Download Task Checklist:

Ms. K
Chemistry
Name_____________________________ #_____
Date______________________ Period_________
Pages 260-297
“The meeting of two personalities is like the contact of two chemical
substances; if there is any reaction, both are transformed.? ? Carl Jung
Task Checklist:
Look at Online Textbook Materials
Look at Section 1 Visual Concepts
Look at Section 2 Visual Concepts
Look at Section 3 Visual Concepts
Take Section 1 Self-Check Quiz
Take Section 2 Self-Check Quiz
Take Section 3 Self-Check Quiz
Do the Properties of Heat Concept Map
Other Tasks
Read Section 1
Read Section 2
Read Section 3
Review Chapter Packet
Examine Class Website
Review Chapter PowerPoint
Chapter 8:
Chemical Equations
and Reactions
Zn(s) + 2HCl(aq) → ZnCl2 (aq) + H 2 ↑
pp. 260-297
The evolution of energy as light
and heat is an indication that a
chemical reaction is taking place.
Describing Chemical Equations
chemical equations vs. chemical formulas ?
Heat Concepts
„
„
„
H2 + O2 →
H2O
2H2 + O2 → 2H2O
„
2H2(g) + O2(g) → 2H2O(g)
„
„
Exothermic or Endothermic?
2H2O(g) + 483.6 kJ → 2H2(g) + O2(g)
ΔE (ΔH) ? change in energy (ΔE) or change in heat (ΔH)
exothermic ? heat is released (given off) during a reaction (HOT)
endothermic ? heat is absorbed (taken in) during a reaction (COLD)
Example of a thermochemical equation:
Exothermic
2H2(g) + O2(g) → 2H2O(g) + 483.6 kJ
ΔH = -483.6 kJ
If ΔH is (-) or written into the equation on the right side,
the reaction is exothermic
If ΔH is (+) or written into the equation on the left side,
the reaction is endothermic.
Good Evidence of
a Chemical Reaction
(These sometimes can be
just a physical change?)
„
Color change
Example:
rusting
„
Energy change
Example:
glow stick
„
Gas released
Example:
vinegar and baking soda
„
Precipitate formed
Example:
solid formed from two liquids
Which piece(s)
of evidence is
represented in
each picture?
1
Equation Terminology
Phase Information
„
reactants on left
products on right
yield →
„
reversible reaction
„
(s), (l), (g), (aq)
gas - ↑, precipitate - ↓ ONLY FOR PRODUCTS
Δ ? heat written above the arrow
elect. ? electricity written above the arrow
catalyst written above the arrow (Ni, Pt, MnO2)
„
„
„
„
„
„
→
←
Five Types of Chemical Reactions
„ Synthesis (Direct Combination, Composition)
„ Decomposition
„ Combustion
„ Single
Hg and Br2 are liquids at room
temperature (l)
„ metals are usually solid (s)
„ nonmetals, use your prior knowledge
„ ionic compounds are usually solid (s)
„ covalent compounds, use your prior
knowledge
„
Synthesis
also known as
?combination?
element or + element or → compound
compound
compound
Replacement
(Single Displacement)
„ Double
Replacement
Example:
A
+
B
→
AB
2C
+
O2
→
2CO
(Double Displacement)
compound → two or more elements
or compounds
AB
→
A
+
B
2H2O
→
2H2
+
O2
Combustion
anything + oxygen → heat
hydrocarbon + oxygen → carbon dioxide + water
CxHy + O2 → CO2 + H2O
Example:
+
EXOTHERMIC
One reactant used
→
→
+
Decomposition during the reaction.
also known as ?analysis?
Example:
One product formed
during the reaction.
CH4 + 2O2 → CO2 + 2H2O
+
→
+
2
Single Replacement
Double Replacement
1 element and 1 compound in the
reactants with 1 element and 1
compound in the products.
