Quantitative chemistry

• What are isotopes?

  Versions of the same element with different neutrons
• What is the similarity between isotopes of lithium?

  They have the same number of protons

  
• What is the difference between isotopes of lithium?

  They have different numbers of neutrons

  
• How do you calculate the relative atomic mass of lithium with 8% $^{6}Li$ and 92% $^{7}Li$?


  Relative atomic mass = $(0.08 \times 6) +$$(0.92 \times 7)$
• What is the relative atomic mass (Ar)?

  Weighted average mass of an element
• What is the relative atomic mass of sodium (Na)?

  23

  
• What is the relative atomic mass of copper (Cu)?

  63.5
• What is the relative atomic mass of iodine (I)?

  127
• What is the relative formula mass (Mr)?

  Sum of relative atomic masses in a formula
• How do you calculate the relative formula mass (Mr) of Na2O?

  • There are 2 sodium atoms (Na)
  • 1 oxygen atom (O)
  • Calculation: $Mr =$$(2 \times 23) +$$(1 \times 16) =$$62$

  
• What is the Mr of calcium carbonate (CaCO3)?

  $100$
• What is the Mr of sodium carbonate (Na2CO3)?

  $106$
• What is the Mr of lithium nitride (Li3N)?

  $34$
• What is the Mr of hydrogen peroxide (H2O2)?

  $34$
• What is the Mr of nitric acid (HNO3)?

  $63$
• What is the Mr of oxygen (O2)?

  $32$
• What is the Mr of aluminum hydroxide (Al(OH)3)?

  $78$
• What is the formula to calculate percentage by mass of an element in a compound?

  Percentage mass = $(Ar \times \text{no. of atoms}) / Mr \times 100$
• What is the percentage mass of hydrogen (H) in hydrochloric acid (HCl)?

  Calculate using the formula
• What is the percentage mass of aluminum (Al) in aluminum oxide (Al2O3)?

  Calculate using the formula

  
• What is the percentage mass of oxygen (O) in copper hydroxide (Cu(OH)2)?

  Calculate using the formula

  
• What does the term "mole" mean in Latin?

  Mass
• What is Avogadro's Constant?

  6.02 x $10^{23}$
• How do you calculate the number of moles?

  Using the equation: moles = mass / Mr
• How many moles are in 90 g of H2O?

  5 moles
• How many moles are in 20 g of C4H10?

  0.34 moles
• How many moles are in 685 g of NH3?

  40.41 moles
• How many moles are in 102 g of O2?

  3.19 moles
• How many moles are in 2 kg of Al2O3?

  19.6 moles
• How many moles are in 3 kg of Au?

  0.15 moles
• What does the law of conservation of mass state?

  Mass cannot be created or destroyed
• What is the equation that links mass and moles?

  mass = moles x Mr

  
• What is the Mr of zinc hydroxide (Zn(OH)2)?

  99
• What are reacting mass calculations?

  Calculations based on conservation of mass
• What is the significance of limiting reagents in reactions?

  They determine the maximum yield of products
• How do you calculate the percentage yield of a reaction?

  Percentage yield = (actual yield / theoretical yield) x 100

  
• What is the percentage yield if 20.0 g of CaCO3 produces 10.0 g of CaO with a theoretical yield of 11.2 g?

  89.3%
• What is the percentage yield of iron if 80.0 g of Fe2O3 produces 45.0 g of iron with a theoretical yield of 55.8 g?

  80.8%
• What is the percentage yield of ethanol if 180 g of glucose produces 75 g of ethanol with a theoretical yield of 92 g?

  81.5%
• What is atom economy?

  Measure of the efficiency of a reaction