Question

Use the periodic table to calculate the molar mass of each compound below. Give your answer to the correct number of significant figures.

Sodium hydroxide (NaOH):
g/mol
Water (H2O):
g/mol
Glucose (C6H12O6):
g/mol
Calcium sulfate (CaSO4):
g/mol
Magnesium phosphate (Mg3(PO4)2):
g/mol

Answer 1

Answer:

Sodium hydroxide (NaOH):  40.00 g/mol

Water (H2O):  18  ⇒ 18.02 g/mol

Glucose (C6H12O6):  180 ⇒ 180.18 g/mol

Calcium sulfate (CaSO4):  136  ⇒ 136.15 g/mol

Magnesium phosphate (Mg3(PO4)2):  298  ⇒ 262.87 g/mol

Explanation:

Answer 2

The molar mass of the compounds are calculated below:

Sodium Hydroxide:

• The gram molar mass of Sodium = 22.98g/mol
• The gram molar mass of Oxygen = 15.99g/mol
• The gram molar mass of Hydrogen = 1g/mol
• The molecular mass of NaOH = 22.98 + 15.99 + 1 = 39.97g/mol

Water:

• The gram molar mass of Oxygen = 15.99g/mol
• The gram molar mass of Hydrogen = 1g/mol
• The molecular mass of H₂O = 2 X 1 + 15.99 = 17.99g/mol

Glucose:

• The gram molecular mass of carbon = 12g/mol
• The molecular mass of C₆H₁₂O₆ = 6 X 12 + 12 X 1 + 6 X 15.99 = 180.15g/mol

Calcium sulfate:

• The gram molar mass of Calcium= 40g/mol
• The gram molar mass of Oxygen = 15.99g/mol
• The gram molar mass of Sulfur = 32g/mol
• The molecular mass of CaSO₄ = 40+ 4 X 15.99+ 32 = 136.14g/mol

Magnesium phosphate:

• The gram molecular mass of magnesium =24.30 g/mol
• The gram molecular mass of phophorus= 30.97g/mol
• The molecular mass of Mg₃(PO₄)₂ = 3 X 24.30 + 2 X 30.97 + 8 X 15.99 = 262.85g/mol