Example:
A
+
BC → AC +
B
Zn + H3PO4 → Zn3(PO4)2 + H2
3Zn + 2H3PO4 → Zn3(PO4)2 + 3H2
Checking for Understanding
Classify the following reactions as one of the 5 types:
3Pb(NO3)2(aq) + 2K3PO4(aq) → Pb3(PO4)2(s) + 6KNO3(aq)
2C8H18(l) + 25O2(g) → 16CO2(g) + 18H2O(g)
Cl2(g) + 2NaBr(aq) → 2NaCl(aq)+ Br2(l)
1 compound and 1 compound in the
reactants with 1 compound and 1
compound in the products.
AB +
Example:
CD
→ AD +
CB
Pb(NO3)2(aq) + 2NaI(aq) → PbI2(s) + 2NaNO3(aq)
precipitate
Characteristics of Chemical
Equations
The equation must represent known facts.
„ The equation must contain the correct
formulas for the reactants and products.
„ The law of conservation of mass must be
satisfied (balanced).
„
C12H22O11(s) → 12C(s) + 11H2O(l)
2H2O(l) + O2(g) → 2H2O2(aq)
Balancing Equations
Balancing Equations
1770s
„ Law
of Conservation
of Matter –
matter cannot be
created nor destroyed
CH4 + O2 → H2O + CO2
16g + 32g → 18g + 44g
48g ≠ 62g
Antoine Lavoisier
coefficient ? a small, whole number that appears
in front of a formula in a chemical equation
3
Coefficients
„
„
„
„
coefficient ? a small, whole
number that appears in front
of a formula in a chemical
equation
Coefficients express relative, not absolute
amounts of reactants and products.
Coefficients represent individual particles of
matter.
Because particles and moles are directly
proportional, the coefficients also represent the
number of moles of each substance.
Because mass and moles are NOT directly
proportional, the coefficients DO NOT represent
the mass of each substance.
Balancing Chemical Equations
When balancing, you do not
rewrite the formulas. You only
place coefficients in the
equation.
NEVER change the subscripts
after the equation is written!
Balancing Equations
Balancing Equations
Example:
Example:
CaCl2 + NH4OH →
C6H12O6
+
O2 →
H2O +
CO2
Ca(OH)2 +
NH4Cl
Since these are ionic compounds, balance the ions as whole items.
Double check to be sure you are done.
Are the coefficients in the lowest ratio?
.
Word Equations
Double check to be sure you are done.
Are the coefficients in the lowest ratio?
.
Diatomic Molecules
word equation ? an equation in which the reactants
and products in a chemical reaction are
represented by words.
„ Chemical equations are expressed in formulas.
„ Chemists use words to communicate verbally.
„ It is necessary to be able to take the words and
express them as equations and vice versa.
H2, O2, N2, F2, Cl2, Br2, I2
4
The Hungry Dragon
Synthesis
also known as
c
? ombination?
Potassium chlorate
decomposes with the use
of heat to form potassium
chloride and oxygen.
Upon placing glucose in the
reaction mixture, the
glucose reacts with the
oxygen exothermically.
Synthesis (Binary)
also known as
c
? ombination?
If a metal and a nonmetal come together,
form the ionic compound according to the
charges of the ions formed.
Example: Na(s) + Cl2(g) → NaCl(s)
NOT NaCl2
Balance: 2Na(s) + Cl2(g) → 2NaCl(s)
Synthesis Reactions with Oxides
Oxides of active metals react with water to
produce metal hydroxides.
CaO(s) + H2O(l) → Ca(OH)2(s)
Oxides of nonmetals react with water to form
oxyacids.
One product formed
during the reaction.
element or
element or
compound
→
+
compound
compound
Example:
A
+
B
→
AB
2C
+
O2
→
2CO
+
→
Synthesis (Binary)
also known as
c
? ombination?
If two nonmetals come together, form the
simplest compound from the two.
Example: C(s) + O2(g) → CO(g)
NOT CO2(g)
Balance: 2C(s) + O2(g) → 2CO(g)
Synthesis Reactions with Oxides
Certain metal oxides and nonmetal oxides
react with each other to form salts (ionic
compounds).
CaO(s) + SO2(g) → CaSO3(s)
SO2(g) + H2O(l) → H2SO3(aq)
2H2SO3(aq) + O2 → 2H2SO4(aq)
5
One reactant used
You Try It.
