Polyvinyl chloride (PVC) is a common material used in plastics. Combustion of it
ID: 713094 • Letter: P
Question
Polyvinyl chloride (PVC) is a common material used in plastics. Combustion of its main constituent, vinyl chloride (C2H3Cl), results in the release of toxic HCl vapor (as well as carbon dioxide and water).
2 C2H3Cl(s) + 5 O2(g) 4 CO2(g) + 4 H20(g) + 4 HCl(g)
a) If 114 g of vinyl chloride are combusted in the presence of 125 g of oxygen, how many grams of HCl are formed? g
b) Which is the limiting reactant for the reaction in part (a)?
c) If the HCl vapor produced in part (a) is separated from the other gases and is collected over water at a temperature of 20.0 °C and a pressure of 755 torr, what volume of HCl gas is collected? (the partial pressure of H2O at 20.0 °C is 17.5 torr)
Explanation / Answer
a) moles vinyl chloride = 114 g/62.5 g/mol = 1.824 mol
moles O2 = 125 g/32 g/mol = 3.910 mol
grams HCl produced = 3.910 mol x 4 x 36.5 g/mol/5 = 114.172 g
b) Since moles of O2 available is less than needed for complete combustion of 1.824 mol vinyl chloride.
limiting reactant = O2
c) Pressure of HCl collected (P) = (755 torr - 17.5 torr)/760 = 0.97 atm
T = 293 K
moles HCl (n) = 3.910 mol x 4/5 = 3.128 mol
R = gas constant
using Ideal gas equation,
Volume of HCl collected (V) = nRT/P
= 3.128 x 0.08205 x 293/0.97
= 77.525 L