Question

The number of molecules in 17.9 g of CO is

Answer 1

Answer:

3.85 × 10²³ molecules CO

General Formulas and Concepts:

Atomic Structure

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

Stoichiometry

• Using Dimensional Analysis

Explanation:

Step 1: Define

Identify

[Given] 17.9 g CO

[Solve] molecules CO

Step 2: Identify Conversions

Avogadro's Number

[PT] Molar Mass of C: 12.01 g/mol

[PT] Molar Mass of O: 16.00 g/mol

Molar Mass of CO: 12.01 + 16.00 = 28.01 g/mol

Step 3: Convert

1. [DA] Set up:                                                                                                       $\displaystyle 17.9 \ g \ CO(\frac{1 \ mol \ CO}{28.01 \ g \ CO})(\frac{6.022 \cdot 10^{23} \ molecules \ CO}{1 \ mol \ CO})$
2. [DA] Divide/Multiply [Cancel out units]:                                                           $\displaystyle 3.8484 \cdot 10^{23} \ molecules \ CO$

Step 4: Check

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

3.8484 × 10²³ molecules CO ≈ 3.85 × 10²³ molecules CO