Bonds Formulas & Reactions

Chemical
Reactions and
Equations Physical
Science

Tierheim Associates

PSCI.PS1.11 USE MODELS TO IDENTIFY CHEMICAL REACTIONS AS SYNTHESIS,

DECOMPOSITION, SINGLE-REPLACEMENT, AND DOUBLE-REPLACEMENT. GIVEN THE
REACTANTS, USE THESE MODELS TO PREDICT THE PRODUCTS OF THOSE CHEMICAL

REACTIONS.

Develop and use models to
identify the five basic types
of reactions: synthesis,
decomposition (analysis),
single replacement, double
replacement, and
combustion

01

Use models of chemical
reactions to identify the
coefficient to balance a
chemical reaction.

02

Use models of chemical
reactions to identify and
help predict the products
for any given chemical
reaction.

03

How do we measure the amount of a substances?

•Moles

• 1 mole = 6.022 x 1023 representative particles
• The molar mass is the mass of one mole of a sample. To find the

molar mass, add the atomic masses (atomic weights) of all of
the atoms in the molecule.

•Grams

Note 1mL water = 1 gm so 1000 mL or a 1 L bottle is about 1Kg
•Milliliters 1 cubic centimeter 1 L = 1dm3

Chemical

Reactions and

Chemical
Equations

•Chemical reactions occur when
one or more substances (atoms,
elements, or compounds)
interact or undergo a change to
produce a new substance.
•The chemical equation will
describe the chemical reaction.

NaOH+HCl NaCl+H2O

Chemical Reactions

•All the following involve
Chemical reactions

• Baking foods
• Digestion
• Making plastics
• Running your car

releasing the energy in
the fuel

Detecting
Chemical
Reactions

• Chemical Reactions often cause a change in

color.

• Chemical Reactions may release gases or

bubble.

• Chemical Reactions may give off heat and/or

light. (EXOTHERMIC)

• Chemical Reaction may absorb heat.

(ENDOTHERMIC)

• Chemical Reactions may form PRECIPITATES

(insoluble substances)

Dropdown

A chemical reaction that gives off heat or light is called a(n) ​

Select answer

reaction.

Multiple Choice

Which of the following would be an exothermic reaction?

• burning a log

• baking a cake

• using a cool pack

• freezing water

Dropdown

A chemical reaction that absorbs heat is called a(n) ​

Select answer

reaction.

Chemical
Equations

• Chemical equations are shorthand

notations of chemical reactions.

• All reactants & products must be

represented.

• Correct formulas must be used

• The law of conservation of mass must be

observed by using proper coefficients to
balance molar quantities of substances

Reactants and Products

•Reactants are the materials that are
present at the beginning of a chemical
reaction.
•Products are the materials that are
produced at the end of the chemical
reaction.

Reactants and Products

• The starting materials are known as the reactants, they

react.

• The new substance (s) that result from the reaction are

known as products.

• Matter cannot be created or destroyed so...

• The mass of the reactants must equal the mass of the

products.

Dropdown

Substances to the left of the arrow that are present at the beginning of the chemical reaction are called:​

Select answer

​

Dropdown

Substances to the right of the arrow that are present at the end of the reaction are called ​

Select answer

Section 2: Chemical

reactions are represented

by balanced chemical

equations.

Section 1: There are four

types of chemical reactions:

synthesis, combustion,

decomposition, and replace

replacement reactions.

Section 3:

Double-replacement reactions
occur between substances in
aqueous solutions and produce
precipitates, water, or gases.

General
Chemical
Equation

Chemical

equations are

shorthand forms

of writing out

chemical
reactions.

They use symbols and
coefficients to describe

the elements and

compounds that react
and how much of each

substance reacts.

Word Equations

• In word equations, the reactants and products are written out: sodium

hydroxide and hydrochloric acid react to yield sodium chloride and water

• The words only describe the reaction and are qualitative not quantitative.

(they DO NOT tell how much of each substance is used or produced)

• sodium hydroxide + hydrochloric => sodium chloride + water

• The arrow is read yields, produces, or forms

NaOH + HCl NaCl + H2O

reactants products

Formula Equations

Formula equations should represent the reactants and products
with symbols and formulas, the physical state of the substance, as
well as the quantities of the reactants and products.

2HCl(aq) +Zn(s) => ZnCl2(aq) + H2(g)

Arrows are sometimes used to indicate gases
and precipitates .

