Ex. Photosynthesis
Chemical Reaction Energy Diagram
Chemical Reaction Energy Diagram
•Activation Energy (Ea): The amount of kinetic energy
needed to be absorbed from the surroundings for the
chemical reaction to occur.
H : The amount of kinetic energy released into the
into the surroundings.
Chemical Reaction Energy Diagram
Exothermic Reaction
Chemical Reaction Energy Diagram
Endothermic Reaction
Activation
Energy
Chemical Reactions Objectives
1.Classify and name compounds in chemical reactions
2.Describe chemical reactions in word and chemical
equations.
3.Balance chemical equations based on the Law of
Conservation of Mass.
4.Identify and classify types of chemical reactions and
energy changes involved.
5.Predict products and energy changes in a chemical
reaction.
6.Identify and test factors that affect the rate of
chemical reactions. (Chpt. 18.1)
Chemical Reaction Rates
Assignment:
Read Section: 18.1 in textbook (pg. 540)
Chemical Reactions Rates
• Reaction Rates = how fast the reactants
chemically change into the products.
• Collision Theory: Reactant particles will react to
form products when they collide and exchange
enough kinetic energy with one another.
Rates of Chemical Reactions
• What are factors that can affect the rates of
reactions?
Rates of Chemical Reactions
• What are factors that can affect the rates of
reactions?
• Temperature
• Concentration of Reactants
• Surface Area of Reactants
• Catalysts
• Inhibitors
Temperature of Reaction
What if we increase the temperature of a
reaction?
What if we decrease the temperature of a
reaction?
Concentration
• Increase concentration of reactants?
• Decrease concentration of reactants?
Surface Area
• Increase surface area of reactants?
• Decrease surface area of reactants?
Catalysts
• Catalysts speed up reactions, but they are not
apart of the chemical reaction.
Ex. Enzymes keep your body temperature
around 37oC (98 oF) by speeding up important
biological reactions.
Catalyst and Energy Change
Inhibitors
• Inhibitors slow down a chemical reaction.
• Inhibitors bind to a catalyst and prevent it
from speeding up a reaction.
Ex. Preservation of food. Antioxidants prevent
foods from becoming stale or moldy.
Soln. A Concentration vs. Avg. Reaction Times
Time G1
Conc
G2
G3
G4
G5
G6
G7
A1
7
6
9
9.4
5
3
4.0
A2
6.4
9
9.76 9.5
8
9
15.2
A3
4.8
12
9.4
6
22.6
A4
8.9
15
15.0 19.1 19.1 14
13.4 12
24.3
Avg.
Activation Energy
• Activation energy = minimum energy
colliding reactants must have for a reaction to
occur. (Energy hump.)
Catalyst and Energy Change