Question

How many moles are in 2.8x10^24 atoms of silicon?

Answer 1

4.6 mol Si

General Formulas and Concepts:

Atomic Structure

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

Stoichiometry

• Using Dimensional Analysis

Step-by-step explanation:

Step 1: Define

[Given] 2.8 × 10²⁴ atoms Si

[Solve] moles Si

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

1. [DA] Set up:
   `\displaystyle 2.8 \cdot 10^(24) \ atoms \ Si((1 \ mol \ Si)/(6.022 \cdot 10^(23) \ atoms \ Si))`
2. [DA] Divide [Cancel like units]:
   `\displaystyle 4.64962 \ mol \ Si`

Step 4: Check

Follow sig fig rules and round. We are given 2 sig figs.

4.64962 mol Si ≈ 4.6 mol Si