Question

How many atoms are in a 1.8 mol sample of Magnesium (Mg)?

Answer 1

Answer:

1.1 × 10²⁴ atoms Mg

General Formulas and Concepts:

Atomic Structure

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

Stoichiometry

• Using Dimensional Analysis

Explanation:

Step 1: Define

Identify

[Given] 1.8 mol Mg

[Solve] atoms Mg

Step 2: Identify Conversions

Avogadro's Number

Step 3: Convert

1. [DA] Set up:                                                                                                       $\displaystyle 1.8 \ mol \ Mg(\frac{6.022 \cdot 10^{23} \ atoms \ Mg}{1 \ mol \ Mg})$
2. [DA] Multiply [Cancel out units]:                                                                      $\displaystyle 1.08396 \cdot 10^{24} \ atoms \ Mg$

Step 4: Check

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

1.08396 × 10²⁴ atoms Mg ≈ 1.1 × 10²⁴ atoms Mg

Answer 2

Answer:  1.0836 * 10^24 atoms

This value is approximate

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Explanation:

1 mole = 6.02*10^23 atoms approximately

This applies to any element.

Multiply both sides by 1.8 and we get...

1 mole = 6.02*10^23 atoms

1.8*1 mole = 1.8*6.02*10^23 atoms

1.8 mole = 10.836*10^23 atoms

1.8 mole = (1.0836*10)*10^23 atoms

1.8 mole = 1.0836 * 10^(1+23)

1.8 mole = 1.0836 * 10^24 atoms