Question

How many grams of H2O are formed from 7.8 grams of O2?

Answer 1

Answer:

Mass = 7.2 g

Explanation:

Given data:

Mass of water produced = ?

Mass of oxygen = 7.8 g

Solution:

Chemical equation:

2H₂ + O₂ → 2H₂O

Number of moles of oxygen:

Number of moles = mass/ molar mass

Number of moles = 7.8 g/ 32 g/mol

Number of moles = 0.2 mol

Now we will compare the moles of water with oxygen.

                       O₂           :          H₂O

                         1            :             2

                          0.2       :          2×0.2 = 0.4 mol

Mass of water:

Mass = number of moles × number of moles

Mass = 0.4 mol × 18 g/mol

Mass = 7.2 g