Notes: Chemical Reactions

UNIT 4: Chemical Reactions – Stoichiometry and Thermodynamics
Part A: Chemical Reactions
Big Picture Ideas:

The identity of the reactants helps scientists to predict the products in a chemical reaction.
Quantitative relationships exist with all chemical reactions that allow scientists to predict amounts of products formed, reactants consumed, and percent yield based on theoretical maximum.

Big Picture Question:How can you predict the products in a chemical reaction?
Suggested Resources…
Homework Assignments
Classwork Assignments
Laboratory Activities
Formative Assessments
Textbook pages: Chapter 9
Websites:
Key Terms:

chemical reaction
chemical equation
reactants
yields
products
coefficient/mole
subscript
diatomic molecules
synthesis/direct combination
decomposition
single replacement/displacement
double replacement/displacement
combustion
activity series
aqueous
kinetics
catalyst
surface area

Directions: Use this information as a general reference tool to guide you through this unit. Don’t hesitate to ask your teacher for help!
By the conclusion of this unit, you should know the following:

There are five basic types of chemical reactions (S, D, SR, DR, Comb.) that exhibit distinct patterns for the prediction of products.
Experimental evidence can be used to identify products in a reaction.
All reactions follow the Law of Conservation of Matter (balancing equations).
Symbols are used to identify different aspects of a chemical reaction (states of matter, catalysts, heat, etc.).
Collision theory describes characteristics for a successful reaction.
Factors can be altered to affect the rate of a reaction (temperature, surface area, catalyst, concentration).

/ By the conclusion of this unit, you should be able to do the following:

Balance chemical reactions.
Identify type of chemical reaction.
Identify if a reaction will occur using an activity series.
Predict products for a reaction.
Write balance formula equation given chemical equation (words).
Using the collision theory, explain how altering the temperature, surface area, concentration and the addition of a catalyst affects the rate of a reaction.
Draw an energy diagram for both endothermic and exothermic reactions.

1. What type of reaction is it?

a. element + element 

b. ionic compound + ionic compound 

c. element + ionic compound 

d. compound 

e. compound + oxygen 

2. How can you tell if a chemical change has taken place? List examples.

3. Define a chemical reaction. Why must we balance chemical equations? (if it is a “must” there must be a “law” governing the concept).

4. Balance each reaction below. Identify each type the following reactions are:

a) NaOH(aq) + Pb(NO3)2(aq) --> NaNO3(aq) + Pb(OH)2(s)

b) CH4(g) + O2(g) --> CO2(g) + H2O(l)

c) Fe(s) + NaBr(aq) --> FeBr3(aq) + Na(s)

d) Pb(s) + O2(g) --> PbO (g)

e) Na2CO3(s) --> Na2O(s) + CO2(g)

5. Complete and balance each reaction below:

a) Mg + HCl  ______+ ______

b) C2H6 + O2  ______+ ______

c) CaF2 + Na2SO4  ______+ ______

d) Sr + N2 ______

6. List three factors effecting the rate of a chemical reaction. Know why they effect the reaction rate (collision theory!)

7. Describe the standard test for hydrogen, oxygen and carbon dioxide

NOTES: CHEMICAL REACTIONS

VOCABULARY:

Products result after reaction occurs

Reactantsstarting substances in a reaction

”yields”

+and

(s) solid

(l)liquid

(g)gas

(aq)aqueous – substance dissolved in water

Catalystspeads up a reaction by lowering activation energy

Activation Energy (Ea)starting amount of energy

ENERGY OF CHEMICAL REACTIONS:

Exothermic Reaction: ΔH is – Endothermic Reaction: ΔH = +

(heat is a “product”)(heat is a “reactant”)

KINETICS: RATE OF CHEMICAL REACTIONS

Collision Theory:reactants must collide with (1) at least the activation energy and with (2) the correct orientation

Factors Effecting Reaction Rate:

Temperaturequicker particles collide with energy and they collide more often (due to the high temperature)

Particle size (surface area)more surface area = more collisions = faster rate

Mixing/Stirringcreates more surface area = more collisions = faster rate

Nature of Reactionhow reactive the particles are

Adding a Catalyst or Inhibitorcatalyst – speeds up the reaction by lowering the activation energy; inhibitor – slows down reactions by preventing correct collisions

