Chapter 8.1. Warm up 1. What is a chemical reaction? 2. What is conservation of mass? 3. How are the two concepts above related? 4. When heated, solid.

CHEMICAL REACTIONS

Chapter 8.1

Warm up1. What is a chemical reaction? 2. What is conservation of mass? 3. How are the two concepts above related?4. When heated, solid potassium chlorate

decomposes to form solid potassium chloride and oxygen gas. Write the balanced equation. (chlorate = ClO3

-1)

Make sure your warms ups are ready to turn in: dates clear and boxes or highlighted, name on paper

2KClO3(s) → 2KCl(s) + 3O2(g)

Writing Chemical Equations Chemical reactions occur every day.

Digesting photosynthesiscooking

In a chemical reaction, one or more reactants are converted to one or more new products.

Evidence of chemical reactionsHow do you know if a chemical reaction has occurred? Change in energy (gets hot

or cold) Produce a gas (bubbles) Color change Form a precipitate= form

solid from 2 liquids

Symbols to knowYield (produces)Reaction in both directions

(s) Solid form

(l) Liquid

(aq) Aqueous= Dissolved in water

(g) gasH2SO4 (aq) H2 (g) + S (s) + O2 (g)

Subscript # = number of atoms of each element

Represent Reactions with chemical equations

Word equationsEx: Iron reacts with oxygen gas to produce iron (III) oxide. Iron + oxygen gas iron (III) oxideHow many reactants and products in the following? 1. Hydrogen peroxide decomposes to

produce water and oxygen gasHydrogen peroxide water + oxygen

2. Methane and oxygen gas react to produce carbon dioxide and water

Methane + oxygen carbon dioxide + water

Chemical Equation Chemical equations replace words with

formulas. Skeleton chemical equations do NOT

show the relative abundance of each chemical. THEY ARE UNBALANCED.Ex: Oxygen and hydrogen combine to form water

O2 (g) + H2(g) H2O(l)

Write the skeleton chemical equations

1. Solid Iron reacts with oxygen gas to produce iron (III) oxide (rust).

2. Aqueous Hydrogen peroxide (H2O2) decomposes to produce water and oxygen gas.

3. Solid sulfur burns in the presence of oxygen gas to form sulfur dioxide gas.

Fe(s) + O2(g) → Fe2O3(s)

H2O2(aq) → H2O (l)+ O2(g)

S(s) + O2(g) → SO2(g)

Balancing Chemical Equations

Subscripts—used in formulasCoefficients—before the symbol, used to balance equations

Solid sulfur burns in the presence of oxygen to form sulfur dioxide gas.

Iron reacts with oxygen gas to produce iron (III) oxide.

YOU CANNOT CHANGE SUBSCRIPTS TO BALANCE!!!

S(s) + O2 (g) SO2(g)

Fe(s) + O2(g) → Fe2O3(s)4Fe(s) + 3O2(g) → 2Fe2O3(s)

H2 (g) + O2 (g) H2O (l)

Write the Coefficient to Balance- balance the more complicated molecule first, then single molecules

1. ___H2 (g) + ___O2 (g) ___H2O (l)

2. ___Ag2S (s) + ___Al(s) ___Ag(s) + ___Al2S3 (s)

3. ____AgNO3 + ____H2S ___Ag2S + ____HNO3

4. When heated, solid potassium chlorate decomposes to form solid potassium chloride and oxygen gas.

2KClO3(s) → 2KCl(s) + 3O2(g)

2 2

Why Balance?? Law of conservation of mass says so…

Law of Conservation of Mass: - Total mass of the universe is constant- Mass can not be created or destroyed- In a closed system, mass can not

change quantity (though it can change form)

Balancing Equations- put in classwork section of

notebook

1. __Li(s) + __Cl2(g) → __LiCl(s)

2. __Fe(s) + __O2(g) → __Fe2O3(s)

3. __H2O2 → __H2O + O2

4. __KClO3(s) → __KCl(s) + __O2(g)

5. __P4(s) + __Cl2(g) → __PCl3(l)

Write the balanced equation by filling in the coefficients. If the coefficient is 1, you don’t write anything

6. Aluminum metal reacts with oxygen gas to produce aluminum oxide solid.

7. Gaseous nitrogen dioxide decomposes to form dinitrogen tetroxide gas.

8. Solid diboron trioxide reacts with water to form boric acid (H3BO3) in aqueous solution. Advanced problems:

9. __NH3 + __O2 __NO + __H2O10. __C2H6 + __O2 __H2O + __CO

Balancing Equations- put in classwork section of

notebook

Bozeman chemical bonding

https://www.youtube.com/watch?v=_B735turDoM

Answers1. 2Li(s) + Cl2(g) → 2LiCl(s)

