Explanation:
(a) the percent composition of hydrazoic acid, HN₃
The mass of the atoms are as follows -
mass of H = 1 g/mol
mass of N = 14 g/mol
The percentage of H = mass of hydrogen / mass of total compound * 100
The percentage of H = 1 / ( 1 + 3 * 14 ) * 100 = 2.326 %
The percentage of the remaining N = 100 - 2.326 = 97.67 %
( b ) the percent composition of TNT, C₆H₂(CH₃)(NO₂)₃
The mass of the atoms are as follows -
mass of C = 12 g /mol
mass of H = 1 g /mol
mass of N = 14 g /mol
mass of O = 16 g /mol
Molar mass of TNT is 12 (7) + 1 (5) + 14 (3) + 16 (6) = 229 g/mol
The percentage of H = 5 * 1 / 229 = 2.183 %
The percentage of C = 7* 12 / 229 = 36.68 %
The percentage of N = 3 * 14 / 229 = 18.34 %
The percentage of O = 6 * 16 / 229 = 42.78 %
(c) the percent of SO₄²⁻in Al₂(SO₄)₃
The mass of the atoms are as follows -
mass of O = 16 g /mol
mass of S = 32 g/mol
mass of Al = 27 g/mol
The molar mass of SO₄²⁻ = 32 + 4 * 16 = 96 g/mol
The molar mass of Al₂(SO₄)₃ = 342 g /mol
The percentage of SO₄²⁻in Al₂(SO₄)₃ = 96 g/mol / 342 g /mol * 100 =
28.07 % .
