📘 Step-by-Step Solution
Step 1: Given Data
Mass of H₂O = 18 g
We need to calculate the number of moles of H₂O.
Step 2: Calculate the Molar Mass of H₂O
Atomic masses:
H = 1 g mol⁻¹
O = 16 g mol⁻¹
O = 16 g mol⁻¹
Since H₂O contains 2 hydrogen atoms and 1 oxygen atom:
Molar Mass of H₂O
= (2 × 1) + (1 × 16)
= 2 + 16
= 18 g mol⁻¹
= (2 × 1) + (1 × 16)
= 2 + 16
= 18 g mol⁻¹
🎬 H₂O Molecular Animation
H
H
O
H₂O = 18 g mol⁻¹
One mole of H₂O has a mass of 18 grams.
Step 3: Use the Mole Formula
Number of moles (n)
=
Mass ÷ Molar Mass
Step 4: Substitute the Values
n = 18 ÷ 18
n = 1 mol
n = 1 mol
🎬 Mass → Moles Animation
18 g H₂O
÷
18 g mol⁻¹
→
1 mol H₂O
Mass divided by molar mass gives the number of moles.
✅ Final Answer
Number of moles of H₂O = 1 mol
Therefore, 18 g of H₂O contains 1 mole of H₂O.
🎯 Quick Formula
n = m / M
n = 18 / 18
n = 1 mol
n = 18 / 18
n = 1 mol
