30 Questions
What is the primary requirement for performing stoichiometry calculations?
A balanced equation
What is the definition of a mole in chemistry?
The amount of substance that contains the same number of particles as there are atoms in 12g of carbon-12
What is the role of the limiting reactant in a chemical reaction?
It is the reactant that determines the amount of product formed
What is the relationship between the number of moles of a pure element and its atomic mass?
The number of moles is numerically equal to the atomic mass
What is the purpose of using the mole concept in the laboratory?
To quantify reactants and products
What is the consequence of having excess reactants in a chemical reaction?
The amount of product formed will be limited
What is the term for the reactant that is completely used up in a chemical reaction?
Limiting reagent
What is the main focus of stoichiometry?
Treating chemical equations as consisting of mathematical symbols/entities
What is the term for reactants that are not used up in a chemical reaction?
Excess reagent
What is the purpose of a balanced chemical equation?
To represent an equality, similar to an algebraic equation
What is the process that involves rearrangement of molecular or ionic structure of a substance?
Chemical reaction
What is represented by the arrow in a chemical equation?
The equal sign
What is the mole relationship between CaCO3 and HCl based on the balanced equation?
1mol CaCO3 : 2mol HCl
What is the formula weight of HCl?
36.46 amu
What is the molar mass of HCl?
36.46 g/mol
What is the unit of atomic weight?
atomic mass units (amu)
What is the purpose of mole relationships in stoichiometry?
To convert between moles of different reactants or products
What is the relationship between formula weight and molar mass?
Formula weight and molar mass have the same value, but different units
What is the molar mass of Fe2O3 calculated as?
2 atoms Fe x 55.85 g/mol Fe + 3 atoms O x 16.00 g/mol O
What is the purpose of using molar mass in stoichiometry problems?
To convert between grams and moles of a substance
What is the unit of molar mass?
grams per mole (g/mol)
What is the molar mass of Fe?
55.85 g/mol
What is the mole ratio of Fe2O3 in the sample problem?
5.00 g / 159.7 g/mol
What is the purpose of a balanced chemical equation in stoichiometry?
To specify the mole relationships of the reactants and products
What is the primary purpose of relating the mass of a substance to moles?
To make a conversion factor
What is the correct order of steps in a stoichiometry gram-to-mole calculation?
Identify what is required, write out conversion factors, set up and solve the problem
What is the molar ratio of oxygen to aluminum oxide in the reaction Al + O2 → Al2O3?
2:1
How many moles of oxygen are needed to react with 3.75 grams of ammonia in the reaction NH3 + O2 → NO + H2O?
2.5 moles
What is the purpose of balancing a chemical equation in mole-to-mole calculations?
To ensure the equation is mathematically correct
How many moles of CO are produced from 3.5 moles of C2H6 in the reaction C2H6 + O2 → CO + H2O?
2.5 moles
Understand the quantitative relationships between substances in chemical reactions, including limiting reactants and the amount of products formed. Learn how to treat chemical equations as mathematical symbols and entities in stoichiometry. Test your knowledge of chemical equations and quantitative chemical work.
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