Question

A student preforms a chemical reaction in which 35 grams of hydrogen and 65 grams of oxygen reacted to form water. What is the mass of the products?

Answer 1

Mass of water = 73.08 g

Step-by-step explanation:

Given data:

Mass of hydrogen = 35 g

Mass of oxygen = 65 g

Mass of water = ?

Solution:

First of all we will write the balanced chemical equation:

2H₂ + O₂ → 2H₂O

Number of moles of hydrogen = mass/ molar mass

Number of moles of hydrogen = 35 g/ 2 g/mol

Number of moles of hydrogen = 17.5 mol

Number of moles of oxygen = 65 g / 32 g/mol

Number of moles of oxygen = 2.03 moles

Now we compare the moles of water with moles hydrogen and oxygen.

H₂ : H₂O

2 : 2

17.5 : 17.5

O₂ : H₂O

1 : 2

2.03 : 2× 2.03 =4.06 mol

Number of moles of water produced by oxygen are less so oxygen is limitting reactant.

Mass of water:

Mass of water = number of moles × molar mass

Mass of water = 4.06 mol × 18 g/mol

Mass of water = 73.08 g