Mr , Ar and the Mole

• What is the formula to calculate the number of moles from mass and Mr/Ar?

  Number of moles = Mass (grams) / Mr or Ar
• How many moles are in 23g of Gold with an Ar of 197?

  0.12 mol
• Why is it important to rearrange the formula for calculating moles?

  To solve for any two known components in the equation
• What is Avogadro's Number?

  1. 6.02 x 10²³
• What does 1 mole of a substance represent in terms of particles?

  It contains 6.02 x 10²³ atoms or molecules
• How many molecules are in 1 mole of H₂O?

  1. 6.02 x 10²³ molecules of H₂O
• How do you calculate the number of particles in a substance?

  Number of particles = Avogadro's Number x Number of Moles
• How many particles are in 0.67 moles of Ammonia (NH₃)?

  1. 6.02 x 10²³ particles
• What is the formula to calculate the number of moles in a solution?

  Number of moles = Concentration (moldm³) × Volume (dm³)
• How many moles are in 200 cm³ of 0.35 moldm³ HCl?

  0.07 mol