Download Chemical Reactions

Chemical Reactions
Activity
• On a blank sheet of paper, list all reactions
that you can think of.
– Ex: List animals
• Cat, dog, fish, alligator, horse, lion…
• Group the reactions you listed into columns
across your paper.
– Ex: Group animals
• Cat
Lion
Dog
Horse
Fish
Alligator
Activity
• Give a name to each group you formed.
– Do they blow up? Form a gas? Etc.
– Ex: Name animal groups
• Feline
Cat
Lion
Domestic
Dog
Horse
Aquatic
Fish
Alligator
• What group names did you come up with?
Activity
• How do we know that a chemical reaction has
occurred?
• Discuss: What criteria would you use to assess
if a chemical reaction has occurred?
Indicators of Chemical Reactions
•
•
•
•
Light and Heat
Gas
Precipitate
Color Change
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.
Word Equations
• Represent the reactants and products in a
chemical reaction with words
• Only uses qualitative descriptions
• Does not give quantities of products or
reactants
Methane + oxygen
carbon dioxide + water
Word Equations
• Reactants on the left, products on the right
•
= yield, produce, or form
Formula Equations
• Represents the reactants and products of a
chemical reaction by their symbols or
formulas
Methane + oxygen
CH4(g) + O2(g)
carbon dioxide + water
OR
CO2(g) + H2O(g)
Formula Equations
• Only uses qualitative descriptions; no
amounts of reactants or products
• To show the amounts of products and
reactants, the equation must be balanced
Balancing Equations
• Coefficients must be added to a formula
equation to be properly balanced.
CH4(g) + 2O2(g)
CO2(g) + 2H2O(g)
Practice
• Write word and formula equations for the
following reactions:
1. Aluminum reacts with oxygen to produce
aluminum oxide.
2. Iron (III) oxide reacts with carbon monoxide
to produce iron and carbon dioxide.
Practice
3. Solid sodium oxide is added to water at
room temperature and forms sodium
hydroxide (dissolved in the water).
4. Phosphoric acid is produced through the
reaction between tetraphosphorus decoxide
and water.
Practice
• Translate the following chemical equations
into a sentence:
1. CS2(l) + 3O2(g)
CO2(g) +2SO2(g)
2. BaCl2(aq) + Na2CrO4(aq)
BaCrO4(s) + 2NaCl(aq)
3. NaCl(aq) + AgNO3(aq)
NaNO3(aq) + AgCl(s)
Significance of Chemical Equations
• Debate: Pros vs. Cons of Chemical Equations
– Take two minutes to come up with your
arguments either for or against using chemical
equations.
Significance of Chemical Equations
1. The coefficients of a chemical reaction
indicate relative, not absolute, amounts of
reactants and products.
2. The relative masses of the reactants and
products of a chemical reaction can be
determined from the reaction’s coefficients.
3. The reverse reaction for a chemical equation
has the same relative amounts of substances
as the forward reaction.
Balancing Chemical Equations
1. Write the word equation for the reaction.
water
hydrogen + oxygen
2. Write the formula equation.
H2O(l)
H2(g) + O2(g)
3. Balance the formula equation according to
the law of conservation of mass.
4. Double check the number of atoms on each
side.
Steps:
a. Balance the different types of atoms one at a
time.
b. First balance the atoms of elements that only
appear once on each side of the equation.
c. Next balance all other atoms.
d. Balance H and O atoms LAST.
Practice
1. The reaction of zinc with aqueous
hydrochloric acid produces a solution of zinc
chloride and hydrogen gas.
2. Magnesium and hydrochloric acid react to
produce magnesium chloride and hydrogen.
3. Aqueous citric acid reacts with solid
magnesium hydroxide to produce aqueous
magnesium nitrate and water.
3-2-1
• 3 things you learned
• 2 connections you made
• 1 question you still have
Activity
• Groups of 3-4 people
• Design your own equation for your classmates
to balance.
• Each group will present their equation, so the
class can balance it.
• Be prepared to explain the correct balancing
and answer any questions from your
classmates.
Synthesis Reaction
• A + B → AB
1. 2Mg + O2 → 2MgO
2. Na(s) + Cl2(g) →
3. MgO + H2O →
4. Sodium reacts with fluorine to produce
sodium fluoride.
Combustion
• CxHy + O2→ CO2 + H2O
1. C10H8 + 12 O2 → 10 CO2 + 4 H2O
2. CH4(g) + O2(g) →
3. The burning of propane, C3H8, results in the
production of carbon dioxide and water
vapor.
Single- Displacement
• E+C→E+C
1. Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
2. Br2 + KCl →
3. Mg + HCl →
4. When solid aluminum is placed in aqueous
lead(II) nitrate, the aluminum replaces the
lead and solid lead and aqueous aluminum
nitrate are formed.
Double-Displacement
• AB + CD → CB + AD
1. NaCl + AgNO3 → NaNO3 + AgCl
2. HCl(aq) + NaOH(aq) →
3. KI + Pb(NO3)2 →
4. Iron (II) sulfide reactions with hydrochloric
acid to form hydrogen sulfide gas and iron (II)
chloride.
Decomposition
• C→
1. H2SO4 → H2O + SO3
2. HgO(s) →
3. KClO3 →
4. Calcium hydroxide decomposes to produce
calcium oxide and water.
Discuss
• What if there was no combustion reaction?
What would be different in your life?
• What would be an alternative to using the
activity series?
What type of reaction was this
demonstration?
A.
B.
C.
D.
E.
Synthesis Reaction
Decomposition Reaction
Single-Displacement Reaction
Double-Displacement Reaction
Combustion Reaction
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