Key Equation Components

​In a chemical equation, the reactants are written on the left, and the products are written on the right.​

The coefficients next to the symbols of entities indicate the number of moles of a substance produced or used in the chemical reaction.​

The reactants and products are separated by an arrow, usually read aloud as “yields.”​

Chemical equations should contain information about the state properties of products and reactants, whether aqueous (dissolved in water — aq), solid (s), liquid (l), or gas (g).​ ​

​Balanced Chemical Equation

​Write the proper chemical formulas for the reactants and products.​

• Make a chart of the atoms in the equation.​

• Count the number of each atom in the reactants and compare it to the number of the same type of atoms in the products.​

• If all atoms are the same in the reactants and products then the equation is balanced.​

• If an atom is not equal on both sides a COEFFICIENT must be added in front of the compound to balance the number of atoms.​

• Recalculate the number of each atom.​

• Repeat steps 4 through 6 as many times as necessary until all atoms are balanced.​

• Check your equation to be sure you made no errors and that it is in the lowest possible terms.​

Essential Questions
• What is evidence of chemical

change?

• How are chemical reactions

represented?

• Why do chemical equations

need to be balanced and how
is this accomplished?

• How are chemical reactions

classified?

• What are the characteristics

of different classes of
chemical reactions?

Drag and Drop

Which of the following are evidence of a chemical reaction? ​

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​ ​

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Drag these tiles and drop them in the correct blank above

change of Color

change of temperature

precipitation

release of gas or odor

release of light

change of phase/state

separation of substances

boiling

sublimation

deposition

Dropdown

Insoluble​ substances that form during a chemical reaction are called ​

Select answer

Dropdown

A(n) ​

Select answer

is a substance that speeds up a chemical reaction rate.

Dropdown

Numbers that precede the symbols and formulas in chemical reactions are called​

Select answer

.

CLASSIFYING AND

PREDICTING CHEMICAL

REACTIONS

Vocabulary

New

synthesis reaction

combustion reaction

decomposition reaction

single-replacement reaction

double-replacement reaction

precipitate

COMPOSITION OR SYNTHESIS
REACTIONS

▪ Composition reactions are chemical reactions

in which two or more substances combine to
form a new substance.

Egg + Milk + butter + sugar + Flour + … => CAKE

Bake 3500

▪ Chemists classify reactions

in order to organize the many
types.

▪ A synthesis reaction is a

reaction in which two or
more substances react to
produce a single product.

▪ When two elements react,

the reaction is always a
synthesis reaction.

Types of Chemical
Reactions—Synthesis
Reactions

▪ A decomposition reaction is

one in which a single
compound breaks down into
two or more elements or
new compounds.

▪ Decomposition reactions

often require an energy
source, such as heat, light,
or electricity, to occur.

Decomposition
Reactions

DECOMPOSITION
REACTIONS

▪ A compound is broken down

into two or more different
substances in a
decomposition reaction.

▪ We break down simple sugars

into carbon dioxide and water
during cellular respiration.

▪ Decomposition reactions such

as the reaction above are
known as COMBUSTION
REACTIONS if they occur in
the presence of oxygen.

ELECTROLYSIS
AND
COMBUSTION

▪Decomposition by
using an electric
current is known as
electrolysis.

▪Decomposition in the
presence of oxygen is
known as
combustion.

DECOMPOSITION

GIPHY.GIF (480×210) NOT FOR COMMERCIAL
USE

▪Glucose breaking down to
carbon dioxide and water
is decomposition.

▪Fuel burning is
combustion

▪C2H6

+ O2🡺 =CO2 + H2O

COMBUSTION
REACTIONS

▪ In a combustion reaction,

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

▪ Heated hydrogen reacts

with oxygen to produce heat
and water in a combustion
reaction, seen below. This is
also a synthesis reaction.

METALS & DECOMPOSITIONS

Metal oxides decompose when heated to
form metals and oxygen gas.

▪HgO(s) 🡺 Hg + O2
Metal carbonates decompose when heated
to form metal oxides & carbon dioxide

▪CaCO3 🡺 CaO + CO2
Metal Chlorates decompose when heated
to form metal chlorides and oxygen.

▪KClO3🡺 KCl + O2

ACID DECOMPOSITION

Acids often decompose to form water.

▪H2SO4🡺 SO3 + H2O

Neutralization

▪Acid and base make salt and water

▪NaOH + HCl 🡺 NaCl + H2O

Multiple Choice

Copper and sulfur can react to form two different products: Copper (I) and Sulfur will form __________; Copper (II) and Sulfur will form __________

• Cu₂S ; CuS

• Cu₂SO₄; CuS

• CuS; Cu2S

• Cu2SO4; CuSO4

Multiple Choice

Complete the following decomposition reaction: 2HBr ==> _____ + Br₂.

• 2H

• H₂

• H₂O

Multiple Choice

The decomposition of substances such as pentane fuel in the presence of oxygen releases CO2 and H2O. The type of decomposition is known as ______

• neutralization

• respiration

• combustion

• combination

REPLACEMENT REACTIONS

Single Replacement: you want to make butterscotch chip

cookies but only see chocolate chips. You find Butterscotch
chips and put the chocolate chips down and buy the
butterscotch chips.