BALANCED CHEMICAL REACTIONS

Law of Conservation of Matter:matter cannot be created or destroyed (number of atoms of each element need to be the same on each side of the equation)

Try balancing these chemical reactions:**subscripts are used to write formulas**coefficients are used to balance**

a. 2 Na + H2SO4  Na2SO4 + H2

b. 2 K + Cl2  2 KCl

c. S8 + 8 O2  8 SO2

d. 3F2 + 2 FeBr3  2 FeF3 + 3Br2

e. 3H2SO4 + 2 Al  Al2(SO4)3 + 3H2

f. 2 C2H6 + 7 O2  4CO2 + 6H2O

g. 2 NaNO3 + Ca(MnO4)2  2 NaMnO4 + Ca(NO3)2

h. 3 P4 + 10 KClO3  10 KCl + 6 P2O5

WORD  FORMULA  BALANCED EQUATIONS

word equation: Hydrogen gas reacts with oxygen gas to form water

formula equation: ______H2 + O2 H2O______

diagram:

balanced reaction ______2 H2 + O22 H2O______

word equation: Magnesium reacts with hydrochloric acid solution (HCl in water) to form

magnesium chloride and hydrogen.

Formula equation: ______Mg + HCl  MgCl2 + H2 ______

diagram:

balanced reaction ______Mg + 2 HCl  MgCl2 + H2______

SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

Types of Reactions: Synthesis, Decomposition and Combustion

Synthesis – A + B  AB (1 product only)

Combination reaction (2 or more substances combine to form 1 product)

1 substance to the right of the 

Decomposition – AB  A + B (1 reactant only)

Breaking 1 substance down

Combustion of a hydrocarbon – CxHy + O2 CO2 + H2O

Hydrocarbon reacting with oxygen

Exothermic (burning releases heat)

Practice:

Balance each reaction below. Then identify the reaction type.

a. H2 + Br2  2 HBr____synthesis______

b. C4H8 + 6 O2  4 CO2 + 4 H2O___combustion______

c. 2 NaOH  Na2O + H2O_____decomposition______

d. Ba(ClO3)2  BaCl2 + 3 O2____decomposition______

HOMEWORK: BALANCING CHEMICAL REACTIONSNAME:

DATE:

1. ___P4 + _5__O2  _2__P2O5

2. _2__Al + _6__HCl  _2__AlCl3 + _3__H2

3. ___Al2(SO4)3 + _3__Ca(OH)2 _2__Al(OH)3 + _3__CaSO4

4. _8__H2S + _8__Cl2  ___S8 + _16__HCl

5. _3___Mg + ____N2  ____Mg3N2

6. _3___Fe + _4___H2O  ____Fe3O4 + _4___H2

7. _2___NaOH + ____Cl2  ____NaCl + ____NaClO + ____H2O

8. _2___C4H10 + _13___O2  _8___CO2 + _10___H2O

9. __2___CH3OH + __3___O2  _2___CO2 + __4___ H2O

HOMEWORK: SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS

1. Classify each equation below as synthesis, decomposition or combustion. Then balance each equation.

__decomposition______1. 2 NaClO3  2 NaCl + 3 O2

___synthesis______2. 2 Cu + S  Cu2S

___synthesis______3. 2 S + 3 O2  2 SO3

___combustion______4. 2 C3H6 + 9 O2  6 CO2 + 6 H2O

2. Classify each equation below as synthesis, decomposition or combustion. Write and balance the equation for the reaction.

___decomposition______1. potassium hydroxide  potassium oxide + hydrogenwater

2 KOH  K2O + H2O

___combustion______2. dicarbon tetrahydride + oxygen  carbon dioxide + water

C2H4 + 3 O2  2 CO2 + 2 H2O

___decomposition______3. lithium chlorate  lithium chloride + oxygen

2 LiClO3  2 LiCl + 3 O2

____synthesis______4. magnesium + nitrogen  magnesium nitride

3 Mg + N2  Mg3N2

___synthesis______5. aluminum burns in pure oxygen to form aluminum oxide

4 Al + 3 O2  2 Al2O3

____decomposition______6. sodium carbonate is heated to form sodium oxide and carbon dioxide

Na2CO3  Na2O + CO2

___synthesis______7. water and dinitrogen pentoxide combine to form nitric acid

H2O + N2O5  2 HNO3

First write and then balance the equation. Then identify the reaction type.

