Chapter 10 Chemical Reactions 10.1Reactions and EquationsVocabularyReview

_____________________- a process involving one or more substances changing into a new substanceNew

chemical reactionreactantproductchemical equationcoefficient

Main Idea – Chemical reactions are represented by balanced chemical equations.

Chemical Reactions• The process by which one or more substances are rearranged to form different substances is called a

_________________________.• Evidence of a chemical reaction

– Change in___________________• Heat absorbed or produced • _________________________________________

– Change in __________________– _________________ may be produced–– Odor, __________, or bubbles may form.– A solid may form – called a_______________________.

Representing Chemical Reactions• Chemists use statements called _________________ to represent

chemical reactions.• ____________________ are the starting substances.• ____________________ are the substances formed in the reaction.

Reactants → Products

• In a chemical reaction• Atoms aren’t created or destroyed • the __________________________________________ is followed

• A reaction can be described several ways, for example:In a _____________________every item is a word

Copper reacts with chlorine to form copper (II) chloride.

In a ______________________________ some symbols usedCopper + chlorine → copper (II) chloride

In a _______________________________ only symbols usedCu(s) + Cl2(g) → CuCl2(s)

Symbols in equations • the arrow (→) separates the reactants from the products (arrow points to products)

• Read as: ______________ or __________________• The plus sign = “_________”• (s) after the formula = ______________: Fe(s)

• (g) after the formula =______________: CO2(g) • (l) after the formula = ______________: H2O(l)

• (aq) after the formula = __________________ • the substance is _________________ in water: • NaCl(aq) is a salt water solution

_________ double arrow indicates a reversible reaction (more later) _______________________________shows that heat is supplied to the reaction ____________________ is used to indicate a catalyst is supplied

■ (in this case, platinum is the catalyst) – ■ “__________” means any catalyst.

• What is a catalyst?• A substance that______________ up a reaction, without being changed or used up by

the reaction.• _________________ are biological or protein catalysts in your body.• More in a later chapter!

Representing Chemical Reactions In word equations,

aluminum(s) + bromine(l) → aluminum bromide(s) read as :

“aluminum ________ bromine react to _____________ aluminum bromide.”

• ______________________________ use symbols and formulas to represent the reactants and products.Al(s) + Br(l) → AlBr3(s)

• Skeleton equations ___________________________ about how many atoms are involved in the reaction.

• A __________________________________ is a statement that uses chemical formulas to show the identities and relative _______________________ of the substances involved in a chemical reaction.

Example - Write a skeleton equation for:

1. Solid iron (III) sulfide reacts with gaseous hydrogen chloride to form iron (III) chloride and hydrogen sulfide gas.

2. Nitric acid dissolved in water reacts with solid sodium carbonate to form liquid water and carbon dioxide gas and sodium nitrate dissolved in water.

Example - Now, read these equations:

Fe(s) + O2(g) → Fe2O3(s)

Cu(s) + AgNO3(aq) → Ag(s) + Cu(NO3)2(aq)

NO2(g) N2(g) + O2(g)

Balanced Chemical Equations• This figure shows the __________________________

for the reaction between aluminum and bromine.

• Atoms can’t be created or destroyed in an _________________ reaction:• All the atoms we start with we must end up with (meaning: _________________!)

• A balanced equation has the same number of each element on _____________sides of the equation.• A ____________________ in a chemical equation is the number written ________________ of a reactant

or product, describing the lowest whole-number ______________ of the amounts of all the reactants and products.

• The most fundamental law in chemistry is the ______________________________________.• Balanced equations show this law!

Summary of Rules for balancing1) Write a __________________equation if not given it2) Count the number of ________________ of each type appearing on both sides3) Balance the elements one at a time by adding___________________ (the numbers in front) where

you need more - save balancing the _____ and _____until __________! (hint: Save____ until the very last – it will generally balance itself at this point)

4) _____________ to make sure it is balanced.

______________ change a ________________to balance an equation. You can only change coefficients) H2O is a different compound than H2O2

____________ put a coefficient in the _________________of a formula. they must go only in the ___________ ______________ is correct, but Na2Cl is not.

Practice Balancing Examples

___AgNO3 + ___Cu → ___Cu(NO3)2 + ___Ag

___Mg + ___N2 → ___Mg3N2

___P + ___O2 → ___P4O10

___Na + ___H2O → ___H2 + ___NaOH

___CH4 + ___O2 → ___CO2 + ___H2O

10.2 Classifying Chemical ReactionsVocabularyReview

______________ an element that is a solid at room temperature, a good conductor of heat and electricity, and is generally shiny

Newsynthesis reactioncombustion reactiondecomposition reactionsingle-replacement reactiondouble-replacement reactionprecipitate

Main Idea - There are four types of chemical reactions: synthesis, combustion, decomposition, and replacement reactions.

Types of Chemical Reactions• Chemists classify reactions in order to organize the many types.

