Question

What is the mass, in grams, of MgCl2 is consumed when 255g Mg(OH)2 is produced?

MgCl2 + 2 LiOH → Mg(OH)2 + 2 LiCl

Answer 1

416 g MgCl₂

General Formulas and Concepts:

Math

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Chemistry

Atomic Structure

• Reading a Periodic Table

Stoichiometry

• Using Dimensional Analysis

Step-by-step explanation:

Step 1: Define

[RxN - Balanced] MgCl₂ + 2LiOH → Mg(OH)₂ + 2LiCl

[Given] 255 g Mg(OH)₂

[Solve] x g MgCl₂

Step 2: Identify Conversions

[RxN] 1 mol MgCl₂ → 1 mol Mg(OH)₂

[PT] Molar Mass of Mg - 24.31 g/mol

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

[PT] Molar Mass of H - 1.01 g/mol

[PT] Molar Mass of Cl - 35.45 g/mol

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

Molar Mass of MgCl₂ - 24.31 + 2(35.45) = 95.21 g/mol

Step 3: Stoichiometry

1. Set up conversion:
   `\displaystyle 255 \ g \ Mg(OH)_2((1 \ mol \ Mg(OH)_2)/(58.33 \ g \ Mg(OH)_2))((1 \ mol \ MgCl_2)/(1 \ mol \ Mg(OH)_2))((95.21 \ g \ MgCl_2)/(1 \ mol \ MgCl_2))`
2. Multiply/Divide:
   `\displaystyle 416.227 \ g \ MgCl_2`

Step 4: Check

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

416.227 g MgCl₂ ≈ 416 g MgCl₂