Answer to Question #165031 in Organic Chemistry for Joma Avila

Question

Calculate the molar mass of the following compounds. Show your work.

Water, H2O 

carbon dioxide, CO2 

sodium chloride, NaCl 

calcium hydroxide, Ca(OH)2 

potassium permanganate, KMnO4

Answer 1

Solution:

M - molar mass

A_r - standard atomic weight

1) Water, H₂O:

M(H₂O) = 2×A_r(H) + A_r(O) = 2×1.00784 + 15.999 = 18.01468 = 18.015

M(H₂O) = 18.015 g/mol

2) Carbon dioxide, CO₂:

M(CO₂) = A_r(C) + 2×A_r(O) = 12.0107 + 2×15.999 = 44.0087 = 44.009

M(CO₂) = 44.009 g/mol

3) Sodium chloride, NaCl:

M(NaCl) = A_r(Na) + A_r(Cl) = 22.9898 + 35.453 = 58.4428 = 58.443

M(NaCl) = 58.443 g/mol

4) Calcium hydroxide, Ca(OH)₂:

Ca(OH)₂ = CaO₂H₂

M(Ca(OH)₂) = A_r(Ca) + 2×A_r(O) + 2×A_r(H) = 40.078 + 2×15.999 + 2×1.00784 = 74.092

M(Ca(OH)₂) = 74.092 g/mol

5) Potassium permanganate, KMnO₄:

M(KMnO₄) = A_r(K) + A_r(Mn) + 4×A_r(O) = 39.0983 + 54.938 + 4×15.999 = 158.032

M(KMnO₄) = 158.032 g/mol