Question

The chemical equation represents the formation of water.

2 H2 + O2 → 2 H2O

What is the total number of grams of O2 needed to produce 54 grams of water?
A
36

B
48

C
61

D
75

Answer 1

Answer:

The total number of grams of O2 is 48.0 grams (option B)

Explanation:

Step 1: Data given

Mass of water = 54.0 grams

Molar mass of water (H2O) = 18.02 g/mol

Step 2: The balanced equation

2 H2 + O2 → 2 H2O

Step 3: Calculate moles of H2O

Moles H2O = mass H2O / molar mass H2O

Moles H2O = 54.0 grams / 18.02 g/mol

Moles H2O = 3.00 moles

Step 4: Calculate moles O2

For 2 moles H2 we need 1 mol O2 to produce 2 moles H2O

For 3.00 moles H2O we need 3.00/2 = 1.50 moles O2

Step 5: Calculate mass O2

Mass O2 = moles O2 * molar mass O2

Mass O2 = 1.50 moles * 32.0 g/mol

Mass O2 = 48.0 grams

The total number of grams of O2 is 48.0 grams (option B)