Decomposition during the reaction.
also known as ?analysis?
Predict the products of the following
reactions:
compound → two or more elements
or compounds
2 Al(s) + 3 Br2(l) →
Na2O(s) + H2O(l) →
N2O5(g) + H2O(l) →
Example:
AB
→
A
+
B
2H2O
→
2H2
+
O2
MgO(s) + CO2(g) →
+
→
Decomposition
Decomposition
also known as ?analysis?
also known as ?analysis?
Decomposition often needs a ?push?. It is
not uncommon to see symbols over the
yield sign, indicating that a catalyst, heat,
or electricity was used.
Table sugar will decompose to form
carbon and water when sulfuric
acid is used as a catalyst.
Pt
catalyst
→
Δ
heat →
elect.
electricity →
(write the specific catalyst)
also known as ?analysis?
When a compound decomposes or breaks
down, it does not immediately go to pure
elements. First, it breaks down into
smaller compounds if possible.
Example: H2O2(aq) → H2O(l) + O2(g)
Balance: 2H2O2(aq) MnO
→ 2H2O(l) + O2(g)
Combustion
anything + oxygen → heat
EXOTHERMIC
Decomposition
MnO2
2
Example: H2O(l) → H2(g) + O2(g)
Balance: 2H2O(l) elect.
→ 2H2(g) + O2(g)
hydrocarbon + oxygen → carbon dioxide + water
CxHy + O2 → CO2 + H2O
elect.
Example:
CH4 + 2O2 → CO2 + 2H2O
+
→
+
6
Single Replacement
I want to cut
in, but am I
more reactive
than she is?
Single Replacement
1 element and 1 compound in the
reactants with 1 element and 1
compound in the products.
Example:
A
+
BC → AC +
B
Zn + H3PO4 → Zn3(PO4)2 + H2
3Zn + 2H3PO4 → Zn3(PO4)2 + 3H2
cation/anion
Single Replacement
I want to cut in,
but am I more
reactive than
he is?
+
element
Single Replacement
The metal element will only react with the
compound if it is more reactive on the
activity series.
The nonmetal element will only react with
the compound if it is more reactive.
F2 > Cl2 > Br2 > I2
cation/anion
Single
Replacement
decreasing
activity
+
element
lithium
potassium
calcium
sodium
magnesium
aluminum
zinc
chromium
iron
nickel
tin
lead
HYDROGEN
copper
mercury
silver
platinum
gold
Single Replacement Video
http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/024_SILVERCRYSTA.MOV
7
Double Replacement
Double Replacement
1 compound and 1 compound in the
reactants with 1 compound and 1
compound in the products.
AB +
Example:
CD
→ AD +
CB
Pb(NO3)2(aq) + 2NaI(aq) → PbI2↓ + 2NaNO3(aq)
precipitate
cation/anion + cation/anion → cation/anion + cation/anion
cation/anion
Most double replacement reactions are run in water.
+
cation/anion
Double Replacement
Double Replacement
precipitate ? a solid that is produced as a
result of a chemical reaction in solution
and that separates from the
solution?therefore it is NOT soluble in
water. (insoluble)
Memorize for dissolving in water:
„ Alkali metal compounds are soluble
„ NH4+ compounds are soluble
„ NO3- compounds are soluble
„ C2H3O2- compounds are soluble
„ ClO3- compounds are soluble
„ CO3-2, PO4-3, O-2, SiO3-2, S-2, SO4-2 are
generally not soluble (insoluble)
How do you know which product is a
precipitate, if any?
Oxidation-Reduction Reactions
Page 631
Oxidation-Reduction Reactions
Redox Reactions
„
oxidation processes ? reactions in which
the atoms or ions of an element
experience an increase in oxidation state
(losing electrons)
„
reduction processes ? reactions in which
the oxidation state of an element
decreases (gaining electrons)
8
L osing
E lectrons
O xidation
the lion goes G aining
E lectrons
R eduction
Oxidation-Reduction Reactions
2Cu(s) + O2(g) → 2CuO(s)
What is the oxidation number of O2(g)?
