Question

The density of ethanol, C 2H 5OH, is 0.789 g/mL. How many milliliters of ethanol are needed to produce 25.0 g of CO 2 according to the following chemical equation?
C 2H 5OH( l) + 3 O 2( g) → 2 CO 2( g) + 3 H 2O( l)

Answer 1

Answer:

11.1mL

Explanation:

The reaction expression is given as:

          C₂H₅OH   + 3O₂ → 2CO₂ +  3H₂O

Given parameters:

density of ethanol  = 0.789g/mL

mass of CO₂ = 25g

Unknown:

Volume of ethanol = ?

Solution:

First find the number of moles of the CO₂ from the given mass;

 Number of moles  = $\frac{mass}{molar mass}$

 Molar mass of CO₂ = 12 + 2(16) = 44g/mol

Number of moles  = $\frac{25}{44}$    = 0.57mol

Then;

 Find the number of moles of ethanol used;

     3 moles of CO₂ is produced from 1 mole of ethanol;

    0.57mole of CO₂ will be produced from $\frac{0.57}{3}$  = 0.19mole of ethanol

Now;

Find the mass of the ethanol from the given mole;

     Mass of ethanol  = number of moles x molar mass

     Molar mass of ethanol  = 2(12) + 5(1) + 16 + 1 = 46g/mol

      Mass of ethanol  = 0.19 x 46 = 8.74g

Then;

  Density is the mass per unit volume of a substance;

       Density  = $\frac{mass}{volume}$

        Volume  = $\frac{mass}{density}$  

          Volume  = $\frac{8.74}{0.789}$   = 11.1mL