Question

How many molecules are in 650.0 g Mg(OH)₂ ?

Answer 1

6.711 × 10²⁴ molecules Mg(OH)₂

General Formulas and Concepts:

Chemistry - Atomic Structure

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

Step-by-step explanation:

Step 1: Define

650.0 g Mg(OH)₂

Step 2: Define conversions

Avogadro's Number

Molar Mass of Mg - 24.31 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of H - 1.01 g/mol

Molar Mass of Mg(OH)₂ - 24.31 + 2(16.00) + 2(1.01) = 58.33 g/mol

Step 3: Convert

`650.0 \ g \ Mg(OH)_2((1 \ mol \ Mg(OH)_2)/(58.33 \ g \ Mg(OH)_2) )((6.022 \cdot 10^(23) \ molecules \ Mg(OH)_2)/(1 \ mol \ Mg(OH)_2) )`

= 6.71061 × 10²⁴ molecules Mg(OH)₂

Step 4: Check

We are given 4 sig figs. Follow sig fig rules.

6.71061 × 10²⁴ molecules Mg(OH)₂ ≈ 6.711 × 10²⁴ molecules Mg(OH)₂