What is the oxidation number of O in the
CuO(s)?
Oxidation-Reduction Reactions
2Cu(s) + O2(g) → 2CuO(s)
What is the oxidation number of Cu(s)?
What is the oxidation number of Cu in the
CuO(s)?
Oxidation-Reduction Reactions
2Na(s) + Cl2(g) → 2NaCl(s)
Oxidation numbers:
Na(s):
Cl2(g):
Na in NaCl(s):
Cl in NaCl(s):
Oxidation-Reduction Reactions
Acetylene gas is burned.
C2H2(g) +
What is happening to the O2?
What is happening to the C?
What is happening to the H?
9
Ms. K
Chemistry
Name_____________________________ #_____
Date______________________ Period_________
Classification of Chemical Reactions
Classify the reactions below as synthesis, decomposition, single replacement, double replacement,
or combustion. A few reactions are both synthesis and combustion.
1. 2H 2 + O 2 → 2H 2 O
2. 2H 2 O
elect
→ 2H 2 + O 2
________________________
________________________
3. Zn + H 2SO 4 → ZnSO 4 + H 2
________________________
4. 2CO + O 2 → 2CO 2
________________________
Δ
5. 2HgO ⎯⎯
→ 2Hg + O 2
________________________
6. 2KBr + Cl2 → 2KCl + Br2
________________________
7. CaO + H 2 O → Ca(OH) 2
________________________
8. AgNO3 + NaCl → AgCl + NaNO3
________________________
Pt
9. 2H 2 O 2 ⎯⎯
→ 2H 2 O + O 2
________________________
10. Ca(OH) 2 + H 2SO 4 → CaSO 4 + 2H 2 O
________________________
Ms. K
Chemistry
Name_____________________________ #_____
Date______________________ Period_________
Balancing Chemical Equations
Balance the equations below by placing the appropriate coefficients before each substance. Also, classify the
reactions below as synthesis, decomposition, single replacement, double replacement, or combustion. A few
reactions are both synthesis and combustion. Place your classification(s) in the blank.
______________________________1.
N2(g)
+
H2(g)
______________________________2.
KClO3 (s)
______________________________3.
NaCl(aq)
______________________________4.
H2(g)
______________________________5.
AgNO3(aq) + MgCl2(aq) → AgCl(s) + Mg(NO3)2(aq)
______________________________6.
AlBr3(aq)
______________________________7.
CH4(g)
______________________________8.
C3H8(g)
______________________________9.
C8H18(g)
______________________________10.
FeCl3(aq)
+
______________________________11.
P4(s)
O2(g)
______________________________12.
Na(s) + H2O(l)
______________________________13.
Ag 2 O(s)
Δ
⎯⎯
→
______________________________14.
S8(s)
O2(g)
______________________________15.
CO2(g)
______________________________16.
K(s)
______________________________17.
HCl(aq) + CaCO3(aq) → CaCl2(aq) + H2O(l) + CO2(g)
______________________________17.
Number 17 has two reactions happening…one then the other.
Δ
⎯⎯
→
O2(g)
+
+
+
+
→
→
O2(g)
→
NaOH(aq)
→
→
H2O(l)
MgBr2(aq)
NaF(aq)
+
Cl2(g)
→
KBr(aq)
CO2(g)
+
CO2(g)
→
Al2(SO4)3(s)
H2O(l)
+
CO2(g)
+
H2O(l)
+
H2O(l)
Fe(OH)3(s)
+
NaCl(aq)
P2O5(s)
NaOH(aq)
Ag(s)
→
+ O2 (g)
H2O(l)
K2SO4(aq)
O2(g)
+
+
→
→
O2(g)
+
NH3(g)
KCl(s)
F2(g)
+
+
+
→
+
+
H2(g)
O 2 (g)
SO3(g)
→
C6H12O6(s)
→
KBr(aq)
+
+
O2(g)
Mg(s)
Balancing Hints:
•
•
•
•
•
•
Only place coefficients in front. Never, never, never (and I mean NEVER) change the subscripts after the correct formula is written.
