Question

What will be the amount of oxygen in gm units in 4.6 moles of water?

• A. 16 g
• B. 38.8 g
• C. 73.6 g
• D. 82.6 g

Hint:

Always look at the subscript. If the question asked for Hydrogen, you would multiply by 2 (moles) and then by 1 (atomic mass), because there are 2 Hydrogen atoms for every 1 Water molecule.

Answer 1

The Correct Option is C

Concept: A mole represents a specific quantity of a substance. In a chemical formula like $H_2O$, the subscripts indicate the molar ratio of the elements. One mole of water ($H_2O$) contains exactly one mole of oxygen atoms ($O$).

Step 1: Determining the Moles of Oxygen.
1 mole of $H_2O \rightarrow 1$ mole of $O$
Therefore, 4.6 moles of $H_2O$ contain 4.6 moles of Oxygen.

Step 2: Converting Moles to Grams.
The molar mass of Oxygen ($O$) is approximately $16 \text{ g/mol}$. \[ \text{Mass} = \text{Moles} \times \text{Molar Mass} \] \[ \text{Mass} = 4.6 \text{ moles} \times 16 \text{ g/mol} = 73.6 \text{ g} \]