Question

he compound known as butylated hydroxytoluene, abbreviated as BHT, contains carbon, hydrogen, and oxygen. A 3.376 g sample of BHT was combusted in an oxygen rich environment to produce 10.11 g of CO2(g) and 3.312 g of H2O(g) . Insert subscripts to complete the empirical formula of BHT.

Answer 1

Its empirical formula is the same as it molecular formula - C15H24O.

Step-by-step explanation:

Equation: BHT + O2 → CO2 + H2O

moles of CO2 = mass/ molar mass = 10.11 / (12+16x2) = 0.23 mol

moles of H2O = mass/ molar mass = 3.312 / (1x2+16) = 0.184 mol

The elements are conserved during reaction. BHT is formed from three elements Carbon, Oxygen and Hydrogen.

We have: mass of BHT = mass of Carbon element + mass of Hydrogen element + mass of Oxygen element.

moles of Carbon (in BHT) = moles of CO2 = 0.23 mol.

⟹ mass of Carbon = moles x molar mass = 0.23 x 12 = 2.76 gram

moles of Hydrogen (in BHT) = 2 x moles of H2O = 0.184 x 2 = 0.368 mol

⟹ mass of Hydrogen = 0.368 x 1 = 0.368 gram

⟹ mass of Oxygen (in BHT) = 3.376 -0.368-2.76 = 0.248 gram

⟹ moles of Oxygen (in BHT) = 0.248/32 = 0.0155 mol

Ratio

C : H : O = 0.23 : 0.368 : 0.0155 = 15 : 24 : 1

So the formula of BHT is C15H24O