3.2.2 Calculating moles from masses and vice versa

• What is a mole in chemistry?

  A unit to count atoms or molecules
• What are the molar masses of common substances?

  • Oxygen (O₂): 32 g/mol
  • Carbon Dioxide (CO₂): 44 g/mol
  • Water (H₂O): 18 g/mol
• What is Avogadro's constant?

  6.022 x 10²³ particles
• What does a mole represent in terms of particles?

  • 1 mole = 6.022 x 10²³ particles
  • Used for counting atoms and molecules
• How is molar mass measured?

  In grams per mole (g/mol)
• What is the definition of molar mass?

  The mass of one mole of a substance
• If you have 1 mole of carbon atoms, how many carbon atoms do you have?

  6.022 x 10²³ carbon atoms
• If you have 2 moles of a substance, what is the first step to find its mass?

  Identify the given moles (n)
• How do you find a substance's molar mass?

  Look it up on the periodic table
• How do you calculate the mass of 2 moles of carbon dioxide (CO₂)?

  m = 2 x 44 = 88 grams
• How is molar mass similar to a dozen eggs?

  It represents the total mass of a set quantity
• What does the symbol 'm' represent in the formula n = m / M?

  Mass of the substance in grams
• How do you calculate the number of moles from mass for water?

  • Use the formula: n = m / M
  • Given mass (m) = 36 grams
  • Molar mass (M) of water (H₂O) = 18 g/mol
  • Calculation: n = 36 / 18 = 2 moles
• How do you calculate the mass from moles for carbon dioxide?

  • Use the formula: m = n x M
  • Given moles (n) = 1 mole
  • Molar mass (M) of carbon dioxide (CO₂) = 44 g/mol
  • Calculation: m = 1 x 44 = 44 grams
• What are the steps to find the mass of a substance from moles?

  1. Identify the given moles (n)
  2. Find the molar mass (M)
  3. Calculate mass (m) using m = n x M
• How does a mole compare to a dozen?

  Both are units for counting items
• What does the variable 'n' represent in the formula?

  Number of moles
• Why is the concept of a mole useful in chemistry?

  It simplifies working with large numbers of particles
• What is the mass of 2 moles of carbon dioxide (CO₂)?

  88 grams
• What does the variable 'M' represent in the formula?

  Molar mass
• What does the variable 'm' represent in the formula?

  Mass in grams
• How is the molar mass of water calculated?

  Add atomic masses of two hydrogens and one oxygen
• What is the first step in solving mole-mass calculations?

  Identify the given values
• What is the molar mass of water (H₂O)?

  18 g/mol
• What does the symbol 'n' represent in the formula n = m / M?

  Number of moles of the substance
• Why is it important to find the molar mass in mole-mass calculations?

  It is needed to convert between mass and moles
• What does the symbol 'M' represent in the formula n = m / M?

  Molar mass of the substance in g/mol
• How many moles are in 48 grams of oxygen (O₂)?

  1.5 moles
• If you have 10 moles of a substance with a molar mass of 18 g/mol, what is the mass?

  $180 \text{ g}$
• Why is molar mass important in chemistry?

  It relates mass to the number of moles
• What do the symbols n, m, and M represent in mole-mass calculations?

  • n: Moles (mol)
  • m: Mass (g)
  • M: Molar Mass (g/mol)
• How do you calculate the number of moles from mass using the formula?

  Use the formula $n =$$m / M$
• How does molar mass facilitate chemical calculations?

  By converting mass to moles for reactions
• What is the formula to find mass from moles?

  m = n x M
• What is the molar mass of oxygen (O₂)?

  32 g/mol
• What is the formula for converting between moles and mass?

  n = m / M