Question

4.18 L of oxygen, O2, at STP is how many molecules of O2?

Answer 1

Answer:

1.12 × 10²³ molecules O₂

General Formulas and Concepts:

Chemistry - Atomic Structure

• Using Dimensional Analysis
• Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
• STP (Standard Conditions for Temperature and Pressure) = 22.4 L per mole at 1 atm, 273 K

Explanation:

Step 1: Define

4.18 L O₂

Step 2: Identify Conversions

Avogadro's Number

STP - 22.4 L / mol

Step 3: Convert

$4.18 \ L \ O_2(\frac{1 \ mol \ O_2}{22.4 \ L \ O_2})(\frac{6.022 \cdot 10^{23} \ molecules \ O_2}{1 \ mol \ O_2} )$ = 1.12375 × 10²³ molecules O₂

Step 4: Check

We are given 3 sig figs. Follow sig fig rules and round.

1.12375 × 10²³ molecules O₂ ≈ 1.12 × 10²³ molecules O₂