For single and double replacement reactions, balance the polyatomic ions as a whole item if they appear on both sides of the equation.
For single and double replacement reactions, change H2O to HOH and balance H+ ions and OH- ions.
Balance lone elements first. Lone elements are ones that only appear in one formula on each side. Leave the ones that appear more than once on a side
until last.
When you are done, the coefficients need to be in the lowest possible ratio. Always recheck this.
Recheck that all atoms are balanced when you are done.
Mrs. K
Chemistry
Name____________________________________ #_____
Date_____________________________ Period_________
Word Equations
Write the word equations below as chemical equations AND balance. Include the phase information: (s), (l), (g), & (aq).
Refer to your notes for phase information. If a single replacement or double replacement reaction is taking place, the
ionic compounds are likely dissolved in water.
1. Zinc plus lead(II) nitrate yield zinc nitrate plus lead.
2. Aluminum bromide and chlorine yield aluminum chloride and bromine.
3. Sodium phosphate combined with calcium chloride will yield solid calcium phosphate and sodium chloride.
4. Potassium chlorate when heated yields potassium chloride and oxygen gas.
5. Aluminum and hydrochloric acid yield aluminum chloride and hydrogen gas.
6. Calcium phosphate and water are produced when calcium hydroxide and phosphoric acid are mixed.
7. Copper plus sulfuric acid yield copper(II) sulfate plus water plus sulfur dioxide.
8. Nitrogen gas can be made from the mixture of hydrogen and nitrogen monoxide. Water is a byproduct.
Ms. K
Honors Chemistry
Name_____________________________ #_____
Date______________________ Period_________
SYNTHESIS WORKSHEET
Predict the products of the reaction below. Write the balanced equation. Include the phase
information. Remember, ionic compounds are usually solid. Watch out for those diatomic molecules.
Example:
H2(g) + I2(g) → 2 HI(s)
Example:
2Mg(s) + O2(g) → 2MgO(s)
1.
Mg(s)
+
2.
CO2(g)
3.
CO(g)
4.
Al(s)
5.
MgO(s)
6.
K(s)
7.
CaO(s)
N2(g)
+
H2O(l)
+
+
+
+
→
O2(g)
→
Cl2(g)
→
H2O(l)
Br2(l)
+
→
→
→
CO2(g)
→
Ms. K
Honors Chemistry
Name_____________________________ #_____
Date______________________ Period_________
Decomposition Worksheet
Predict the products of the reaction below. Write the balanced equation. Include the
phase information. Remember, ionic compounds are usually solid. Watch out for those
diatomic molecules.
elect.
Example:
2H 2 O(l)
Example:
2HgO(s)
1.
Fe 2 O3 (s)
2.
NaCl(s)
3.
NH3 (g)
4.
CaF2 (s)
5.
H 2 O 2 (aq)
→
Δ
⎯⎯
→
elect.
elect.
2H 2 (g)
2Hg(l)
+
+
O2 (g)
O2 (g)
→
→
Δ
⎯⎯
→
elect.
→
MnO 2 (s)
→
When a metal carbonate is heated, it breaks down to produce a metal oxide and carbon
dioxide gas.
Δ
6.
CaCO3 (s) ⎯⎯
→
Metal hydroxides will often decompose when heated to yield metal oxides and water.
Δ
7.
Ca(OH) 2 (s) ⎯⎯
→
When a metal chlorate is heated, it decomposes to produce a metal chloride and oxygen.
Δ
8.
KClO3 (s) ⎯⎯
→
Certain acids decompose into nonmetal oxides and water.
Δ
9.
H 2SO 4 (aq) ⎯⎯
→
Ms. K
Chemistry
Name____________________________________ #_____
Date_____________________________ Period_________
Combustion
hydrocarbon ? a compound containing hydrogen and carbon
alkane – a hydrocarbon with the formula CxH2x+ 2
Write the entire balanced chemical equation for each combustion reaction.
1. the burning of methane
2. the combustion of pentane
3. the combustion of hydrogen
4. the burning of isopropyl alcohol, C3H8O
5. the combustion of glucose