Stoichiometry Review Flashcards
Theory questions from the review
What is a conversion factor?
A numerical ratio or fraction used to express a measurement where the units are changed, but not the value.
Why is a conversion factor useful?
It allows us to find different measurements of a substance without changing anything.
What is ‘the mole’?
The amount of substance holding 6.022x10^23 of anything.
What analogy can be used to explain ‘the mole’?
It is like saying ‘dozen,’ where one dozen means twelve of something.
How are relative atomic mass and molar mass related?
Molar mass is equivalent to relative atomic mass.
What is the unit for mass, molar mass, and moles?
Mass: m (g), Molar mass: M (g/mol), Moles: n (mol)
What is the link between amount of substance and moles?
The conversion factor of 6.022x10^23 over 1 mol.
What is the Law of Definite Proportions?
Different samples of the same compound always contain its constituents’ elements in the same proportions by mass.
What is the empirical formula?
The simplest, whole-number ratio of the atoms/ions in the compound.
What is the molecular formula?
The actual number of atoms of each element in one molecule of the compound.
Which formula is more useful to scientists, empirical or molecular?
Molecular formula.
Define stoichiometry.
The study of the quantitative aspects of chemical reactions.
What is critical before starting any stoichiometry problem?
The chemical equation must be balanced.
What is a limiting reagent?
A reactant that reacts completely and is not present when the reaction is complete.
What is an excess reagent?
Any reactant that is leftover at the end of a reaction.
What analogy can be used to compare limiting and excess reagents?
Like having ingredients for making a burger, where the limiting reagent is the ingredient that runs out first.
What is the difference between theoretical yield and actual yield?
Theoretical yield is the estimated mass of product obtained, while actual yield is the mass obtained from the experiment.
What are some reasons percent yield may be more or less than 100%?
1) The Nature of the Reaction 2) Experiment Procedure 3) Impurities 4) Competing Side Reactions
Why is determining the yield of a chemical reaction important in the chemical industry?
It is crucial for process effectiveness, product quality, safety, and economic viability.
