CHEMICAL
SCIENCE, TECHNOLOGY,
ENGINEERING, AND
12
MATEMATICS
EQUATIONS
Stoichiometry
Nestor Oliveros Jr.
SPST-I
MELC.
1. Calculate the mass of a given number
of moles of an element or compound or
vice versa STEM_gc11s-ie29.
2.Write equations for chemical reactions
and balance the equations
STEM_GC11CR-If-g-34
Objectives
1. Apply the symbols of a
chemical reaction.
2. Demonstrate how to write
chemical equations and
Review
What is
Stoichiometry ?
Review
Review
What is a
mole?
Review
The mole is one of the base
units of the SI, and has the unit
symbol mol.This number is
expressed by the Avogadro
constant, which has a value of
6.02214076 × 1023
Amedeo Avogadro, the
constant's namesake
Review
10 + 70 + 20 = 90
3Fe(s) + 2O₂(g) = FeO (s) • Fe₂O₃(s)
ACTIVITY :
Identify the missing
element of compound
ACTIVITY :
Identify the missing element or
compound.
? + Cl → NaCl
ACTIVITY :
Identify the missing element or
compound.
? + Be → BeO
ACTIVITY :
Identify the missing element or
compound.
C + ? → CH4
ACTIVITY :
Identify the missing element or
compound.
2H2 + ? → 2H2O
ACTIVITY :
Identify the missing element or
compound.
2Ca + ? → 2CaO
ACTIVITY :
Identify the missing element or
compound.
H2 + Cl2 → ?
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A chemical equation is a
shorthand notation to describe 2H2 + O2
a chemical reaction.
→ 2H2O
-Just like a chemical formula,
a chemical equation expresses
quantitative relations.
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Chemical reactions are the processes by
which chemicals interact to form new
chemicals with different compositions.
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Hydrogen and oxygen can make water or hydrogen peroxide
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Anatomy of a Chemical Equation
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SYSMBOLS MEANING
USED
Read as plus or
+ and; Used between
two formulas to
indicate reactants
combined or
products formed
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SYSMBOLS MEANING
USED
→ Read as yields or
produces; Used to
separate ( on the left)
from products (on the
right). The arrow head
points in the direction
of change.
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SYSMBOLS MEANING
USED
Reads as solid;
(s) Written after a
symbol or formula
to indicate that the
physical state of
the substance is
solid.
H2O(s)
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SYSMBOLS MEANING
USED
Read as liquid;
(l) Written after a
symbol or formula
to indicate that the
physical state of
the substance is H2O(l)
liquid.
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SYSMBOLS MEANING
USED
Read as gas;
(g) Written after a
symbol or formula
to indicate that the
physical state of
the substance is H2O(g)
gas.
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SYSMBOLS MEANING
USED
Read as aqueous;
(aq) Written after a
symbol or formula
to indicate that the
substance is
dissolved in water.
2NaOH (aq)
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SYSMBOLS MEANING
USED
∆
Indicates that
reactants must
be heated.
∆
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SYSMBOLS USED MEANING
Indicates that the
reaction is irreversible.
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SYSMBOLS MEANING
USED
N. R. Read as no
reaction; Indicates
that the given
reactants do not
react with each
other
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Anatomy of a Chemical Equation
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1. two molecules of butane react with thirteen
molecules of oxygen, they produce eight molecules
of carbon dioxide and ten molecules of water.
2. In this equation, chlorine gas reacts with two moles
of sodium iodide in aqueous solution, resulting in
the production of solid iodine and two moles of
sodium chloride in aqueous form.
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1. two molecules of butane react with thirteen
molecules of oxygen, they produce eight molecules
of carbon dioxide and ten molecules of water.
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2. In this equation, chlorine gas reacts with two moles
of sodium iodide in aqueous solution, resulting in the
production of solid iodine and two moles of sodium
chloride in aqueous form.
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2. In this equation, chlorine gas reacts with two moles
of sodium iodide in aqueous solution, resulting in the
production of solid iodine and two moles of sodium
chloride in aqueous form.
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Anatomy of a Chemical Equation
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Anatomy of a Chemical Equation
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Anatomy of a Chemical Equation
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This equation represents
the reaction that takes
place when sodium metal
is placed in water.
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This equation represents the reaction that takes place
when sodium metal is placed in water. The solid
sodium reacts with liquid water to produce molecular
hydrogen gas and the ionic compound sodium
hydroxide (a solid in pure form, but readily dissolved
in water).
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Calcium Carbonate Calcium oxide carbon dioxide
Special conditions necessary for a reaction are
sometimes designated by writing a word or symbol
above or below the equation’s arrow. For example, a
reaction carried out by heating may be indicated by
the uppercase Greek letter delta (Δ) over the arrow.
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What is the Chemical
Equation of this
chemical reaction ?
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Stand back and don’t
look at the chemical
reaction to long.
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Anatomy of a Chemical Equation
Magnesium + oxygen → ?
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Anatomy of a Chemical Equation
Magnesium + oxygen → magnesium oxide
(Δ)
2Mg(s) + O2(g) → 2MgO(s)
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stoichiometric ratio: The ratio of the
coefficients of the products and reactants
in a balanced reaction.
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Activity : CHEMICAL EQUATIONS
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How to find the stochiometric ratio of
the chemical reaction.
To find the formula of magnesium oxide,
students will need the mass of the magnesium
and the mass of the oxygen. They will also require
the relative atomic masses.
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To find the formula of magnesium oxide,
students will need the mass of the magnesium
and the mass of the oxygen. We will also require
the relative atomic masses.
Mass Atomic Mass
Mg: Mg: 24 amu
MgO: O: 16 amu
O:
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We then should divide mass by the atomic mass
for each element. This gives the number of
moles of each.
Number moles Mg =
___/24 amu =
Number moles O =
___/16 amu =
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• Having done this for both elements, they
should find the ratio between the two by
dividing them both by the smallest number.
• The ratio should be close to 1:1 as the
formula of magnesium oxide is MgO.
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• Having done this for both elements, they
should find the ratio between the two by
dividing them both by the smallest number.
• The ratio should be close to 1:1 as the
formula of magnesium oxide is MgO.
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Why is Stoichiometric ratios Important?
You can't understand chemistry without
grasping the basics of stoichiometry because
it helps you predict how much of a reactant
participates in a chemical reaction, how much
product you'll get, and how much reactant
might be left over.
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In daily life, concepts
related to
stoichiometric ratios,
chemical equations,
and reactions find
practical applications
in various activities.
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One notable example is
in cooking, where
stoichiometry comes
into play when adjusting
recipes based on serving
sizes.
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Activity :
Show the chemical equation and
calculate the ratio of the
compound after a chemical
reaction.
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Given:
Zn : 4.67g
2HCL :161g
ZnCl2 :168.81
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Zinc reacts rapidly with hydrochloric acid to
form zinc chloride and hydrogen gas. It is a
single displacement reaction where zinc metal
displaces the hydrogen to form hydrogen gas
and zinc chloride.
Zn(s) + 2HCl(aq)→ ZnCl2(aq) + H2(g)
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For further explanation and example of stoichiometric
ratios
Please watch the following YouTube channel.
https://www.youtube.com/watch?v=vITcDWX0jTU&
list=WL&index=9&t=374s
