2 C2H6 + 7 02 - > 4CO2 + 6H2O

If 15 g of C2H6 react with 45 g of O2, how many grams of water will be produced?

Mass of water = 21.6 g

Explanation:

Given dа ta:

Mass of C₂H₆ = 15 g

Mass of O₂ = 45 g

Mass of water produced = ?

Solution:

Chemical equation:

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Number of moles of C₂H₆:

Number of moles = mass / molar mass

Number of moles = 15 g / 30 g/mol

Number of moles = 0.5 mol

Number of moles of O₂:

Number of moles = mass / molar mass

Number of moles = 45 g / 32 g/mol

Number of moles = 1.4 mol

Now we will compare the moles of C₂H₆ and O₂ with H₂O.

C₂H₆ : H₂O

2 : 6

0.5 : 6/2*0.5 = 1.5

O₂ : H₂O

7 : 6

1.4 : 6/7*1.4 = 1.2

The number of moles of water produced by oxygen are less so it will limiting reactant.

Mass of water produced:

Mass = number of moles * molar mass

Mass = 1.2 mol * 18 g/mol

Mass = 21.6 g