Calculation of Potassium Chloride in a Potassium Supplement

Problem Statement

• Given:
  • A 0.450 gram potassium supplement.
  • The supplement contains 22% potassium by mass.
  • The potassium is present as Potassium Chloride (KCl) with a molar mass of 74.55 g/mol.
• Find: Grams of potassium chloride in the supplement.

Key Concepts

• Atomic Mass of Potassium (K): 39.10 g/mol
• Molar Mass of Potassium Chloride (KCl): 74.55 g/mol
• Percentage by Mass Formula: Total mass × Percentage / 100

Steps to Solve

Step 1: Calculate Mass of Potassium

• Formula: Mass of Potassium = Total mass of supplement × Percentage mass of Potassium
• Calculation: 0.450 g × 0.22 = 0.099 g

Step 2: Convert Mass of Potassium to Moles

• Formula: Moles of Potassium = Mass of Potassium / Atomic Mass of Potassium
• Calculation: 0.099 g / 39.10 g/mol = 0.00253 moles of Potassium

Step 3: Relate Moles of Potassium to Moles of Potassium Chloride

• Concept: 1 mole of K = 1 mole of KCl
• Moles of K = Moles of KCl = 0.00253 moles

Step 4: Find Mass of Potassium Chloride

• Formula: Mass of KCl = Moles of KCl × Molar Mass of KCl
• Calculation: 0.00253 moles × 74.55 g/mol = 0.189 g

Result

• Grams of KCl in Supplement: 0.189 g

Additional Considerations

• Significant Figures: The final answer is rounded to three significant figures based on the given data.