e. phosphorus + oxygen  tetraphosphorus decoxide

4 P + 5 O2 P4O10synthesis

f. pentane (C5H12) + oxygen  carbon dioxide + water

C5H12 + 8 O2  5 CO2 + 6 H2Ocombustion

g. magnesium chlorate  magnesium chloride + oxygen

Mg(ClO3)2  MgCl2 + 3 O2decomposition

h. when solid calcium carbonate is heated calcium oxide and carbon dioxide are formed

CaCO3  CaO + CO2decomposition

i. the formation of calcium nitride from calcium and nitrogen

3 Ca + N2 Ca3N2synthesis

j. sulfur trioxide mixes with water in the atmosphere to form sulfuric acid

SO3 + H2O  H2SO4synthesis
NOTES: SINGLE DISPLACEMENT REACTIONSDOUBLE DISPLACEMENT REACTIONS

1. Single Displacement Reactions (aqueous ONLY)element + compound

metals:

standard:A + BC  B + AC

example:Cu + 2 AgNO3 Ag + Cu(NO3)2

metal + acid:

standard:A + HC  H2 + AC

example:Zn + H2SO4 H2 + ZnSO4

metal + water:**replace metal with only 1 hydrogen in water!

standard:A + HOH  H2 + AOH

example:2Na + 2HOH  H2 + 2 NaOH

halogens:

standard:A + BC  C + BA

example:F2 + 2 NaCl  Cl2 + 2 NaF

2. Double Displacement (aqueous only)ion exchange reaction: compound + compound

standard:AB + CD  AD + CB

example:NaCl + AgNO3 NaNO3 + AgCl

3. Identify the reaction type for each reaction below. Then complete and balance the reaction.

_single displacement_ a. Ba + 2 AgNO3  Ba(NO3)2 + 2Ag

__single displacement______b. F2 + 2KI  2KF + I2

double displacement c. NaOH + CaCl2  _2 NaCl + Ca(OH)2

___single displacement d. Zn + H2SO4  ZnSO4 + H2

WRITING WORD EQUATIONS

__decomposition______1. aluminum chlorate  aluminum chloride + oxygen

2 Al(ClO3)3 9 O2 + 2 AlCl3

__SR______2. lithium + iron (III) nitrate  lithium nitrate + iron

3 Li + Fe(NO3)3  3 LiNO3 + Fe

__decomposition______3. magnesium carbonate  magnesium oxide + carbon dioxide

MgCO3  MgO + CO2

__synthesis______4. tin + nitrogen  tin (IV) nitride

3 Sn + 2 N2 Sn3N4

__SR______5. Zinc reacts with nitric acid to form zinc nitrate and hydrogen

Zn + 2 HNO3 Zn(NO3)2 + H2

__decomposition______6. calcium hydroxide breaks down to form calcium oxide and water

Ca(OH)2 CaO + H2O

WRITING WORD EQUATIONS WITH PREDICTING PRODUCTS

__synthesis______1. aluminum + oxygen 

4 Al + 3 O2 2 Al2O3

__SR______2. sodium + silver nitrate 

Na + AgNO3 NaNO3 + Ag

__SR______3. magnesium + hydrochloric acid 

2 Mg + 2 HCl  2 MgCl + H2

___DR______4. solutions of iron (III) nitrate + potassium sulfate are mixed 

2 Fe(NO3)3 + 3 K2(SO4)3 Fe2(SO4)3 + 6 KNO3

____SR______5. Chlorine gas is bubbled through a solution of lithium iodide 

Cl2 + 2 LiI  2 LiCl + I2
Fun With Predicting Reaction Products

Predict the products of each of the following chemical reactions. If a reaction will not occur, explain why not:

1)____ Ag2SO4 + __2__ NaNO32 AgNO3 + Na2SO4

2)__2__ NaI + ____ CaSO4CaI2 + Na2SO4

3)__2__ HNO3 + ____ Ca(OH)2 2 H2O + Ca(NO3)2

4)____ Zn + ___2__ HNO3  Zn(NO3)2 + H2

5)____ AlCl3 + ____ (NH4)3PO4 AlPO4 + 3 NH4Cl

6)___3_ Pb + ___2_ Fe(NO3)3 3 Pb(NO3)2 + 2 Fe

7)___2_ C3H6 + __9__ O2 6 CO2 + 6 H2O

8)__2__ Na + ____ CaSO4 Na2SO4 + Ca

CLASSIFICATION OF CHEMICAL REACTIONS

Classify the reactions below as sythesis, decomposition, single replacement or double replacement:

