Certain race cars use methanol (CH 3 OH; also called wood alcohol) as a fuel. Me
ID: 890083 • Letter: C
Question
Certain race cars use methanol (CH3OH; also called wood alcohol) as a fuel. Methanol has a molecular mass of 32.0 g/mol and a density of 0.79 g/mL. The combustion of methanol occurs according to the following equation:
2CH3OH + 3O2 2CO2 + 4H2O
In a particular reaction 2.00 L of methanol are reacted with 80.0 kg of oxygen.
a.What is the limiting reactant?
b.What reactant and how many grams of it are left over?
c.How many grams of carbon dioxide is produced?
Honestly I am at a total loss on what to do.
Explanation / Answer
Certain race cars use methanol (CH3OH; also called wood alcohol) as a fuel. Methanol has a molecular mass of 32.0 g/mol and a density of 0.79 g/mL. The combustion of methanol occurs according to the following equation:
2CH3OH + 3O2 2CO2 + 4H2O
In a particular reaction 2.00 L of methanol are reacted with 80.0 kg of oxygen.
Solution :-
Lets calculate the mass of the methanol using the volume and density
2.00 L * 1000 ml / 1 L = 2000 ml
Mass = volume * density
= 2000 ml * 0.79 g /ml
Now lets calculate the moles of the methanol and O2
Moles = mass / molar mass
Moles of methanol = 1580 g methanol /32.0 g per mol
= 49.375 mol methanol
Moles of O2 = (80.0 kg * 1000 g / 1 kg)*(1 mol O2/ 32 g ) = 2500 mol O2
Now lets calculate the moles of O2 needed to react with 49.375 mol methanol
Mole ratio is 2 mole methanol = 3 mol O2
49.375 mol methanol * 3 mol O 2 / 2 mol methanol = 74.0625 mol O2
Moles of O2 are more than needed for the reaction
Therefore methanol is the limiting reactant
Moles of O2 remain after reaction = 2500 mol – 74.0625 mol = 2425.9375 mol O2
Mass of O2 remain after reaction is
Mass of O2 remain = (2425.9375 mol * 32 g) =77630 g O2
Now lets calculate the mass of CO2 produced
Mole ratio of the methanol to CO2 is 2:2
49.375 mol methanol * 2 mol CO2/ 2 mol methanol = 49.375 mol CO2
Mass of CO2 = moles * molar mass
= 49.375 mol *44.01 g per mol
= 2173 g CO2
Therefore
a.What is the limiting reactant?
Methanol (CH3OH) is the limiting reactant
b.What reactant and how many grams of it are left over?
O2 reactant is left over and its mass is 77630 g
c.How many grams of carbon dioxide is produced?
Mass of CO2 produced = 2173 g