Question

In an oxyacetylene welding torch, acetylene (C2H2) burns in pure oxygen with a very hot flame. The reaction is: 2 C2H2 + 5 O2 → 4 CO2 + 2 H2O.
What is the mass of CO2 that is produced if 10.0 grams of oxygen completely reacts?

Answer 1

To determine the mass of CO2 produced, we need to calculate the stoichiometry of the reaction.

From the balanced chemical equation, we see that the mole ratio between oxygen and carbon dioxide is 5:4. This means that for every 5 moles of oxygen that react, we will produce 4 moles of carbon dioxide.

First, we need to find the number of moles of oxygen in 10.0 grams of O2:

molar mass of O2 = 16.00 g/mol
moles of O2 = mass / molar mass = 10.0 g / 32.00 g/mol = 0.3125 mol

According to the stoichiometry of the reaction, this amount of oxygen will produce:

moles of CO2 = moles of O2 x (4/5) = 0.3125 mol x (4/5) = 0.25 mol

Finally, we can find the mass of CO2 produced:

molar mass of CO2 = 44.01 g/mol
mass of CO2 = moles of CO2 x molar mass = 0.25 mol x 44.01 g/mol = 11.0 grams

Therefore, 10.0 grams of oxygen will produce 11.0 grams of carbon dioxide.