2. 4Fe(s) + 3O2(g) → 2Fe2O3(s)

3. 2H2O2 → 2H2O + O2

4. 2KClO3(s) → 2KCl(s) + 3O2(g)

5. P4(s) + 6Cl2(g) → 4PCl3(l)

6. Aluminum metal reacts with oxygen gas to produce aluminum oxide solid. 4Al(s) + 3O2(g) → 2Al2O3(s)

7. Gaseous nitrogen dioxide decomposes to form dinitrogen tetroxide gas. 2NO2(g) → N2O4(g)

8. Solid diboron trioxide reacts with water to form boric acid (H3BO3) in aqueous solution. B2O3(s) + 3H2O(l) → 2H3BO3(aq)

9. 4NH3 + 5O2 4NO + 6H2O

10. 2C2H6 + 5O2 6H2O + 4CO

3. Aqueous Hydrogen peroxide decomposes to produce water and oxygen gas.

    4. Solid sulfur burns in the presence of oxygen to form

sulfur dioxide gas.     5. Write the balanced synthesis reaction showing the

production of Magnesium nitride from its elements.     6. Solid Iron (III) sulfide is produced from its solid

elements. Write the balanced equation for this reaction.

lab

2 AgNO3 (sol) + CuCl2 (sol) --> Cu(NO3)2 (sol) + 2 AgCl (ppt)

We will change seats, but not today.Start a new warm up paper:

1/6/15

NamePer, RowWarm-ups #1

1. 2.

_/__/15

1. What did you do well in Chemistry class last semester?

2. What was something that was hard for you?

3. Set one goal for yourself for this semester in chemistry class.

Read the article “peeing in the pool…”4. How does your chemistry knowledge help you understand this article?5. What elements do you think make up cyanogen chloride? Thrichloramine?

Warm up

1. What did you do well in Chemistry class last semester?

2. What was something that was hard for you?

3. Set one goal for yourself for this semester in chemistry class.

Reminders/ thing to do

Grades from last semester are final, you are starting with a clean slate!

Need a notebook, red pen, and calculator Can continue using the same notebook,

if you have enough room (this is recommended)

Clean out your binder/ backpack! (store stuff at home if you want)

Keep your final study guide! Use it to reference material you might

forget!

After correcting test:

Title a paper: “Ch 8.1 bookwork”

Read ch 8.1 pg 260-275Answer: Pg. 274 “practice” 1. a-c and Section Review # 1-2, 4-5And pg 275 #1-2

Warm up Lab Safety Review 1. What is the most important rule in

the lab?2. When using a Bunsen burner, what

important safety precautions do you need to take? (min of 3)

3. What can you do to avoid skin contact with any chemicals?

4. If you do accidently get a chemical on you, what should you do?

Semester 2

Ch 8: Chemical Reactions

ClIF H BrONDiatomic Elements: mnemonic devise

Cl2, I2, F2, H2, Br2, O2, N2

5 Types of Chemical Reactions

1. Synthesis2. Decomposition3. Single Replacement 4. Double Replacement 5. Combustion

+ +

+

Synthesis!

1. Synthesis

2 or more substances combine into one single product

Examples: Mg (s) + O2 (g) MgO (s)

K + Cl2 KCl Cu + S CuS

Ex: Write the balanced synthesis reaction showing the production of Magnesium nitride from its elements.Ex: Solid Iron (III) sulfide is produced from its solid elements. Write the balanced equation for this reaction

+

++

Decomposition!

2. Decomposition The break down of a single substance into 2 or

more products Examples

HgO (s) Hg (l) + O2 (g)

H2SO4 (aq) H2 (g) + S (s) + O2 (g)

HI H2 + I2 Ex: Write the formula showing the

decomposition of hydrobromic acid (HBr) into the diatomics hydrogen gas and bromine liquid

Ex: When electricity is applied water as a catalyst, it forces the decomposition of it into diatomic gases of hydrogen and oxygen. Write the balanced equation for this reaction

https://www.youtube.com/watch?v=mamoT11TEV4

+

+

Single Replacement!

3. Single Replacement One element replaces a 2nd in a

compound. Metals displace metals, non-metals

displace non-metals Hydrogen is the exception (acts like a metal)

Examples Zn + Cu(NO3)2 Cu + Zn(NO3)2

Br2 + NaI I2 + NaBr

Zn + H2SO4

H2 + ZnSO4

Would the following reaction occur??

