Solving for Reactant using chemical equation

Question

Wine goes bad soon after opening because the ethanol CH3CH2OH in it reacts with oxygen gas O2 from the air to form water H20 and acetic acid CH3COOH the main ingredient of vinegar. What mass of oxygen gas is consumed by the reaction of 1.99 g of ethanol?

Answer 1

CH₃CH₂OH + O₂ ==> CH₃COOH + H₂O (NOTE: This is actually a simplified equation, as this isn't exactly the mechanism for oxidation of ethanol)

moles ethanol present = 1.99 g x 1 mole/46.07 g = 0.043195 moles

moles O₂ needed = 0.043195 moles ethanol x 1 mole O₂/mole ethanol = 0.043195 moles O₂

Mass of O₂ needed = 0.043195 moles O₂ x 32.0 g/mole = 1.3822 g O₂ = 1.38 g (to 2 significant figures)