Chapter 6 Notes
Science 10
Name: ________________
6.1 Types of Chemical Reactions
a) Synthesis (A + B → AB)
Synthesis reactions are
also known as _________
reactions. When this
occurs two or more
reactants (usually
elements) join to form a
_________.
A + B → AB, where A and B represent elements
The elements may form _________ compounds, like the following:
• Sodium metal and chlorine gas combine to form sodium chloride.
• 2Na + Cl2 → 2NaCl
• Magnesium metal reacts with oxygen gas to form magnesium oxide.
• 2Mg + O2 → 2MgO
Or the elements may form _________ compounds, like the following:
• Nitrogen gas and oxygen gas join to form dinitrogen monoxide.
• 2N2 + O2 → 2N2O
Practice Problems
1. Complete and balance the following synthesis (combination) reactions. Remember to consider the
chemical formulas of the products carefully before you begin to balance.
(a) ____Mg + ____N2 ➔
(b) ____Al + ____F2 ➔
(c) ____K + ____O2 ➔
(d) ____Cd + ____I2 ➔
(e) ____Cs + ____P4 ➔
1
Chapter 6 Notes
Science 10
Name: ________________
2. Identify whether or not each of the following chemical equations is a synthesis (combination)
reaction.
(a) 2H2 + O2 ➔ 2H2O
(d) S8 + 12O2 ➔ 8SO3
(b) 2Al + 3CuCl2 ➔ 2AlCl3 + 3Cu
(e) 2Ti + 3 Cl2 ➔ 2TiCl3
(c) 2KClO3 ➔ 2KCl + 3O2
b) Decomposition (AB → A + B)
Decomposition reactions
are the _________ of
synthesis reactions.
A compound _________
down into two or more
products (often
elements).
AB → A + B where A and B represent elements
Ionic compounds may _________ to produce elements, like the following:
Table salt, sodium chloride, can be broken down into sodium metal and
chlorine gas by _________ salt at 800ºC and running _________ through it.
• 2NaCl → 2Na + Cl2
Or covalent compounds may decompose into elements, like the following:
By running _________ through water, the water molecules _________ into
hydrogen and oxygen gases.
2H2O → 2H2 + O2
2
Chapter 6 Notes
Science 10
Name: ________________
Practice Problems
1. Complete and balance the following decomposition reactions. Remember to check for diatomic
elements as you write the formulas of the products.
(a) ____AuCl3 ➔
(b) ____K2O ➔
(c) ____MgF2 ➔
(d) ____Ca3N2 ➔
(e) ____CsI ➔
2. Identify each reaction as synthesis, decomposition, or neither.
(a) CO2 ➔ C + O2
(b) 2AgCl + Cu ➔ CuCl2 + 2Ag
(c) 2Cr + 3F2 ➔ 2CrF3
(d) CaI2 + Na2CO3 ➔ 2NaCl + CaCO3
(e) 2NaClO3 ➔ 2NaCl + 3O2
c) Single Replacement
Single replacement reactions replace one element from a compound with a
separate element added as a reactant.
A compound and an element react, and the element switches places
with part of the original compound.
A + BC → B + AC where A is a _________, or
A + BC → C + BA where A is a _____-metal
3
Chapter 6 Notes
Science 10
Name: ________________
When A is a metal:
Aluminum foil in a solution of copper(II) chloride produces solid copper
and aluminum chloride.
2Al + 3CuCl2 → 3Cu + 2AlCl3
When A is a non-metal:
When fluorine is bubbled through a sodium iodide solution, iodine and
sodium fluoride are produced.
F2 + 2NaI → I2 + 2NaF
Practice Problems
1. Complete and balance the following single replacement reactions.
(a) ____PbCl4 + ____Al ➔
(b) ____Na + ____Cu2O ➔
(c) ____CuF2 + ____Mg ➔
(d) ____Cl2 + ____CsBr ➔
(e) ____Be + ____Fe(NO3)2 ➔
2. Classify each reaction as synthesis, decomposition, or single replacement.
(a) 2N2O ➔ 2N2 + O2
(b) Au(NO3)3 + 3Ag ➔ Au + 3AgNO3
(c) CH4 ➔ C + 2H2
(d) 2NH4Br + Cl2 ➔ 2NH4Cl + Br2
(e) Br2 + I2 ➔ 2IBr
4
Chapter 6 Notes
Science 10
Name: ________________
d) Double Replacement (AB + CD AD + CB)
Double replacement reactions _________ elements between two compounds
reacting together to form two new compounds.