1. 2H2 + O2  2H2O____synthesis______

2. 2H2O  2H2 + O2____decomposition______

3. Zn + H2SO4  ZnSO4 + H2____SR______

4. 2CO + O2  2CO2_____synthesis______

5. 2HgO  2Hg + O2____decomposition______

6. 2 KBr + Cl2  2 KCl + Br2____SR______

7. CaO + H2O  Ca(OH)2____synthesis______

8. AgNO3 + NaCl  AgCl + NaNO3____DR______

9. 2 H2O2  2H2O + O2____decomposition______

10. Ca(OH)2 + H2SO4  CaSO4 + 2H2O_____DR______

11. Copper metal is put into a solution of silver nitrate. Solid silver precipitates, and copper (II) nitrate solution is formed.

___SR______

12. Methane gas burns in pure oxygen to give carbon dioxide and water

___combustion______

13. When sodium carbonate is heated, it breaks down to form sodium oxide and carbon dioxide. ___decomposition______

WRITING WORD EQUATIONS

a. lithium + nitrogen  lithium nitride

6 Li + N2  2 Li3N

b. aluminum + oxygen  aluminum oxide

4 Al + 3 O2  2 Al2O3

c. sodium carbonate  sodium oxide + carbon dioxide

Na2CO3  Na2O + CO2

d. zinc + phosphoric acid  zinc phosphate + hydrogen gas

3 Zn + 2 H3PO4  Zn3(PO4)2 + 3 H2

e. chlorine gas + lithium iodide  lithium chloride + iodine

Cl2 + 2 LiI  2 LiCl + I2

f. sodium hydroxide  sodium oxide + water

2 NaOH  Na2O + H2O

g. magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas

Mg + 2 HCl  MgCl2 + H2

h. solutions of iron (III) chloride and sodium hydroxide react to form iron (III) hydroxide and sodium chloride

FeCl3 + 3 NaOH  Fe(OH)3 + 3 NaCl

i. when sodium is added to water, sodium hydroxide and hydrogen gas are produced\

2 Na + 2 H2O  2NaOH + H2

j. when zinc is placed in a solution of lead (II) nitrate, zinc nitrate and solid lead metal are formed

Zn + Pb(NO3)2  Zn(NO3)2 + Pb

HOMEWORK – PRACTICE REACTION WRITING

Identify the reaction type for each reaction written below. Then write the balanced equation for each reaction.

____single displacement___ 1. Magnesium is placed in a solution of aluminum nitrate

3 Mg + 2 Al(NO3)3 3 Mg(NO3)2 + 2 Al

______synthesis______2. Calcium burns in pure oxygen.

2 Ca + O2  2CaO

____combustion hydrocarbon_____ 3. The combustion of propane (C3H8)

______C3H8 + 5 O2  3 CO2 + 4 H2O______

____single displacement_____ 4. Fluorine is bubble through a solution of sodium bromide

______F2 + 2 NaBr  2 NaF + Br2______

___double displacement______5. Solutions of potassium chloride and barium hydroxide are mixed.

_____2 KCl + Ba(OH)2  2 KOH + BaCl2 ______

REACTION WRITING PRACTICENAME:

1. Ammonium Dichromate Volcano:

Observations:

Reaction:

Type:

2. Zinc and Sulfur:

Observations:

Reaction:

Type:

3. Aluminum and copper(II) chloride (demonstration)

Observations:

Reaction:

Type:

4. Lead (II) Nitrate and Potassium Iodide: (demonstration)

Observations:

Reaction:

Type:

5. Sodium and chlorine:

Observations:

Reaction:

Type:

6. Hindenburgh Explosion:

Observations:

Reaction:

Type:

7. Thermite

Observations:

Reaction:

Type:

8. Magnesium and carbon dioxide

Observations:

Reaction:

Type:

9. Burning magnesium and water

Observations:

Reaction:

Type: