1.2 Amount of Substance

• What is relative atomic mass (\(A_r\)) defined as?

  Mean mass of an atom divided by one-twelfth of carbon-12's mass
• What is relative molecular mass (\(M_r\)) defined as?

  Mean mass of a molecule divided by one-twelfth of carbon-12's mass
• What term is relative molecular mass known as for ionic compounds?

  Relative formula mass
• What kind of measurement is the mole?

  Unit of measurement for substances
• What does one mole always contain?

  The same number of particles
• What is the Avogadro constant also known as?

  L
• What does the Avogadro Constant allow us to find?

  The number of particles in a sample of known mass
• In the equation linking moles, number of particles and the Avogadro constant, what does 'n' represent?

  Moles
• In the equation linking moles, number of particles and the Avogadro constant, what does 'L' represent?

  Avogadro constant
• What role does the mole play in calculations?

  A very important unit of measurement
• What are the units for concentration in the equation: moles = concentration x volume?

  moldm​-3

  
• Under what conditions do gases and volatile liquids follow certain trends?

  Standard conditions
• According to the text, what is pressure proportional to?

  Temperature
• According to the text, what is volume proportional to?

  Temperature
• According to the text, what are pressure and volume proportional to?

  Inversely proportional
• What is the combination of the relationships between pressure, volume and temperature known as?

  The ideal gas equation
• What are the standard units for pressure in the ideal gas equation?

  Pascals
• What are the standard units for volume in the ideal gas equation?

  m³
• What are the standard units for temperature in the ideal gas equation?

  Kelvin
• In the ideal gas equation, what does 'n' stand for?

  Moles
• In the context of ideal gas equation, what does 'm' represent?

  Mass in grams
• What is the ideal gas constant represented by?

  R

  
• What is the value of the ideal gas constant?

  8.31 JK⁻¹mol⁻¹
• What is the empirical formula defined as?

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

  Using molar ratios of each element
• What is the molecular formula defined as?

  True number of each atom in the molecule
• What values are used to determine molecular formula?

  \(M_r\) of the empirical formula and true \(M_r\)

  
• What is the multiplier value used for?

  Scale up the empirical formula
• Before chemical equations can be used in calculations, what must they be?

  Balanced
• Why must chemical equations be balanced?

  The reacting ratios must be correct
• Once a chemical equation is balanced, what can it be used to calculate?

  Reacting masses, percentage yield, and atom economy
• What is the formula for percentage yield?

  (Actual yield / Theoretical yield) x 100

  
• What is the formula for atom economy?

  (Mass of desired product / Total mass of reactants) x 100
• In industrial chemical processes, is it more desirable to have what kind of atom economy for a reaction?

  High
• What does a high atom economy mean?

  Little or no waste product
• What does a high atom economy indicate about the economic viability of industrial scale manufacture?

  More economically viable
• What does a high atom economy indicate about the resources used by industrial scale manufacture?

  Uses less natural resources
• What impact does a high atom economy have on energy usage?

  Often uses less energy
• Which equation relates moles, number of particles, and the Avogadro constant?

  Number of particles = moles x Avogadro constant
• Which equation relates moles, concentration, and volume?

  Moles = concentration x volume