Two compounds react, with elements _________ places between the
original compounds.
Two solutions react to form a _________ (ppt, solid) and another
solution
Ionic solution + ionic solution → ionic solution + ionic _________
AB + CD → AD + CB
When potassium chromate and silver nitrate react, they form a red
_________, silver chromate, in a _________ of potassium nitrate.
K2CrO4 + 2AgNO3 → Ag2CrO4 + 2KNO3
Practice Problems
1. Complete and balance the following double replacement reactions. You do not need to decide which
product(s) form a precipitate or to show states in the balanced equation.
(a) ____CaS + ____NaOH ➔
(b) ____K3PO4 + ____MgI2 ➔
(c) ____SrCl2 + ____Pb(NO3)2 ➔
(d) ____AlCl3 + ____CuNO3 ➔
5
Chapter 6 Notes
Science 10
Name: ________________
(e) ____AgNO3 + ____Na2CrO4 ➔
2. Classify each reaction as synthesis, decomposition, single replacement, or double replacement.
(a) 2FeBr3 + 3Zn ➔ 3ZnBr2 + 2Fe
(b) FeBr2 + ZnSO4 ➔ ZnBr2 + FeSO4
(c) 2Al + Fe2O3 ➔ 2Fe + Al2O3
(d) 2Fe + O2 ➔ 2FeO
(e) 2FeBr3 ➔ 2Fe + 3Br2
e) Neutralization (Acid-Base Reactions)
Neutralization reactions occur when an acid (most compounds starting with H)
and a _________ (most compounds ending in OH, or beginning with NH4) react
to form a salt and _________.
• Acid + base → salt + water
• HX + MOH → MX + H2O where X and M are elements
• Sulfuric acid is used to neutralize calcium _________:
H2SO4 + Ca(OH) 2 → CaSO4 + 2H2O
• Phosphoric acid helps to neutralize the compounds that cause rust, such as
iron(II) _________.
H3PO4 + 3Fe(OH)2 → Fe3(PO4)2 + 6H2O
Practice Problems
1. Complete and balance the following neutralization (acid-base) reactions.
(a) ____HBr + ____NaOH (b) ____H3PO4 + ____Mg(OH)2 (c) ____HCl +____Pb(OH)2 (d) ____Al(OH)3 + ____HClO4 6
Chapter 6 Notes
Science 10
Name: ________________
2. Classify each reaction as synthesis, decomposition, single replacement, double
replacement, or neutralization.
(a) 2HCl + Zn ZnCl2 + H2
(b) 2HCl H2 + Cl2
(c) 2HCl + Sr(OH)2 SrCl2 + 2H2O
(d) 2HCl + Pb(NO2)2 2HNO2 + PbCl2
f) Combustion
Combustion reactions occur when a compound or element reacts with ______
to release _________ and produce an _________.
• Also sometimes referred to as ___________combustion.
• CXHY + O2 → CO2 + H2O where X and Y represent integers
• Natural gas (_________) is burned in furnaces to heat homes.
CH4 + O2 → CO2 + 2H2O
• An acetylene torch is used to _________ metals together.
2C2H2 + 5O2 → 4CO2 + 2H2O
• Carbohydrates like glucose combine with oxygen in our body to release
energy.
C6H12O6 + 6O2 → 6CO2 + 6H2O
Practice Problems
1. Complete and balance the following combustion reactions.
(a) C3H8 + O2 ➔
(b) C4H10 + O2 ➔
(c) C2H4 + O2 ➔
7
Chapter 6 Notes
Science 10
Name: ________________
(d) C6H12O6 + O2 ➔
(e) C12H22O11 + O2 ➔
2. Classify each reaction as synthesis, decomposition, single replacement, double replacement,
neutralization, or combustion.
(a) 3Ca(NO3)2 + 2Na3PO4 ➔ 6NaNO3 + Ca3(PO4)2
(b) Ca(OH)2 + H2SO4 ➔ 2H2O + CaSO4
(c) 2C6H6 + 15O2 ➔ 12CO2 + 6H2O
(d) 6Mg + P4 ➔ 2Mg3P2
(e) C2H6O + 3O2 ➔ 2CO2 + 3H2O
Summary of Types of Chemical Reactions
8
Chapter 6 Notes
Science 10
Name: ________________
Practice Problems
For each of the following reactions, classify the reaction type and then predict what the products will be.
