Question

Number of atoms in 2.56 moles of He

Answer 1

1.54 × 10²⁴ atoms He

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Chemistry

Atomic Structure

• Moles
• Avogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.

Stoichiometry

• Using Dimensional Analysis

Step-by-step explanation:

Step 1: Define

[Given] 2.56 moles He

[Solve] atoms He

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

1. [DA] Set up:
   `\displaystyle 2.56 \ mol \ He((6.022 \cdot 10^(23) \ atoms \ He)/(1 \ mol \ He))`
2. [DA] Multiply [Cancel out units]:
   `\displaystyle 1.54163 \cdot 10^(24) \ atoms \ He`

Step 4: Check

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

1.54163 × 10²⁴ atoms He ≈ 1.54 × 10²⁴ atoms He