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

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Answer:

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

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:                    [tex]\displaystyle 255 \ g \ Mg(OH)_2(\frac{1 \ mol \ Mg(OH)_2}{58.33 \ g \ Mg(OH)_2})(\frac{1 \ mol \ MgCl_2}{1 \ mol \ Mg(OH)_2})(\frac{95.21 \ g \ MgCl_2}{1 \ mol \ MgCl_2})[/tex]
  2. Multiply/Divide:                                                                                               [tex]\displaystyle 416.227 \ g \ MgCl_2[/tex]

Step 4: Check

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

416.227 g MgCl₂ ≈ 416 g MgCl₂