1.4 Chemical Formulae, Equations, and Calculations

• What does a chemical formula represent?

  Composition of a compound
• What does the chemical formula convey that the chemical name does not?

  Exact elemental composition
• Chemical formulae are written using chemical symbols and subscripts
• Match the compound type with its naming convention:

  Ionic ↔️ Cation + Anion

  Covalent ↔️ Use prefixes
• What does the law of conservation of mass state?

  Mass is neither created nor destroyed
• A chemical formula uses chemical symbols and subscripts
• A balanced chemical equation ensures the number of atoms of each element is equal on both sides.


  True
• The law of conservation of mass states that mass is neither created nor destroyed
• Steps for balancing chemical equations

  1️⃣ Identify reactants and products

  2️⃣ Count the number of atoms of each element

  3️⃣ Adjust the coefficients to balance atoms
• What is the numerical value of Avogadro's number?

  6.022 × 10²³
• The mole represents 6.022 × 10²³ particles, also known as Avogadro's number.
• Molar mass is numerically equal to the atomic or molecular weight in atomic mass units (u).

  True
• A chemical formula uses chemical symbols and subscripts to indicate the number of atoms.
• The chemical formula conveys the exact elemental composition of a substance.


  True
• What is the naming convention for ionic compounds?

  Cation + Anion
• The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.

  True
• A balanced chemical equation ensures the number of atoms of each element is equal on both sides.
• Steps to balance a chemical equation

  1️⃣ Identify the reactants and products

  2️⃣ Count the number of atoms of each element

  3️⃣ Adjust the coefficients to balance the atoms
• The mole represents 6.022 × 10²³ particles, known as Avogadro's number
• Match the stoichiometric steps with their actions:

  Convert to moles ↔️ Use molar mass

  Apply mole ratio ↔️ Use balanced equation

  Convert back ↔️ Convert moles to grams
• What is the balanced equation for the reaction between sodium and chlorine to form sodium chloride?

  2Na + Cl2 → 2NaCl
• Stoichiometry is the quantitative study of the reactants and products in a chemical reaction.
• What is used to convert grams to moles in stoichiometry calculations?

  Molar mass
• Mole ratios are derived from balanced chemical equations.


  True
• What is used to convert moles to the number of particles?

  Avogadro's number
• Stoichiometric calculations rely on balanced chemical equations.


  True
• The first step in stoichiometric calculations is to convert given masses to moles
• Steps for stoichiometry calculations

  1️⃣ Convert to moles

  2️⃣ Apply mole ratio

  3️⃣ Convert back to grams
• What is the balanced equation for the combustion of methane (CH4) with oxygen (O2)?

  CH4 + 2O2 → CO2 + 2H2O
• If you have 10 grams of CH4, you have 0.623 moles of CH4.
• In the balanced equation for methane combustion, what is the mole ratio of CH4 to CO2?

  1:1
• 1 mole of CH4 produces 1 mole of CO2 in the combustion reaction.

  True
• The molar mass of CO2 is 44.01 g/mol.
• The mole ratio of CH4 to H2O in the combustion reaction is 1:2.


  True
• In a chemical formula, subscripts indicate the number of atoms
• The chemical formula for water is H2O.


  True
• What is a balanced chemical equation?

  Equal number of atoms
• A balanced chemical equation ensures the conservation of mass.
• What fundamental law is upheld when balancing chemical equations?

  Conservation of mass
• What does a chemical formula convey about a substance?

  Elemental composition