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Name: _________________

Chemical Reactions

Indicators of a chemical change:

1) _______________ change. 3) __________ or _____________ change.

2) A ________ is produced. 4) A solid (____________________) is formed.

5) It ______________ be reversed!!!!

The format of a reaction:

There is a specific format for these types of equations:

The left side of the equation lists the names of all the ___________________.

The right side of the equation lists the names of all the __________________.

An ____________ points from the reactants to the products.

Ex)

____________________: the substances that come in contact BEFORE a chemical reaction can

occur.

____________________: the substances that are FORMED from the chemical change.

If you have more than one reactant or product, they are separated by a __________.

Ex)

There are two main ways in which we can describe chemical reactions:

1) Word Equations: identify the reactants and products in a chemical reaction using only the

_________________ of elements and compounds.

Ex)

2) Chemical Equations: represent the reactants and products in a chemical reaction using their

_______________ or __________________.

These equations follow the same format as above except you write the formula for the

element or compound instead of the word.

Ex) calcium + arsenic calcium arsenide would be written as….

*NOTE: When an element’s name is given, just write the symbol for that element EXCEPT when the following elements are named….

P4 S8 H2 O2 F2 Br2 I2 N2 Cl2

Ex) sodium + chlorine sodium chloride would be written as….

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Practice Chemical Reactions as Equations

1. Use the description of the following chemical reactions to write out a complete word equation: a) Hydrogen and oxygen mix to form water.

b) When aluminum foil is placed in a solution of copper(II)chloride, copper metal and aluminum chloride are formed.

c) When sodium sulfate and calcium chloride solutions are mixed, a precipitate of calcium sulfate and sodium chloride are formed.

2. Convert the following word equations into chemical equations:

a) Calcium chloride + sodium sulfate calcium sulfate + sodium chloride

b) Barium carbonate barium oxide + carbon dioxide

c) Phosphorus + sulfur diphosphorus trisulfide

Conserving Mass in Chemical Reactions

Law of Conservation of Mass: in a chemical reaction, the _________ mass of reactants is

_____________ equal to the __________ mass of the products.

It is also known that matter cannot be ____________________ or _________________. It can only

be changed from one form to another.

What does this mean about matter, specifically atoms, in a chemical reaction?

In a chemical reactions, atoms are ___________ changed.

The mass of the reactants and products is _______________ _______________ because the

___________________ and type of atoms in the reactants and products is equal.

In a chemical reaction, the atoms are simply _____________________. Molecules may be

broken apart and new ones may form, but the atoms in the reactants are the __________

atoms in the products.

Lab: Measuring Mass in Chemical Changes

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H White

C Black

N Blue

Na Green

Balance Equations using Models

How to Make Atoms Equal in a Chemical Reaction

Balancing Equations: Step 1: Write the proper ______________ for each element and compound in the reaction.

Step 2: ____________ each type of atom on the reactant side and on the product side. If you need

to, use a chart.

Step 3: Multiply each formula using a _______________ (large number ____ __________ of the

formula) until both sides of the equation are equal.

When no coefficient is written, assume _____.

DO NOT balance by changing the formula!!!!!

Step 4: Re-count to make sure everything is balanced.

Step 5: ______________ all coefficients if possible.

HINTS:

Balance polyatomics as a group IF they occur on both sides of the equation.

Balance compounds __________ and elements ___________.

How to Count Atoms Review:

1. The symbol of an element represents 1 atom. e.g. Ca = 2. A subscript is used to indicate the number of atoms. e.g. N2 = 3. A subscript outside a bracket multiplies all the elements inside the brackets. e.g. Ba3(PO4)2 =

Make the following Equations on your desk using the above colors

Balanced Equation

H2 + O2 H2O

___ H2 + ___ O2 ___ H2O

H2O2 H20 + O2

___ H2O2 ___ H2O + ___ O2

Na + O2 Na2O

___ Na + ___ O2 ___ Na2O

N2 + H2 NH3

___ N2 + ___ H2 ___ NH3

C + H2 CH4

___ C + ___ H2 ___ CH4

CH4 + O2 CO2 + H2O

____ CH4 + ____ O2 ____ CO2 + ____ H2O

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4. a) A coefficient written in front of a symbol and indicates the number of atoms of that element. e.g. 3 C = b) A coefficient in front of a formula indicates the number of molecules of that compound. NOTE: a coefficient multiplies the number of atoms of each element in the formula. e.g. 2 H2O= 3 FeSO4 = 4 Cu(NO3)2 =

