Calculating Moles of an Element

• What should you be able to calculate by the end of the video?

  The number of moles of an element
• What is the target audience for this topic?

  This topic is for the higher tier only
• What will be covered in the upcoming videos?

  How to use maths to carry out calculations in chemistry
• What does relative atomic mass tell us?

  The mass of a single atom of an element
• How is relative atomic mass calculated?

  From the average masses of the isotopes weighted for their abundance
• Where can relative atomic masses be found?

  On the periodic table
• What is the relative atomic mass of carbon?

  12
• What is the relative atomic mass of oxygen?

  16
• What does the term "mole" refer to in chemistry?

  A very large number
• What is one mole in terms of quantity?

  A shorthand way of saying a specific large number of atoms
• How many grams of carbon correspond to one mole?

  12 grams
• How many grams of oxygen correspond to one mole?

  16 grams
• Why is the mole concept useful in chemistry?

  It allows scientists to calculate how many atoms of a substance they have in a chemical reaction
• What is the equation to calculate the number of moles?

  The number of moles = mass in grams / relative atomic mass
• If you have 48 g of magnesium, how many moles do you have?

  2 moles
• What is the relative atomic mass of magnesium?

  24
• How many moles are in 120 g of calcium with a relative atomic mass of 40?

  3 moles
• How many moles are in 252 g of iron with a relative atomic mass of 56?

  1. 5 moles
• How many moles are in 4,064 g of sulfur with a relative atomic mass of 32?

  127 moles
• What is the process for calculating the number of moles of an element?

  • Identify the mass of the element in grams
  • Find the relative atomic mass from the periodic table
  • Use the formula: Number of moles = mass in grams / relative atomic mass
• What are the key points about relative atomic mass?

  • It tells the mass of a single atom of an element
  • Calculated from average masses of isotopes weighted for abundance
  • Has no units
  • Found on the periodic table
• What are the steps to solve mole calculation problems?

  1. Identify the mass of the substance.
  2. Look up the relative atomic mass.
  3. Apply the formula to find the number of moles.
  4. Check your calculations with examples.