Then write the skeleton equation and balance it.
1. ____Fe2O3 ➔
2. ____Al + ____NiBr3 ➔
3. ____Cl2 +____NiBr2 ➔
4. ____HCl + ____Mg(OH)2 ➔
5. ____C18H38 + ____O2 ➔
6. ____Li + ____N2 ➔
7. ____AgNO3 + ____Na2CrO4 ➔
6.2 Factors Affecting the Rate of Chemical Reactions
Often, controlling the rate of a chemical reaction is as important as having the
reaction occur in the first place. Altering certain factors can determine the _____
at which a chemical reaction occurs.
• To make a reaction happen quickly:
Increase the _________ where the reaction occurs.
Increase the _________ of reactants.
Increase the amount of _________ area that reacts.
Add a _________ or remove an _________.
• To make a reaction happen slowly:
_________ the temperature where the reaction occurs.
_________ the concentration of reactants.
_________ the amount of surface area that reacts.
_________ a catalyst or _________ an inhibitor.
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Chapter 6 Notes
Science 10
Name: ________________
a) Temperature
• Temperature is the _________ energy of molecules.
The more energy molecules have, the higher the temperature.
When molecules have more energy, they _________ around more,
_________ into other molecules more, and therefore react _________.
• The rate of reaction changes with the temperature.
Higher temperature = _________ reaction rate, and vice versa.
Sometimes we want slower reactions (we use a _________ to prevent
spoilage).
Sometimes we want faster reactions (we _________ food to speed up
the production of new molecules).
Learning Check (p. 272-274)
1. Heating a light stick can make it glow brighter. Why?
The brighter light of a hot glow stick is due to a faster reaction rate caused by heating.
2. What happens to the rate of a chemical reaction when the temperature is raised?
Raising the temperature of a chemical reaction increases the reaction rate.
3. What does cooling do to the frequency at which particles of reactants can collide?
Cooling decreases the frequency at which particles of reactants can collide.
4. How does cooling affect the energy of the collisions between particles?
Cooling lowers the energy of the collisions between reactant particles.
b) Concentration
Concentration refers to how many molecules of a substance exist in a certain
_________.
• Concentration is how much _________ is dissolved in _________.
• Concentration is measured in mass per unit volume (g/L).
10
Chapter 6 Notes
Science 10
Name: ________________
• Usually, the higher the concentration of reactants, the faster the reaction
occurs.
Since there are _________ molecules per unit volume in high
concentrations, there are more __________________ for molecules
to collide and react.
A splint of wood glows brighter in highly _____________ oxygen than
in normal _________ with a lower concentration of oxygen.
c) Surface Area
Chemical reactions occur when and where atoms and compounds collide.
Therefore, the more atoms and molecules there are to collide, the higher the
reaction rate.
• Increasing surface area _________ the rate of reaction.
• Surface area can be increased by creating _________ pieces.
• A _________ substance has far more surface area than one large _________.
• The increase in surface area must also be exposed for reaction; a powder only
reacts more quickly if it is in contact with the other reactant(s).
Reading Check (p. p. 275-276)
1. How does increasing concentration result in an increase in reaction rate?
2. Can the concentration of a substance change if it is a gas?
3. Can the concentration of a solution change if it is an aqueous solution?
11
Chapter 6 Notes
Science 10
Name: ________________
4. How does increasing the surface area of a reactant increase reaction rate?
d) Catalysts
Sometimes, increasing the temperature or concentration is not a desirable method
to increase reaction rate. Changing these two variables may be impractical or
dangerous. An alternate technique is to use a catalyst. A catalyst is a chemical
that allows a reaction to occur more _________ without actually participating in
the reaction itself.
• The catalyst speeds up the reaction rate but does not get _________ up as a
reactant.
• Catalysts often _________ the amount of energy necessary to break the bonds
in the reactants.
• _________ are an example of biological catalysts.
• Saliva has enzymes that help speed the breakdown of
_________ when they enter the mouth.
• A catalytic converter is a device installed in cars to _________ _________.
Car exhaust passes through the catalytic converter before leaving the
car.
Catalysts found in the honeycomb-shaped filters in the converter help to
change many of the pollutants into _________ _________ substances.
_________ carbon monoxide is changed into CO2.
Hydrocarbons are converted into CO2 and _________.
Nitrogen oxides are changed into _________ and _________.
Non-metal
oxide
• 2N2O3 → 2N2 + 3O2
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