4.5 Stoichiometry

• What is the primary focus of stoichiometry in chemistry?

  Quantitative relationships
• Stoichiometry utilizes the balanced chemical equation to determine the moles of reactants needed to produce a certain amount of products
• What are the units for molar mass?

  Grams per mole
• Stoichiometry studies the quantitative relationships between reactants and products in chemical reactions.


  True
• A balanced chemical equation ensures that the number of atoms for each element is the same on both sides.


  True
• Steps to balance a chemical equation

  1️⃣ Write the unbalanced equation

  2️⃣ Count atoms of each element on both sides

  3️⃣ Balance elements one at a time

  4️⃣ Check that all elements are balanced
• Steps to calculate molar mass

  1️⃣ Identify the elements in the compound and their atomic masses

  2️⃣ Multiply each atomic mass by its subscript in the formula

  3️⃣ Add up all the individual masses
• To convert moles to grams, the formula used is mass = moles × molar mass.
• What formula is used to convert grams to moles?

  moles = mass / molar mass
• The molar mass of HCl is 36.5 g/mol.
• In the reaction 2Al + 3Cl₂ → 2AlCl₃, what is the limiting reactant if we start with 10 grams of aluminum and 15 grams of chlorine?

  Chlorine
• A balanced chemical equation ensures that the number of atoms for each element is equal on both sides of the reaction.


  True
• Steps for balancing chemical equations

  1️⃣ Write the unbalanced equation

  2️⃣ Count atoms of each element on both sides

  3️⃣ Balance elements one at a time

  4️⃣ Check that all elements are balanced
• What must you multiply the atomic mass of each element by in the compound formula to calculate molar mass?

  Its subscript
• Stoichiometry uses the balanced chemical equation to determine the molar amounts of reactants needed to produce products.
• In the reaction 2H₂ + O₂ → 2H₂O, 1 mole of O₂ produces 2 moles of H₂O.
• Molar mass is measured in grams per mole (g/mol).
• What formula is used to convert grams to moles?

  moles = mass / molar mass
• How is the limiting reactant identified in a chemical reaction?

  Smallest moles after division
• What formula is used to convert moles to grams?

  mass = moles × molar mass
• Steps to identify the limiting reactant

  1️⃣ Convert masses of reactants to moles

  2️⃣ Divide the moles of each reactant by its coefficient in the balanced equation

  3️⃣ The reactant with the smallest value is the limiting reactant
• Steps to calculate the theoretical yield

  1️⃣ Balance the chemical equation

  2️⃣ Identify the limiting reactant

  3️⃣ Convert moles of limiting reactant to moles of product using the stoichiometric ratio

  4️⃣ Convert moles of product to grams using its molar mass
• Balancing chemical equations ensures the number of atoms for each element is the same on both sides.


  True
• What information is needed from the periodic table to calculate molar mass?

  Atomic masses
• What is the unit for molar mass?

  g/mol
• To convert moles to grams, multiply the number of moles by the molar mass
• Steps to identify the limiting reactant

  1️⃣ Convert reactant masses to moles

  2️⃣ Divide moles by their coefficients

  3️⃣ The smallest value indicates the limiting reactant
• Steps to calculate theoretical yield

  1️⃣ Balance the chemical equation

  2️⃣ Identify the limiting reactant

  3️⃣ Convert moles of limiting reactant to moles of product

  4️⃣ Convert moles of product to grams
• What is the formula for percent yield?

  Percent Yield = (Actual Yield / Theoretical Yield) × 100
• Stoichiometry uses the balanced chemical equation to determine the moles of reactants needed to produce a certain amount of products
• Why is a balanced chemical equation essential for stoichiometric calculations?

  Ensures atomic equality
• Molar mass is the mass of one mole
• What is the branch of chemistry that studies the quantitative relationships between reactants and products in a chemical reaction?

  Stoichiometry
• In the reaction 2H₂ + O₂ → 2H₂O, what is the molar ratio of H₂ to H₂O?

  2:2
• What is the balanced equation for the reaction where hydrogen and oxygen combine to form water?

  2H₂ + O₂ → 2H₂O
• The total molar mass of water (H₂O) is approximately 18.02 g/mol.


  True
• The limiting reactant is the substance that is fully consumed first in a chemical reaction.

  True
• The molar mass of NaOH is 40 g/mol.
• The limiting reactant determines the maximum amount of product formed in a reaction.


  True
• The theoretical yield assumes no product is lost during a reaction.


  True