Chapter 11 – Chemical Reactions

• There are many types of chemical reactions. We will study 5 of these. By being able to identify the type of chemical reaction that will occur, one can predict the products of a chemical reaction.

Chemical Reactions

• Chemical equations• In chemistry, it is useful to write the

chemical formulas of the reactants and products.

• An arrow is placed between them to show the direction of the chemical reaction.

Reactants (state) Products (state)

Chemical Reactions

• Chemical equations• Chemical formulas are used along with

the state of the substance written as a subscript in parenthesis.

• A ‘+’ sign is placed between each reactant and each product to show if multiple substances are either reactants or products.

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

Chemical Reactions

• Chemical equations• An (s) indicates that the substance is in

the solid state.• A (l) indicates that the substance is in the

liquid state.• A (g) indicated that the substance is in

the gaseous state.• An (aq) indicates that the substance is in

the aqueous state or dissolved state.

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

Chemical Reactions

• Chemical equations• Write the chemical equation when iron

metal reacts with oxygen gas to produce rust, iron (III) oxide.

Fe (s) + O2 (g) Fe2O3 (s)

Chemical Reactions

• Chemical equations• Balancing Chemical Equations• According to the Law of Conservation of

Mass, the number of atoms on the reactant side of the equation must equal the number of atoms on the product side.

• We can adjust the number of atoms on each side of the equation by placing coefficients in front of each substance.

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

Chemical Reactions

• Chemical equations• Balancing Chemical Equations

__Pb(NO3)2 (aq) + __KI (aq) __KNO3 (aq) + __PbI2(s)

__Na (s) + __CaCl2 (aq) __NaCl (aq) + __Ca(s)

Chemical Reactions

• Chemical equations• Write the chemical equation when zinc

metal reacts with aqueous silver nitrate to produce silver metal and aqueous zinc nitrate.

Chemical Reactions

• Chemical equations• Write the chemical equation when

aqueous potassium iodide reacts with aqueous lead (II) nitrate to produce aqueous potassium nitrate and solid lead (II) iodide.

Chemical Reactions

• 5 Types of Chemical Reactions• Synthesis (Combination) Reactions – 2

particles combine to form 1 larger particle.

A + B AxBy

Na (s) + O2 (g) Na2O (s)

Chemical Reactions

• 5 Types of Chemical Reactions• Synthesis (Combination) Reactions –

Predict the products in following the chemical reaction;

Al (s) + O2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Decomposition Reactions – 1 particle

splits into 2 smaller particles. AxBy A + B

H2CO3 (aq) H2O (l) + CO2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Decomposition Reactions – Predict the

products of the chemical reaction when sodium chloride is heated until is decomposes.

NaCl (s)

Chemical Reactions

• 5 Types of Chemical Reactions• Combustion Reactions – An element or

molecule reacts with oxygen gas that produces products which have oxygen chemically bonded to them.

A + O2 (g) AXOy

The ratio of ‘A’ to oxygen will vary depending on the charge of ‘A’.

Chemical Reactions

• 5 Types of Chemical Reactions• Combustion Reactions Mg (s) + O2 (g) MgO (s)

Fe (s) + O2 (g) Fe2O3 (s)

Technically, the rusting of iron is a combustion reaction.

Chemical Reactions

• 5 Types of Chemical Reactions• Combustion Reactions – These reactions

will always produce heat. If the molecule reacting with the oxygen gas is a hydrocarbon, then the products will always be carbon carbon dioxide and water.

CH4 (g) + 2O2 (g) CO2 (g) + 2H2O (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Combustion Reactions – Predict the

products of the chemical reaction were butane, (C4H6) burns.

C4H6 (g) + O2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Single Replacement Reactions – Either a

metal replaces a metal in an ionic compound, or a nonmetal replaces a nonmetal in an ionic compound.