Practice Counting Atoms: Na2CO3 Ca3(PO4)2 K2CrO4 3 BaCl2

NH4C2H3O2 4 Al2(CO3)3 Pb(NO3)2 2 (NH4)2Cr2O7

Practice Balancing Questions with a Chart

1. Ca + O2 CaO

2. N2 + H2 NH3

3. Cu2O + C Cu + CO2

4. C2H6 + O2 CO2 + H2O

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5. Fe2(SO4)3 + AgNO3 Ag2SO4 + Fe(NO3)3

6. Al(OH)3 + HCl AlCl3 + H2O

Worksheet: Balancing Chemical Equations

The 5 Types of Chemical Reactions

Chemists classify reactions to make them easier to predict the products of reactions and recognize

new reactions. There are 5 types of reactions:

1. Synthesis Reaction:

Also called combination reactions

Involves the combination of smaller atoms and/or molecules into larger molecules. (often 2 _____________________ combining to make a _______________________)

The general formula is: A + B AB

Ex.

2. Decomposition Reaction:

Involves the ___________________ of a large molecule into elements or smaller molecules

The general formula is: AB A + B

Ex.

3. Single Replacement Reaction:

Involves an _______________________ and a ________________________ as reactants

One element displaces (replaces) another element from a compound (usually a metal replaces the other ___________________ or the non-metal replaces the other _______________________)

The general formula is: A + BC AC + B or D + EF ED + F (metal replacement) (halogen replacement)

Ex. Ex.

4. Double Replacement Reaction:

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Occurs when elements in different _____________________ displace each other or exchange places.

The general formula is: AB + CD AD + CB

Ex.

5. Combustion Reaction :

Is the ________________________ of something

_______________________ is always a reactant.

If there is combustion of a hydrocarbon (a compound with ______’s and ______’s), the products are ALWAYS ______________________________ and ______________________.

The general formula is: C?H? + O2 CO2 + H2O

Ex. There are TWO types of combustion reactions:

1. Complete Combustion Very rapid reaction of a substance with oxygen to produce compounds called

oxides. AKA burning. Fuel + Oxygen Carbon dioxide + Water and Energy (heat/light)

Most common fuels are hydrocarbons (gas, candles, etc) These fuels produce carbon dioxide + water + energy

Hydrocarbon + Oxygen Carbon dioxide + Water + energy

2. Incomplete Combustion Occurs when there is not enough oxygen available Four products result

1. CO 2. C 3. CO2 4. H2O

Classifying the 5 types of Reactions

1. Classify each of the following reactions as either a synthesis reaction or a decomposition reaction then BALANCE the equation.

a) Fe + O2 Fe2O3 synthesis OR decomposition

b) NaI Na + I2 synthesis OR decomposition

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c) H2 + O2 H2O synthesis OR decomposition

d) ZnCl2 Zn + Cl2 synthesis OR decomposition

2. Classify each of the following reactions as either single replacement (SR) or double replacement (DR) reactions then BALANCE the equation.

a) Cu + AgNO3 Cu(NO3)2 + Ag SR OR DR

b) Zn + HCl H2 + ZnCl2 SR OR DR

c) CaCO3 + HCl H2CO3 + CaCl2 SR OR DR

d) Al + CuCl2 Cu + AlCl3 SR OR DR

3. Balance the following hydrocarbon combustion reactions.

a) ___ CH4 + ____ O2 ____ CO2 + ____ H2O c) ___ C4H8 + ____ O2 ____ CO2 + ____ H2O

b) ___ C4H10 + ____ O2 ____ CO2 + ____ H2O d) ___ C2H6 + ____ O2 ____ CO2 + ____ H2O

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4. Identify the following MIXED reactions. (SYN, DEC, COMB, SR, DR)

a) Zn + Cl2 ZnCl2 SYN DEC COMB SR DR

b) Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag SYN DEC COMB SR DR

c) CaCl2 + Na2SO4 CaSO4 + 2 NaCl SYN DEC COMB SR DR

d) Pb + 4 HCl PbCl4 + 2 H2 SYN DEC COMB SR DR

e) 3Mg + N2 Mg3N2 SYN DEC COMB SR DR

f) 2 C2H6 + 7 O2 4 CO2 + 6 H2O SYN DEC COMB SR DR

Worksheet: Five Types of Reactions

Lab: Five Types of Reactions

Lab: Factors that Affect the Rate of a Reaction

Kinetic Molecular Theory

The energy of motion is called __________________ energy.