• There are probably millions of reactions.• Many of them can be classified in 4 or 5 categories

Synthesis Reaction• A synthesis reaction is a reaction in which two or more substances react to produce a _________________

______________________• When ________________________ react, the reaction is always a synthesis reaction.

Combustion Reactions• In a combustion reaction, _________________combines with a substance and releases energy in the form

of ____________________________.• Example - Heated hydrogen reacts with oxygen to produce heat and water in a combustion

reaction. This is also a synthesis reaction.

• Some combustion reactions are synthesis reactions, but not all of them.• For Example,

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

Decomposition Reactions• A decomposition reaction is one in which a single compound ______________________ into two or more

elements or new compounds.________________________

• Decomposition reactions often _________________________________, such as heat, light, or electricity, to occur.

Replacement Reactions• A reaction in which the atoms of one element replace the atoms of another element in a compound is

called a _______________________________.

_______________________• A _____________ will not always replace another metal in a compound dissolved in water because of

____________________________.

• An _________________________ can be used to ______________ if reactions will occur.

• _____________________ frequently replace other halogens in replacement reactions.

• Halogens also have _________________________ and do not always replace each other.

• ___________________________ reactions occur when __________________________ between _________________________.

• This figure shows a generic double replacement equation and a specific example

• The _____________________________ produced during a chemical reaction in a solution is called a __________________________.

• All double replacement reactions produce one of these:

• _______________________

• ________________________

• _______________________

• This table shows the steps to write double replacement reactions.

Predicting Products• This table summarizes different ways to predict the products of a chemical reaction.

10.3 Reactions in Aqueous SolutionsVocabularyReview

__________________: a uniform mixture that might contain solids, liquids, or gasesNew

aqueous solutionsolutesolventcomplete ionic equationspectator ionnet ionic equation

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

• An _______________________ contains one or more dissolved substances (called ____________) in water.• The ____________________ is the most plentiful substance in a solution.• __________________ is always the solvent in an aqueous solution.• There are many possible solutes

• ____________and alcohol are molecular compounds that exist as_________________ in aqueous solutions.

• _______________ are ionic compounds that exist as i____________ in aqueous solutions.• Compounds that produce ______________________ in aqueous solutions are ______________.

• ______________________ (salts) can be solutes in aqueous solutions.• When ionic compounds ________________ in water,

their _________________________ in a process called _______________________.

Types of Reactions in Aqueous Solutions• When two solutions that contain ions as solutes are combined, the ____________________________.• If they react, it is always a ______________________________ reaction.• Three products can form:

• Precipitates• water• gases.

Example - Aqueous solutions of sodium hydroxide and copper(II) chloride react to form the precipitate copper(II) hydroxide.

_______________________________________________________

• Ionic equations that show all of the particles in a solution as they actually exist are called ______________________________________________.

_______________________________________________________________________

• Ions that do not participate in a reaction are called ___________________________ and are not usually written in ionic equations.

• Formulas that include only the particles that participate in reactions are called ________________________________.

____________________________________________

Types of Reactions in Aqueous Solutions (cont)• Some reactions produce more water molecules.

• No evidence of a chemical reaction is observable.Example) _________________________________________

■ Without spectator ions __________________________________

• Gases that are commonly produced are• __________________________, ________________________, and ________________________.

Example - 2HI(aq) + Li2S(aq) → H2S(g) + 2LiI(aq)

• Another example is mixing vinegar and baking soda, which produces _______________________________.

HCl(aq) + NaHCO3(aq) → H2CO3(aq) + NaCl(aq)

H2CO3(aq) decomposes immediately.

H2CO3(aq) → H2O(l) + CO2(g)

• ____________________________ can be ___________________ and represented by a ________________________________________.

Reaction 1 HCl(aq) + NaHCO3(aq) → H2CO3(aq) + NaCl(aq)

Reaction 2 H2CO3(aq) → H2O(l) + CO2(g)

Combined equation

__________________________________________________________________________

Overall equation

__________________________________________________________

Ch 10 Key Concepts• Some physical changes are evidence that indicate a chemical reaction has occurred. • Word equations and skeleton equations provide important information about a chemical reaction.• A chemical equation gives the identities and relative amounts of the reactants and products that are

involved in a chemical reaction. • Balancing an equation involves adjusting the coefficients until the number of atoms of each element is

equal on both sides of the equation.• Classifying chemical reactions makes them easier to understand, remember, and recognize.• Activity series of metals and halogens can be used to predict if single-replacement reactions will occur.• In aqueous solutions, the solvent is always water. There are many possible solutes.• Many molecular compounds form ions when they dissolve in water. When some ionic compounds dissolve

in water, their ions separate. • When two aqueous solutions that contain ions as solutes are combined, the ions might react with one

another. The solvent molecules do not usually react.• Reactions that occur in aqueous solutions are double-replacement reactions.