Stoichiometry

• What is the SI symbol for amount of substance?

  n
• What is the unit for amount of substance?

  Mole (mol)
• Why is the mole considered a unit for counting entities?

  It represents Avogadro's number of entities
• What is Avogadro's number?

  6.022 x 10^23
• Calculate the amount of substance (in mol) if the mass of aspirin is 300 mg and its molecular weight is 180.157 g/mol.

  0.001665 mol
• What is the mass of sodium pertechnetate if the number of entities is 2.5 x 10^12 and its molecular weight is 185.99 g/mol?

  7.72 x 10^-10 g
• What is the relationship between 1 cm^3 and 1 mL?

  1 cm^3 = 1 mL
• What is the typical unit for concentration?

  g dm^-3
• Calculate the molarity of a solution if 1.7753 g of potassium iodate (KIO3) is dissolved in 500.0 mL of water. The molecular weight of KIO3 is 214.001 g/mol.

  0.01659 M
• What is the molarity of a 0.9% m/v solution of sodium chloride?

  0.154 M
• What is the difference between amount of substance and concentration?

  Amount is in moles, concentration is moles per volume
• Calculate the amount of sodium in 10 mL of a 0.1 M sodium sulphate (Na2SO4) solution.

  0.002 mol
• What is the total amount of sodium chloride when 25 mL of 0.30 M and 50 mL of 0.15 M solutions are mixed?

  0.015 mol
• What does a 0.9% m/v solution of sodium chloride mean?

  0.9 g of NaCl per 100 mL of solution
• What is the molecular weight of aspirin (C9H8O4)?

  180.157 g/mol
• Calculate the amount of water in 0.5 mol of sodium sulphate decahydrate (Na2SO4×10H2O).

  5 mol
• What is the significance of Avogadro's number in chemistry?

  It defines the number of entities in one mole
• What is the concentration of a lead nitrate solution if 102.3 mg is dissolved in 250.0 mL of water?

  0.4092 g/L
• What is the relationship between molarity and concentration?

  Molarity is concentration in mol/L
• What is the molecular weight of sodium pertechnetate (NaTcO4)?

  185.99 g/mol
• Calculate the mass of water in 5 mol of H2O if the molecular weight is 18.015 g/mol.

  90.075 g
• What is the difference between mol dm^-3 and mol L^-1?

  They are equivalent units
• What is the molecular weight of potassium iodate (KIO3)?

  214.001 g/mol
• What is the molarity of a solution if 1.7753 g of potassium iodate is dissolved in 500.0 mL of water?

  0.01659 M
• What does the term "amount concentration" refer to?

  Concentration in mol/L
• What is the molecular weight of sodium chloride (NaCl)?

  58.443 g/mol
• Calculate the amount of sodium chloride in 100 mL of a 0.9% m/v solution.

  0.0154 mol
• What is the relationship between 1 dm^3 and 1 L?

  1 dm^3 = 1 L
• What is the molecular weight of water (H2O)?

  18.015 g/mol
• Calculate the mass of sodium pertechnetate if the number of entities is 2.5 x 10^12 and its molecular weight is 185.99 g/mol.

  7.72 x 10^-10 g
• What is the significance of the term "entities" in chemistry?

  It refers to atoms, molecules, ions, or particles
• What is the molecular weight of lead nitrate (Pb(NO3)2)?

  331.2 g/mol
• Calculate the concentration of a lead nitrate solution if 102.3 mg is dissolved in 250.0 mL of water.

  0.4092 g/L
• What is the difference between molarity and molality?

  Molarity is mol/L, molality is mol/kg
• What is the molecular weight of sodium sulphate (Na2SO4)?

  142.04 g/mol
• Calculate the amount of sodium in 10 mL of a 0.1 M sodium sulphate solution.

  0.002 mol
• What is the relationship between 1 L and 1000 cm^3?

  1 L = 1000 cm^3
• What is the molecular weight of sodium chloride (NaCl)?

  58.443 g/mol
• Calculate the amount of sodium chloride in 100 mL of a 0.9% m/v solution.

  0.0154 mol
• What is the relationship between 1 dm^3 and 1 L?

  1 dm^3 = 1 L