We can write the following chemical equation:
As you can notice, this reaction is balanced since the number of atoms of each element before and after the reaction occurs is the same.
Now, we're given that 4.61g of Oxygen reacts, and we're asked to find the mass of ethanol that is consumed.
For this, the first thing we need to do is to express the amount in grams into moles: (Dividing by its molar mass)
Now, using the coefficients of the reaction, we know that per each one mol of Oxygen, one mole of ethanol is consumed:
Finally, we express the last amount in moles into grams. (To do this we multiply by the molar mass of ethanol):
Therefore, 6.64 grams of ethanol are consumed.
