How many milliliters of water at 20.0 °C are formed in the combustion of 25.0 g of a methanol–propanol mixture that is 62.5% methanol by mass? Assume there is an excess of oxygen available.
To find the number of milliliters of water formed in the combustion of the methanol-propanol mixture, we need to follow these steps:
1. Determine the mass of methanol and propanol in the mixture:
- Given that the mixture is 62.5% methanol by mass and contains 25.0 g of the mixture, we can calculate the mass of methanol as:
Mass of Methanol = 62.5% * 25.0 g
- To find the mass of propanol, we can subtract the mass of methanol from the total mass of the mixture:
Mass of Propanol = Total Mass of Mixture - Mass of Methanol
2. Convert the mass of methanol and propanol to moles:
- Use the respective molar masses of methanol (32.04 g/mol) and propanol (60.10 g/mol) to convert the masses to moles.
3. Identify the balanced chemical equation for the combustion of methanol (CH₃OH):
- The balanced equation for the combustion of methanol is:
CH₃OH + O₂ → CO₂ + H₂O
4. Use the stoichiometry of the balanced equation to find the number of moles of water produced:
- From the balanced equation, we know that one mole of methanol reacts with one mole of water.
- So, the number of moles of water produced is equal to the number of moles of methanol consumed.
5. Convert the moles of water to milliliters:
- Use the molar volume of water (18.02 g/mol) to convert moles of water to milliliters.
Let's calculate:
1. Mass of Methanol = 62.5% * 25.0 g = 15.625 g
Mass of Propanol = 25.0 g - 15.625 g = 9.375 g
2. Moles of Methanol = Mass of Methanol / Molar Mass of Methanol
Moles of Propanol = Mass of Propanol / Molar Mass of Propanol
3. The balanced equation for the combustion of methanol is:
CH₃OH + O₂ → CO₂ + H₂O
4. Number of Moles of Water = Moles of Methanol
5. Milliliters of Water = Number of Moles of Water * MolarVolume of Water
Now, substitute the values, calculate the results, and find how many milliliters of water are formed in the combustion of the given methanol-propanol mixture.