Double Replacement: You like chocolate chip cookies but have

brownies. Your friend likes brownies but has chocolate chip
cookies. You trade desserts.

REPLACEMENT
REACTIONS

▪A reaction in which the
atoms of one element
replace the atoms of
another element in a
compound is called a
single replacement
reaction.

▪A + BX → AX + B

REPLACEMENT
REACTIONS

▪A metal will not always replace a
metal in a compound dissolved in
water because of differing
reactivities.

▪An activity series can be used to
predict if reactions will occur.

▪Halogens frequently replace other
halogens in replacement reactions.

▪Halogens also have different
reactivities and do not always replace
each other.

SINGLE

REPLACEMENT

REACTIONS

▪One element replaces another
element in a compound during a
single replacement reaction.

▪Copper replaces silver in silver
nitrate to form copper nitrate
and release silver.

DOUBLE REPLACEMENT

REACTIONS

In a double replacement
reaction, the ions switch
places to form two new
compounds.

Silver exchanges place
with sodium in a reaction
between silver nitrate and
sodium chloride. Silver
chloride and sodium
nitrate are formed.

HOW ARE CHEMICAL EQUATIONS

BALANCED TO SATISFY THE LAW OF

CONSERVATION OF MATTER?

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Multiple Choice

Reactions between acids and bases are a type of ______________ reaction called a neutralization reaction.

• synthesis

• single replacement

• double replacement

• decomposition

Multiple Select

Predict the products: Ca(OH) + 2HCl ==> ______ + _______

• CaCl₂

• H₂O

• CaClO

• H₂

Match

Match the following reaction types and descriptions

• The reaction of a substance with oxygen to produce heat

• One element displaces another element in a chemical compound during a chemical reaction

• Breaking down a substance into 2 or more simpler substances

• Two or more substances combine to form a new substance

• The ions in compounds switch places forming 2 new substances

combustion

single displacement

decomposition

synthesis

double replacement

• combustion

• single displacement

• decomposition

• synthesis

• double replacement

Match

Match the following equations with the reaction type

• Decomposition

• Single Replacement

• Synthesis

• Double Replacement

KClO3 => KCl + O2

Zn + FeCl3 => Fe + Cl2

Mg + O2 => MgO

AgNO3 + ZnCl2 => AgCl + Zn(NO3)

• KClO3 => KCl + O2

• Zn + FeCl3 => Fe + Cl2

• Mg + O2 => MgO

• AgNO3 + ZnCl2 => AgCl + Zn(NO3)

ACTIVITY SERIES

▪Tables of the ACTIVITY
SERIES show which
reactants will replace each
other.

▪Any element in the series can
replace elements below it.

AB + CD > AD + CB Double replacement reactions generally involve two compounds, each contributing a cation (+) and anion (-) to the reaction.

 The cations exchange anions, with no change in oxidation number.

 Precipitation Reactions involve formation of an insoluble product as the driving force

​Double Replacement Reactions

Oxidation/Reduction

​•After a chemical reaction, elements gain, lose, and share electrons differently than before the reaction.  This exchanging of electrons allows bonds to break and forms new bonds, changing the OXIDATION NUMBER of the elements.

Oxidation /Reduction

​ 0 0 +1 -1

2Na + Cl₂ ==> 2NaCl

•Elements that lose electrons during a chemical reaction are oxidized:  2Na + Cl 2 ==> 2NaCl   Na is a neutral metal that loses electrons when bonding.

•Elements that gain electrons during chemical reaction are reduced:  Cl gas is a neutral gas that gains electrons during bonding to form chlorine ions.

•

Multiple Choice

Study the equation below and indicate which element is oxidized. 2Na + 2H₂O ==> 2NaOH + H₂

• Na

• H

• O

• None, all have the same charge as reactants and products.

Multiple Choice

Study the equation below and indicate which element is reduced. 2Na + 2H₂O ==> 2NaOH + H₂

• Na

• H

• O

• None, all have the same charge as reactants and products.

PSCI.PS3.9 DEMONSTRATE THE IMPACT OF THE STARTING AMOUNTS OF REACTING SUBSTANCES UPON
THE ENERGY RELEASED.

Reaction Rates

Some happen very quickly like explosions, others happen very slowly like metal rusting.

Reaction rates can be changed by adding a catalyst, changing the energy level, or changing the particle size.

Increasing the concentration or pressure can increase the reaction rate.

PS3.D: ENERGY IN CHEMICAL PROCESSES AND
EVERYDAY LIFE — THE WONDER OF SCIENCE