Amount of Substance

• What is relative atomic mass (Ar) defined as?

  Mean mass of an atom divided by carbon-12 mass
• What is relative molecular mass (Mr) defined as?

  Mean mass of a molecule divided by carbon-12 mass
• What is relative formula mass used for?

  For ionic compounds
• What is the mole a unit of?

  Measurement for substances
• What does the Avogadro Constant represent?

  Number of particles in a mole
• How can the number of particles in a sample be found?

  Using the Avogadro Constant
• Why is the mole important in calculations?

  It standardizes measurements of substances
• What is the ideal gas equation used for?

  To describe gas behavior under standard conditions
• What are the relationships between pressure, volume, and temperature of gases?

  Pressure is proportional to temperature
• What must the variables be in for the ideal gas equation?

  Correct standard units
• What is the ideal gas constant (R) value?

  8.31 JK​-1​mol​-1​
• What is an empirical formula?

  Simplest whole number ratio of atoms
• How is the empirical formula found?

  Using molar ratios of each element

  
• What is a molecular formula?

  True number of each atom in a molecule
• How can the molecular formula be determined?

  Using Mr of empirical and true Mr

  
• Why must chemical equations be balanced?

  To ensure correct reacting ratios
• What can balanced equations be used to calculate?

  Reacting masses, percentage yield, atom economy
• What is percentage yield?

  Measure of the efficiency of a reaction

  
• What does high atom economy mean?

  Little or no waste product
• Why is high atom economy beneficial for the environment?

  Uses less natural resources and energy