3.2 Use of amount of substance in relation to masses of pure substances

• Amount of substance is measured in moles
• Molar mass is represented by the symbol M
• Molar mass is measured in grams per mole
• Amount of substance is measured in moles
• What is the symbol for molar mass?

  M
• What is the molar mass of sodium chloride (NaCl)?

  58.44 g/mol
• Calculate the mass of 0.75 moles of sodium chloride (NaCl), with a molar mass of 58.44 g/mol. The answer is 43.83 grams.
• What formula is used to calculate molar mass (M) from mass (m) and moles (n)?

  $M =$$\frac{m}{n}$
• The molar mass of ethanol calculated from 46 grams and 1 mole is 46 g/mol.


  True
• What is the value of Avogadro's constant?

  $6.022 \times 10^{23}$
• Match the quantity with its unit:

  Mass ↔️ grams

  Amount of Substance ↔️ moles
• The formula to calculate moles from mass and molar mass is n = \frac{m}{M}</latex>.


  True
• When 50 grams of NaCl are divided by its molar mass (58.44 g/mol), the number of moles calculated is 0.856.
• What is the mass of 2.5 moles of water (H₂O), given its molar mass is 18.015 g/mol?

  45.0375 g
• What is the molar mass of water (H₂O)?

  18.015 g/mol
• What is the formula to calculate molar mass (M)?

  $M =$$\frac{m}{n}$
• The molar mass of glucose (C₆H₁₂O₆) is 180.16 g/mol.


  True
• One mole contains 6.022 x 10^23 entities.

  True
• The formula to calculate molar mass is m = n × M.


  True
• The formula to calculate moles from mass is n = m/M.


  True
• Amount of substance is measured in moles
• One mole contains 6.022 x 10^23 entities.

  True
• The formula to calculate molar mass is m = n × M

  False
• Calculate the number of moles in 25 grams of carbon dioxide (CO2), given its molar mass is 44.01 g/mol.

  0.568 moles
• What is the molar mass of ethanol (C2H5OH) if 46 grams contains 1 mole?

  46 g/mol
• The unit for mass is grams
• What is the molar mass of a substance if 25 grams contain 0.5 moles?

  50 g/mol
• 3.011 x 10^23 molecules of water correspond to 0.5 moles.


  True
• Molar mass is measured in grams per mole.
• Steps to calculate moles from mass and molar mass

  1️⃣ Identify the mass (m) in grams

  2️⃣ Determine the molar mass (M) in g/mol

  3️⃣ Substitute values into the formula

  4️⃣ Solve for n (moles)
• What formula is used to calculate mass (m) from moles (n) and molar mass (M)?

  $m =$$n \times M$
• The formula to calculate mass from moles is m = n × M
• The mass of 2.5 moles of water is 45.0375 grams.


  True
• Match the quantity with its definition:

  Mass ↔️ The amount of matter in an object

  Moles ↔️ The amount of substance containing 6.022 × 10²³ entities

  Molar Mass ↔️ The mass of one mole of the substance
• The formula to calculate the number of moles (n) is n = m / M
• What is the unit for molar mass?

  grams per mole
• What is Avogadro's constant?

  6.022 x 10^23
• Calculate the number of moles in 25 grams of CO2 (molar mass = 44.01 g/mol).

  0.568 mol
• What is the value of Avogadro's constant?

  6.022 x 10^23
• Molar mass is measured in grams per mole