CHEMICAL EQUATIONS
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Transcript CHEMICAL EQUATIONS
CHEMICAL REACTIONS
The process by which one or more substances are
changed into one or more different substances
Word Equations
To write a word equation,
Write the names of the reactants to the left of the
arrow separated by plus signs;
2. Write the names of the products to the right of the
arrow, also separated by plus signs.
1.
Reactant + Reactant Product + Product
EXAMPLE
Methane + Oxygen Carbon dioxide + Water
EXAMPLE 2
Iron + Oxygen Iron(III) Oxide
EXAMPLE 3
Hydrogen Peroxide Water and Oxygen
Skeleton Equations
Write the formulas of the reactants to the left of the yields
sign (arrow) and the formulas of the products to the right.
A skeleton equation is a chemical equation that does not
indicate the relative amounts of the reactants and products.
Here is the equation for rusting:
Fe + O2 Fe2O3
Formula Writing Practice WS
Catalyst
A catalyst is a substance that speeds up the reaction but is
not used up in the reaction
Without catalyst
With Catalyst
Important Symbols
Balancing Chemical Equations
To write a balanced chemical equation,
Write the skeleton equation
2. Use coefficients to balance the equation so that it obeys the law
of conservation of mass.
Remember you want the same number of atoms of each element
on each side of the equation.
1.
Example
Example 2
Example 3 -- Try on your own!!!
Write a balanced chemical equation for the reaction in which
sodium hydroxide and calcium bromide react to produce
solid calcium hydroxide and sodium bromide. (The reaction
occurs in water.)
NaOH(aq)+CaBr2(aq)
Ca(OH)2(s)+NaBr(aq)
2NaOH(aq)+CaBr2(aq)
Ca(OH)2(s)+2NaBr(aq)
Summary
Write a skeleton
equation
Count atoms
Add/adjust
coefficients
Reduce coefficients
to lowest possible
ratio
Check your work
Warm Up!!
_____NaClO3 →____ NaCl + __O2
Chemical Equations from Names
Magnesium and Hydrogen Chloride produce Hydrogen and Magnesium
Chloride
Calcium Hydroxide and Lithium Chloride produce Lithium Hydroxide
and Calcium Chloride
Decompose Copper (II) oxide into Copper and Oxygen
Aluminum and Iron (III) oxide produce iron and aluminum oxide
combustion of Butane (C4H10) in air to produce carbon dioxide and water
Warm Up
___AgNO3 + __Ni __Ni(NO3)2 + __Ag
The Five Types of Reactions
Synthesis
Combustion
Decomposition
Chemical
Reactions
Double
Replacement
Single
Replacement
Chemistry with
Synthesis Reactions
A + B AB
1. Synthesis Reactions
(Combination)
Two or more reactants produce
one product
Examples:
NH3 + HCl
NH4Cl
H2 + O2
H2O
Ag2S
Al + Cl2
AlCl3
Ag + S
Chemistry with
Decomposition Reactions
AB A + B
2. Decomposition
One reactant produces two or
more products
Examples
Ag2O Ag + O2
PCl5 PCl3 + Cl2
H2O2 H2O + O2
CuO Cu +
O2
Chemistry with
Single Replacement
AB + C AC + B
3. Single Replacement
One element replaces another
element
Must consult the activity series
3. Single Replacement
One element and one
compound producing a
different element and
compound
Examples
Fe + H3(PO4) H2 + Fe3(PO4)2
H2 + CuO Cu + H2O
Zn + HCl H2 + ZnCl2
Cl2 + KBr Br2 + KCl
Equations Activity Series Worksheet
Chemistry with
Double Replacement
AB + CD AD + CB
4. Double Replacement
A double-replacement reaction is
a chemical change involving an
exchange of positive ions between
two compounds.
Examples:
Al(NO3)3 + NaOH Al(OH)3
+ NaNO3
PbCl2 + Li2SO4 PbSO4 +
LiCl
ZnBr2 + AgNO3 Zn(NO3)2
+ AgBr
BaCl2 + KIO3 Ba(IO3)2 +
KCl
4. Double replacement
Three main products of a double replacement reaction
Precipitate (solubility table)
Water
Gas
5. Combustion
A combustion reaction
Chemical change
Element or a compound reacts with oxygen
Producing energy in the form of heat and light
5. Combustion
A hydrocarbon reacts with oxygen to produce carbon dioxide
and water
Examples:
CH4 + O2 CO2 + H2O
C6H12O6 + O2 CO2 + H2O