Q.34 The mass of 1 kmol of oxygen molecules is _______ g (rounded off to the nearest integer).
Answer
The mass of 1 kmol of oxygen molecules is 32000 g. This value comes from the molar mass of O₂ (32 g/mol) scaled by the kilogram-mole definition.
Detailed Solution
Oxygen exists as diatomic molecules (O₂). Each oxygen atom has an atomic mass of 16 u, so the molecular mass of O₂ is 2 × 16 = 32 u.
One kilomole (kmol) equals 1000 moles, making the mass of 1 kmol equal to 1000 times the molar mass in grams: 32 g/mol × 1000 = 32000 g.
Rounded to the nearest integer, this remains exactly 32000, as no decimal component exists.
Options Analysis
No explicit multiple-choice options appear in the query, but common alternatives from similar problems include:
- 32 g: Mass of 1 mol (not kmol) of O₂.
- 16000 g: Mass of 1 kmol of atomic oxygen (O), not O₂ molecules.
- 16 g: Mass of 1 mol of atomic oxygen.
These fail because the question specifies O₂ molecules and kmol units.
The mass of 1 kmol of oxygen molecules is a fundamental calculation in chemistry and engineering, equaling 32000 g when rounded to the nearest integer. This key phrase reflects the precise molar mass scaling for diatomic O₂ in kilomole units.
Molar Mass Basics
Oxygen molecules (O₂) have a molecular mass of 32 g/mol since each atom contributes 16 g/mol. A kmol represents 1000 mol, so multiply: 32 × 1000 = 32000 g.
This applies in biotechnology for gas stoichiometry and reactor design.
Step-by-Step Calculation
- Atomic mass of O: 16 u.
- O₂ molecular mass: 32 u (or g/mol).
- 1 kmol mass: 32,000 g.
No rounding needed beyond integer precision.
Common Exam Pitfalls
Confusing mol (32 g) with kmol (32000 g) or atomic O (16000 g/kmol) trips students. Use O₂ formula explicitly for molecules.
