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Stoichiometry

The document outlines the learning outcomes for a lesson on stoichiometry, including the ability to explain stoichiometry, convert between masses and moles, identify limiting and excess reactants, and calculate yields. It describes stoichiometry as the calculation of reactant and product quantities based on balanced chemical equations and provides methods for determining limiting reactants and calculating percent yield. Additionally, it connects stoichiometric calculations with enthalpy changes in chemical reactions.

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Maria Romela Murillo
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46 views10 pages

Stoichiometry

The document outlines the learning outcomes for a lesson on stoichiometry, including the ability to explain stoichiometry, convert between masses and moles, identify limiting and excess reactants, and calculate yields. It describes stoichiometry as the calculation of reactant and product quantities based on balanced chemical equations and provides methods for determining limiting reactants and calculating percent yield. Additionally, it connects stoichiometric calculations with enthalpy changes in chemical reactions.

Uploaded by

Maria Romela Murillo
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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STOICHIOMETRY

LEARNING OUTCOMES

At the end of the lesson, students should be able to:


▪ Explain the meaning of the term "stoichiometry".
▪ Convert from mass or moles of one substance to mass or moles
of another substance in a chemical reaction.
▪ Identify the limiting and excess reactant in a given chemical
reaction.
▪ Calculate percentage or actual yields from known amounts of
reactants.
▪ Relate stoichiometric calculations with enthalpy changes.
STOICHIOMETRY
▪ Stoichiometry is the calculation of the quantities of reactants or
products in a chemical reaction using the relationships found in
a balanced chemical equation.
▪ The coefficients in a balanced chemical equation represent
the reacting ratios of the substances in the reaction.
▪ The coefficients of a balanced equation can be used to
determine the ratio of moles of all substances in the reaction.

2C6H6 + 7O2 → 4CO2 + 6H2O


MOLE TO MASS
CONVERSIONS

▪ To answer stoichiometry
questions in terms of the
masses of a particular
substance, we do this
using the following
sequence:
MASS TO MASS
CONVERSIONS

▪ To answer mass to mass


stoichiometry questions,
we do this using the
following sequence:
LIMITING AND EXCESS REACTANT
▪ Consider this concept now with regard to a chemical process, the reaction
of hydrogen with chlorine to yield hydrogen chloride:

H2 + Cl2(g) → 2HCl(g)

▪ The balanced equation shows that hydrogen and chlorine react in a 1:1
stoichiometric ratio. If these reactants are provided in any other amounts,
one of the reactants will nearly always be entirely consumed, thus limiting the
amount of product that may be generated. This substance is the limiting
reactant, and the other substance is the excess reactant.
LIMITING AND EXCESS REACTANT
Find the limiting reactant by calculating and comparing the amount of product that
each reactant will produce.
1. Balance the chemical equation for the chemical reaction.
2. Convert the given information into moles.
3. Use stoichiometry for each individual reactant to find the mass of product
produced.
4. The reactant that produces a lesser amount of product is the limiting reactant.
5. The reactant that produces a larger amount of product is the excess reactant.
6. To find the amount of remaining excess reactant, subtract the mass of excess
reactant consumed from the total mass of excess reactant given.
PERCENT YIELD
▪ To compute the percent yield, it is first necessary to determine how much of
the product should be formed based on stoichiometry.
▪ This is called the theoretical yield, the maximum amount of product that can
be formed from the given amounts of reactants.
▪ The actual yield is the amount of product that is actually formed when the
reaction is carried out in the laboratory.
▪ The percent yield is the ratio of the actual yield to the theoretical yield,
expressed as a percentage.
STOICHIOMETRIC CALCULATIONS AND
ENTHALPY CHANGES

▪ Enthalpy is the heat content of a system at constant pressure.


▪ The heat that is absorbed or released by a reaction at constant
pressure is the same as the enthalpy change, and is given the
symbol ∆H.
▪ Chemistry problems that involve enthalpy changes can be
solved by techniques similar to stoichiometry problems.
THANK YOU FOR
LISTENING!

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