About 553.6 grams of oxygen are used in this combustion. Explanation: Molecular mass of acetylene: 2 ⋅ M M C + 2 ⋅ M M H
M M C = Molecular mass of carbon M M H = Molecular mass of hydrogen So, 2 ⋅ 12 + 2 ⋅ 1 = 26 grams/mole Mass used in combustion molecular mass = moles used in combustion 180 grams 26 grams mole = 6.92 moles According to the main equation, to 2 moles of acetylene, 5 moles of oxygen are used. M M O = 2 ⋅ 16 = 32 grams/mole So, if we use 6.92 moles of Acetylene, x moles of oxygen will be necessary. x = 6.92 ⋅ 5 2 = 3.46 ⋅ 5 = 17.3 moles of oxygen. 17.3 moles ⋅ 32 grams mole = 553.6 grams of oxygen
