Chem.: Ch. 8: SG

Stiochiometry

Describes mass relationships between reactants and products in a chemical equation

A conversion factor that releases the moles of any two substances in a BALANCED chemical equation, describes the relationship between 2 reactants, 2 products, or 1 reactant and 1 product

Mole ratio and what it describes

To convert from moles of 1 substance to moles of a different substance

Use of mole ratio

Coefficients in front of each substance

Used to create a mole ratio

The relative number of moles of reactants and products

What coefficients in a chemical equation represent

A mole ratio

What you need to solve EVERY stoichiometry problem

Chemical equations and the law of conservation of mass

Two things stoichiometry is based on

Moles to moles, moles to grams, grams to grams

The 3 types of conversions in stoichiometry problems

Grams to grams

Stoichiometry problem that involves the most steps to solve

Moles to moles

Stoichiometry problem that involves the least steps to solve

The number of sig figs of any measured quantity in the problem

What determines the number of sig figs

mole ratio

What you can use to convert between moles of 1 substance and moles of another substance

Molar mass

What you can use to convert between moles of a substance and grams of the same substance

Limiting Reactant

the reactant the limits the amount of product that can be made, reactant that is completely used up in the reaction which makes the reaction stop; controls the amount of product

Excess reactant

reactant that was not completely used up during the reaction, some of this reactant is left over after the reaction has stopped

Theoretical yield

the maximum amount of product that can be made, determined from the limiting reactant

Actual yield

the measured amount of product formed during a reaction, will be less than the theoretical yield

perform an experiment

How to determine the actual yield

actual yield/theoretical yield x 100

How to calculate percentage yield

Percentage yield

expressed the efficiency of a chemical equation

because the reactants may contain impurities and competing side reactions; Side reactions that compete with the main reaction, impurities in the reactants, it is also affected by the initial amounts of the reactants

Why is actual yield typically smaller in value & possible causes for this

In a perfect world the theoretical yield is the maximum amount of product that can be made

Compare values of theoretical and actual yield & why this would occur