A + BC AxCy + B

Al (s) + Cu(NO3)2 (aq) Al(NO3)3 (aq) + Cu (s)

NaCl (aq) + F2 (g) NaF (aq) + Cl2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Single Replacement Reactions – You need a

reference chart called an Activity Series to determine if one element can replace the one in the compound.

A + BC AC + B‘A’ has to be higher up on the Activity Series in

order to replace ‘B’.

Chemical Reactions• 5 Types of Chemical Reactions

• Single Replacement Reactions

Chemical Reactions• 5 Types of Chemical Reactions

• Single Replacement Reactions – Determine if a chemical reaction will occur between silver nitrate and calcium metal. If it does, predict the products of the chemical reaction.

• Ca (s) + AgNO3 (aq)

Chemical Reactions• 5 Types of Chemical Reactions

• Single Replacement Reactions – What will happen when solid lithium fluoride is exposed to liquid chlorine gas?

LiF (s) + Cl2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Double Replacement Reactions – The cations of

two ionic compounds switch anions. AB + CD AD + CD

• But one of the products has to be one of the following;• 1.) insoluble in water• 2.) a gas• 3.) a water molecule

Chemical Reactions

• 5 Types of Chemical Reactions• Double Replacement Reactions

• AgNO3 (aq) + NaCl (aq) NaNO3 (aq) + AgCl (s)

• HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l)

• HNO3 (aq) + NaHCO3 (aq) NaNO3 (aq) + H2O (l) + CO2 (g)

Chemical Reactions

• 5 Types of Chemical Reactions• Double Replacement Reactions – A solubility

table must be used in order to determine whether or not an ionic compound will be soluble in water or not.

• Some general rules regarding solubility;• All nitrates are soluble.• All compounds that have ammonium as the cation is

soluble.• Salts containing lead, mercury, and silver are

generally not soluble but there are some exceptions.

Chemical Reactions

• 5 Types of Chemical Reactions• Double Replacement Reactions – Will a

chemical reaction occur when aqueous solutions of sodium chloride and lead (II) nitrate are mixed? If so, what are the products?

NaCl (aq) + Pb(NO3)2 (aq)

Chemical Reactions

• 5 Types of Chemical Reactions• Double Replacement Reactions – What will

happen when aqueous solutions of potassium chloride and sodium hydroxide are mixed?

KCl (aq) + NaOH (aq)

Chemical Reactions• 5 Types of Chemical Reactions

• All types of chemical reactions – Predict the products of the following chemical reactions;

1. CaCO3 (s)

2. Li (s) + NaOH (aq)

3. Mg (s) + N2 (g)

4. Na2SO4 (aq) + Ba(NO3)2 (aq)

Chemical Reactions

• Net Ionic Equations• A chemical equation which only the ions that

participate in the formation of the non-aqueous product are written.

General Equation: Na2SO4 (aq) + Ba(NO3)2 (aq 2NaNO3 (aq) + BaSO4 (s)

Ionic Equation: 2Na+1 (aq) + SO4-2 (aq) + Ba+2 (aq) + 2NO3

-1 (aq) 2Na+1 (aq) + 2 NO3

-1 (aq) + BaSO4 (s)

Net Ionic Equation: Ba+2 (aq) + SO4-2 (aq) BaSO4 (s)

Chemical Reactions

• Net Ionic Equations

• Ions that do not participate in the net ionic equation are called spectator ions.

General Equation: Na2SO4 (aq) + Ba(NO3)2 (aq 2NaNO3 (aq) + BaSO4 (s)

Ionic Equation: 2Na+1 (aq) + SO4-2 (aq) + Ba+2 (aq) + 2NO3

-1 (aq) 2Na+1 (aq) + 2NO3

-1 (aq) + BaSO4 (s)

Net Ionic Equation: Ba+2 (aq) + SO4-2 (aq) BaSO4 (s)

Chemical Equations

• Writing Net Ionic Equations

• Write the net ionic for the chemical reaction between sodium dichromate and mercury (II) nitrate.