•IDENTIFY AND BALANCE 5 TYPES OF REACTIONS

•EXPERIMENTALLY DETERMINE INDICATORS OF A REACTION

Unit Five: Chemical Reactions

Chemical Reactions

Process by which the atoms of one or more substances are rearranged to form different substances

Law of Conservation of Matter – Matter is not created or destroyed during a chemical reaction.

Evidence of a Chemical Reaction

1. Formation of a gas Bubbles Smell

2. Formation of a solid (precipitate) from two aqueous solutions; often solids are colorful

“Snow globe” effect “Paint” look “Jello” consistency

3. Change in temperature Test tube feels colder to you (endothermic

reaction) Test tube feels warmer to you (exothermic

reaction)

Writing Chemical Equations

Read a description of the reactionNote what is reacted with whatNote what is yielded or producedWrite formulas for each compoundUse + to represent “and”Use to represent “produces” or

“yields”Include states of matter where available

(s) solid (l) liquid (g) gas (aq) dissolved in water

Balancing Chemical Equations

Write the skeleton equation. BE SURE THE FORMULAS ARE WRITTEN

CORRECTLY.Inventory reactantsInventory productsInsert coefficients to make atoms of

each element equal on both sides of the equation

Reduce the coefficients if possible

Writing & Balancing Equations Handout

1. Zn + Pb(NO3)2 --> Zn(NO3)2 + Pb

2. AlBr3 + Cl2 --> AlCl3 + Br2

Writing & Balancing Equations

1. Zn + Pb(NO3)2 --> Zn(NO3)2 + Pb

2. 2 AlBr3 + 3 Cl2 --> 2 AlCl3 + 3 Br2

3. Na3PO4 + CaCl2 --> Ca3(PO4)2 + NaCl

Writing & Balancing Equations

1. Zn + Pb(NO3)2 --> Zn(NO3)2 + Pb

2. 2 AlBr3 + 3 Cl2 --> 2 AlCl3 + 3 Br2

3. 2 Na3PO4 + 3 CaCl2 --> Ca3(PO4)2 + 6 NaCl

Complete 4, 5, 6, and 8 on your own.

Potassium metal and chlorine gas combine to form potassium

chloride.

Select the balanced chemical equation.A.) K+1 + Cl- --> KCl

B.) K + Cl --> KCl

C.) K + Cl2 --> KCl

D.) 2K + Cl2 --> 2KCl

Aluminum and hydrochloric acid react to form aluminum chloride

and hydrogen gas.Select the balanced chemical

equation.A.) Al+3 + HClO3 --> AlCl + H

B.) Al + 2HClO3 --> AlCl3 + H2

C.) Al + HCl --> AlCl3 + H2

D.) 2Al + 2HCl --> 2AlCl3 + 3H2

E.) 2Al + 6HCl --> 2AlCl3 + 3H2

Calcium hydroxide and phosphoric acid react to form calcium phosphate and water.Select the balanced chemical

equation.A.) CaOH2 + H3P --> Ca3(PO4)2 + H2O

B.) 3CaOH2 + 2H3PO4 --> Ca3(PO4)2 + 6H2O

C.) 3Ca(OH)2 + H32PO4 --> Ca3(PO4)2 + 3H2O

D.) 3Ca(OH)2 + 2H3PO4 --> Ca3(PO4)2 + 6H2O

Hydrogen gas and nitrogen monoxide react to form water

and nitrogen gas.Select the balanced chemical

equation.A.) 2H + NO --> H2O + N

B.) 6H + N2O3 --> 3H2O + 2N

C.) 2H2 + 2NO --> 2H2O + N2

D.) H2 + 2NO --> H2O + N2

Copper and sulfuric acid react to form copper (II) sulfate and water and sulfur

dioxide.

Difficult Equations to Balance

Cu + 2 H2SO4 --> CuSO4 + 2 H2O + SO2

Writing & Balancing Equations

1. Zn + Pb(NO3)2 --> Zn(NO3)2 + Pb

2. 2 AlBr3 + 3 Cl2 --> 2 AlCl3 + 3 Br2

3. 2 Na3PO4 + 3 CaCl2 --> Ca3(PO4)2 + 6 NaCl

4. 2 K + Cl2 --> 2 KCl

5. 2 Al + 6 HCl --> 2 AlCl3 + 3 H2

6. 3 Ca(OH)2 + 2 H3PO4 --> Ca3(PO4)2 + 6 H2O

7. Cu + 2 H2SO4 --> CuSO4 + 2 H2O + SO2

8. 2 H2 + 2 NO --> 2 H2O + N2

5 Types of Chemical Reactions

SynthesisCombustionDecompositionDouble-ReplacementSingle-Replacement

Five Types of Reactions Clip

Synthesis Reactions

A + B --> AB2 or more compounds or elements go

together to build a more complex compound

Synthesis Reaction Clip

Write the balanced chemical equation for the reaction shown in the video clip.

2Al + 3Br2 2AlBr3

Combustion Reactions

Oxygen combines with a substance and releases energy in the form of heat and light

DIATOMIC OXYGEN IS ALWAYS A REACTANT!

Combustion Reaction Clip

In the video, the combustion reaction occurring in the flask used up all of the

oxygen gas in flask. A vacuum formed as a result, and the egg was drawn into the

flask.

Decomposition Reactions

A single compound breaks down into 2 or more elements or new compounds

AB --> A + B

Decomposition Reaction Clip

In the video, hydrogen peroxide is decomposed to form hydrogen gas and oxygen gas. Many

bubbles indicated this gas production. A catalyst of KI was used to speed up the decomposition

reaction.