CaCl2 + Na NaCl + Ca Will Na displace Ca???

Why? Why not?

Activity Series: show how reactive an element is.

Pg 286 -a more reactive element will replace a less reactive element

Will it react? If so, what is the product?

1. Zn + H2O(l)

2. Sn + O2

3. Cd + Pb(NO3)2

4. Cu + HCl 5. Will solid iron and Lead

(II) nitrate react in a single replacement reaction? If so, write the balanced chemical formula for this reaction.

Cd(NO3)2 + Pb

SnO or SnO2

No reaction

No reaction

4. Double Replacement 2 elements (metals/+ ions) switch

partners. Examples

Na2S + Cd(NO3)2 CdS + NaNO3

NaCN + H2SO4

Ca(OH)2 + HCl HOH + CaCl2 HOH = Water

+- +

https://www.youtube.com/watch?v=opY3FLrPTa4

HCN + Na2SO4

+

+

Double Replacement

Synthesis

Decomposition

Single replacement

Double replacement

Write and Balance

1. In a double replacement reaction sodium hydroxide (NaOH) and iron (III) nitrate react. Write the balanced formula for this reaction. 

2. Aqueous barium nitrate and aqueous phosphoric acid (H3PO4) react to produce barium phosphate precipitate and aqueous nitric acid (HNO3).

5. Combustion Reaction

When a compound or element is burned (in the presence of oxygen)

Energy in the form of heat and light is produced

Hydrocarbons are often the other reactant. Complete combustion products are

always CO2 and H2O Incomplete combustion products are

typically C (soot), CO gas and H2Ohttps://www.youtube.com/watch?v=UygUcMkRy_c

Examples of Combustion Rxns C6H6 + O2 CO2 + H2O (benzene)

CH4 + O2 CO2 + H2O (methane)

Ex: Write a balanced equation for the complete combustion of glucose (C6H12O6).

1. 2SO2 + O2 2SO3

2. Al2(SO4)3 + 3Ca(OH)2 2Al(OH)3 + 3CaSO4

3. 2C2H2 + 5O2 4CO2 + 2H2O

4. Mg + 2AgNO3 Mg(NO3)2 + 2Ag

5. 3Ba(NO3)2 + 2H3PO4 Ba3(PO4)2 + 6HNO3

6. Mg(ClO3)2 MgCl2 + 3O2

7. 2Be + O2 2BeO

8. 2Al + 3CuSO4 Al2(SO4)3 + 3Cu

9. 2PbO2 2PbO + O2

10.2C2H6 + 7O2 4CO2 + 6H2O

What type of chemical reaction is each of the following?

1. 2SO2 + O2 2SO3

2. Al2(SO4)3 + 3Ca(OH)2 2Al(OH)3 + 3CaSO4

3. 2C2H2 + 5O2 4CO2 + 2H2O

4. Mg + 2AgNO3 Mg(NO3)2 + 2Ag

5. 3Ba(NO3)2 + 2H3PO4 Ba3(PO4)2 + 6HNO3

6. Mg(ClO3)2 MgCl2 + 3O2

7. 2Be + O2 2BeO

8. 2Al + 3CuSO4 Al2(SO4)3 + 3Cu

9. 2PbO2 2PbO + O2

10.2C2H6 + 7O2 4CO2 + 6H2O

1. S2. DR3. C4. SR5. DR6. D7. S8. SR9. D10.C

What type of chemical reaction is each of the following?

Ch 8.2-8.3 HW

Ch 8.2 pg 284 #1-4 Ch8.3 pg 287 #1-4

https://www.youtube.com/watch?v=FofPjj7v414

Complete the reaction… Pb(OH)4 + NaCl

ppt??? Pb + NaCl Are you sure about that answer??? AgNO3 + MgCl2

ppt? KOH

Complete the reaction

AgCl + Zn Did I catch you again? Al2(SO4)3 + Ca Ba(NO3)2 + Cd3(PO4)2

ppt? Na + O2 CH4 + O2 Say the word equations…

Go to www.creative-chemistry.org.uk/gcse/revision/equations/03.htm

You will complete at least 20 problems.

Sulfuric acid and powdered sugar https://www.youtube.com/watch?v=

ed2AbvQ6ZrQ

Bozeman: https://www.youtube.com/watch?v=

yS8noHTIJ_E

Predicting Precipitates

Precipitate: Liquid + Liquid = Solid Cloudy Solubility determines formation Solubility chart

Soluble means NO precipitate will form!

Will a precipitate form?? Write the products first to determine.

Na2 CO3 + Ba (NO3)2

H2SO4 + Pb(OH)2