1) Answer is: the formula is C₇N₃O₆H₅.
M(TNT) = 0.150 g; mass of the trinitrotoluene.
ω(N) = 18.5% ÷ 100%.
ω(N) = 0.185; mass percentage of the nitrogen.
m(N) = 0.150 g · 0.185.
m(N) = 0.02775 ·; mass of the nitrogen.
n(N) = 0.02775 g ÷ 14 g/mol.
n(N) = 0.002 mol; amount of the nitrogen.
n(CO₂) = 0.204 g ÷ 44 g/mol.
n(CO₂) = 0.0046 mol.
n(C) = n(CO₂) = 0.0046 mol; amount of the carbon.
m(C) = 0.0046 mol · 12 g/mol.
m(C) = 0.0552 g; mass of the carbon.
n(H₂O) = 0.030 g ÷ 18 g/mol.
n(H₂O) = 0.00166 mol.
n(H) = 2 · n(H₂O) = 0.0033 mol; amount of the hydrogen.
m(H) = 0.0033 mol · 1 g/mol.
m(H) = 0.0033 g; mass of the hydrogen.
2) m(O) = m(TNT) - m(N) - m(C) - m(H).
m(O) = 0.150 g - 0.02775 g - 0.0552 g - 0.0033 g.
m(O) = 0.06375 g.
n(O) = 0.06375 g ÷ 16 g/mol.
n(O) = 0.004 mol; amount of oxygen.
n(C) : n(N) : n(O) : n(H) = 0.0046 mol : 0.002 mol : 0.004 mol : 0.0033 mol.
n(C) : n(N) : n(O) : n(H) = 2.33 : 1 : 2 : 1.66 /×3.
n(C) : n(N) : n(O) : n(H) = 7 : 3 : 6 : 5.