Molecules are _______________ in motion. Therefore, all molecules have kinetic energy.

The Collision Model of Chemical Reactions

The collision theory states that in order for a chemical reaction to take place: • Moving particles must ________________ with each other. • Particles must collide with the right ______________________ (line up

correctly). • Particles must collide hard enough/with the right amount of __________________.

Two Ways to Make Reactions Occur More Quickly

1) Increase the ___________________ of collisions. 2) Increase the amount of collisions that are ______________________.

How do we do this? 1) Increase the _________________________________.

By chopping the wood into smaller pieces we have ___________________ the surface area that can be exposed to the flame.

With an increase in the surface area there is an __________________ chance that reactants in a chemical reaction will come in contact with each other.

Therefore, increasing surface area will __________________ the rate of a reaction.

2) Increase the _________________________ of the reactants.

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When you increase temperature, you increase the _______________ (moving) energy of the molecules.

When molecules move about more quickly the ______________ of them colliding and the ___________ with which they collide increases.

Therefore, increasing temperature, ______________________ the rate of a reaction. 3) Increase the _________________________ of the reactants.

Concentrated solutions contain ________ atoms (molecules) than dilute solutions.

If a solution contains a lot more atoms (molecules) the _________________ of a collision occurring increases.

Therefore, increasing concentration, _______________________ the rate of a reaction.

4) Adding a _______________________.

A catalyst is a substance that increases the rate of a chemical reaction without being ___________________ by the reaction.

A catalyst is NOT a reactant. It just helps the reaction go faster by lining up the reactants together and gives them the correct _____________________. It give the reactants an ___________________ pathway to react.

Exothermic and Endothermic Reactions a) Exothermic Reactions: Chemical Changes that release heat/energy into surroundings

b) Endothermic Reactions: Reactions that absorb heat/energy from the surroundings

Classify each of the following processes as exothermic or endothermic:

Acids and Bases Chemists classify matter according to various criteria. One method of classification uses the properties of substances when __________________________________ and results in the categorization of substances as acids or bases.

Acids Bases

* * * * * *

* * * * * *

Both acids and bases have one important common property: they each cause certain dyes to change colour. These dyes are called __________________ and three of the more common dyes are listed below.

Feels hot OR cold Exothermic OR Endothermic

KCl hot OR cold Exothermic OR Endothermic

CaCl2 hot OR cold Exothermic OR Endothermic

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Indicator In acids In bases

Litmus

Bromthymol Blue

Phenolpthalein

Formulas for Acids and Bases Common acids are easily recognized because their formulas begin with a hydrogen, H. ex) HCl, H2SO4, H3PO4. Most bases are compounds that contain the hydroxide ion, OH-. ex) NaOH, Ca(OH)2, Al(OH)3.

Practice: Acid or Base?

Formula Acid or Base? Name of Compound

HCl Acid or Base

KOH Acid or Base

Mg(OH)2 Acid or Base

HNO3 Acid or Base

H2SO4 Acid or Base

The pH Scale Chemists use the pH scale to represent how ___________ or _________ a solution is. A very acidic solution has a very _________ pH value. A neutral solution has a pH of _____. A very basic (or alkaline) solution has a very ________ pH value.

pH: A Logarithmic Scale The pH scale is logarithmic, which means that every change of one unit on the scale is a ___________ effect on the concentration of the solution. ex) A substance with a pH of 2 is ________ times more acidic than something with a pH of 3 and __________ times more acidic than a pH of 4!

Reacting Acids With Bases When acids and bases mix together, a __________________________ reaction occurs. The products are a ________________ (ionic compound) and _____________________. The resulting solution is ________________________ (no charge). ex) acid + base a salt + water ex) HBr + NaOH _____________ + ___________________ *This is just a _____________________________________ reaction of an acid and a base.

Practice: Neutralization Reactions Complete and balance the following neutralization reactions:

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1) HCl + Al(OH)3 2) H2S + NaOH 3) H3N + Ca(OH)2 4) HF + KOH 5) H2SO4 + LiOH

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