Find the volume of air required to burn 25 g of ethanol.

1. Let’s write down the reaction equation:

C2H5OH + 3O2 = 2CO2 + 3H2O.

2. Find the amount of ethanol reacted (Vm – molar volume, constant equal to 22.4 l / mol):

n (C2H5OH) = m (C2H5OH) / M (C2H5OH) = 25 g / 46 g / mol = 0.54 mol.

3. According to the reaction equation, we find the amount, and then the volume of oxygen:

n (O2) = n (C2H5OH) * 3 = 1.63 mol.

V (O2) = n (O2) * Vm = 1.63 mol * 22.4 L / mol = 36.52 L.

4. Find the volume of air required for the reaction:

V (air) = V (O2) * 100% / ω (O2) = 36.52 l * 100% / 21% = 173.91 l.

Answer: V (air) = 173.91 liters.