Answer:
79.7 g He
General Formulas and Concepts:
Chemistry - Atomic Structure
- Reading a Periodic Table
- Using Dimensional Analysis
- Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.
Explanation:
Step 1: Define
1.20 × 10²⁵ atoms He
Step 2: Identify Conversions
Avogadro's Number
Molar Mass of He - 4.00 g/mol
Step 3: Convert
[tex]1.20 \cdot 10^{25} \ atoms \ He(\frac{1 \ mol \ He}{6.022 \cdot 10^{23} \ atoms \ He} )(\frac{4.00 \ g \ He}{1 \ mol \ He} )[/tex] = 79.7077 g He
Step 4: Check
We are given 3 sig figs. Follow sig fig rules and round.
79.7077 g He ≈ 79.7 g He