Double Replacement Reactions

Exchange of ions between 2 ionic compounds

AX + BY AY + BXOften produce a precipitate

Solid, liquid, or gas product formed from two “aqueous” solutions

Aqueous means dissolved in water.Example: Cobalt (II) chloride reacts with

sodium phosphate to produce cobalt (II) phosphate and sodium chloride.

Single Replacement Reactions

One element replaces another element in a compound

A + BX --> AX + BA metal will not always replace another metal.

The reactivity of the metal is important to consider. Only a more active metal replaces a less active metal. A less active metal will not replace a more active metal.

The reaction will simply not occur.Use the metal activity series to determine if

single replacement reactions occur.

Colored Pencil Corrections9-2 Practice Problems (odd)

1. NH3 + HCl NH4Cl

3. BaO + H2O Ba(OH)2

5. Zn + Cu(NO3)2 Zn(NO3)2 + Cu

7. Fe + H2SO4 FeSO4 + H2

9. Co + Cl2 CoCl2

11. N2O5 + H2O 2HNO3

13. C + 2ZnO 2Zn + CO2

15. PCl3 + Cl2 PCl5

17. CaH2 + 2H2O Ca(OH)2 + 2H2

19. C3H8 + 5O2 3CO2 + 4H20

As you come in,

The Materials: Remote control Periodic table Pick up an “Intro to Chemical Reactions Investigations”

handout The Plan:

I-Respond Warm-Up – Types of Reactions Practice Quiz Instructions for “Intro to Chemical Reactions

Investigations” Collaborative investigations in the lab

The Assessments: TOMORROW – Types of Chemical Equations Quiz Thursday – Writing and Balancing Equations Quiz Friday – Predicting Products and Balancing Equations Quiz

A.) Synthesis

B.) Decomposition

C.) Combustion

D.) Single Replacement

E.) Double Replacement

1. When grilling burgers with your friends on Saturday evening, your propane tank and gas grill work together to perform the following reaction:

C3H8 + O2 CO2 + H2O

2. If not stored properly, your hydrogen peroxide can cause a mess in your medicine cabinet. Hydrogen peroxide quickly breaks down in the presence of light to produce oxygen gas and hydrogen gas.

A.) Synthesis

B.) Decomposition

C.) Combustion

D.) Single Replacement

E.) Double Replacement

3. The white precipitate formed by acid rain on a marble statue is produced in the following reaction: CaCO3(aq)+H2SO4(aq)CaSO4(s)+H2CO3(aq)

A.) Synthesis

B.) Decomposition

C.) Combustion

D.) Single Replacement

E.) Double Replacement

9-2 Practice Problems (even)

2. CaCO3 CaO + CO2

4. CH3CHO CH4 + CO

6. CaSO3 CaO + SO2

8. C2H6N2 C2H6 + N2

10.MnI2 Mn + I2

12.2Mg + TiCl4 2MgCl2 + Ti

14.Br2 + 2NaI 2NaBr + I2

16.2P + 3Br2 2PBr3

18.H2SO4 + 2KOH K2SO4 + 2H2O

20. 2C6H6 + 15O2 12CO2 + 6H2O

Predicting Products & States of Matter

52. 2Al + 6HCl 2AlCl3 + 3H2

Predicting Products & States of Matter

52. 2Al(s) + 6HCl(aq) 2AlCl3(aq) + 3H2(g)

56.ZnCl2 + (NH4)2S 2NH4Cl + ZnS

Predicting Products & States of Matter

56.ZnCl2 (aq)+ (NH4)2S(aq) 2NH4Cl(aq) + ZnS(s)

59. HgSO4 + 2NH4NO3 Hg(NO3)2 + (NH4)2SO4

Predicting Products & States of Matter

59. HgSO4(aq) + 2NH4NO3(aq) Hg(NO3)2(aq) + (NH4)2SO4(aq)

60. Fe + CuSO4 FeSO4 + Cu

Predicting Products & States of Matter

60. Fe (s)+ CuSO4 (aq) FeSO4 (aq) + Cu (s)

67. Br2 + 2NaI 2NaBr + I2

Predicting Products & States of Matter

67. Br2 (l) + 2NaI(aq) 2NaBr (aq) + I2 (g)

Colored Pencil Corrections

Al(NO3)3 + NaOH = Al(OH)3 + NaNO3

KClO3 = KCl + O2

H3PO4 + Mg(OH)2 = Mg3(PO4)2 + H2O

NH4NO2 = N2 + H2O

BaCl2 + Na2SO4 = NaCl + BaSO4

Fe2O3 + CO = Fe + CO2

Mg(OH)2 + (NH4)3PO4 = Mg3(PO4)2 + NH3 + H2O

Reactions in Aqueous Solution

More than 70% of earth is covered by water66% of the human body is waterMANY chemical reactions occur in waterOften form solids called precipitates

Remember: Ionic compounds dissociate in water.

Net Ionic Equations

Represent reactions of ionic compounds in aqueous solution by writing complete ionic equations

Remove spectator ions (those appear on both sides of the equation but aren’t in the precipitate)

Leaves a net ionic equation that can be balanced

Chemical Reactions Pre-Lab

Why do I set up the lab with so many aqueous solutions? Rate of Reaction

Temperature – warmer = faster reaction; particles are moving faster

Concentration - # of particles; more particles = faster reaction

State of Matter – dissolved means greater surface area; more surface area = faster reaction

Surface Area - Filings, shot, powder, mossy, etc.; greater surface area = faster reaction

Catalyst – DOES NOT REACT; lowers the activation energy of the reaction