Question

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

Answer 1

Answer:

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

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:                                                                                                   $\displaystyle 2.8 \cdot 10^{24} \ atoms \ Si(\frac{1 \ mol \ Si}{6.022 \cdot 10^{23} \ atoms \ Si})$
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