In chemistry laboratories, you will often use a brilliant, dark-purple crystalline powder that turns water violently pink. This chemical is Potassium Permanganate (KMnO₄), a highly powerful oxidizing agent used in titrations.
To prepare a precise chemical solution for a titration experiment, you must first calculate its exact Molar Mass. The calculated molar mass of KMnO₄ is 158 g/mol.
Chemical Name: Potassium Permanganate.
Total Molar Mass: 158 g/mol (or 158.03 g/mol for extreme decimal accuracy).
Formula Breakdown: KMnO₄ = 1 Potassium, 1 Manganese, 4 Oxygens.
Atomic Mass Values Used: K=39, Mn=55, O=16.
Appearance: Dark purple, nearly black crystalline solid.
To calculate the molar mass, you must look at the periodic table, extract the atomic mass of every single individual atom in the formula, and add them all up.
The formula KMnO₄ contains exactly 1 Potassium atom, 1 Manganese atom, and 4 Oxygen atoms.
Step 1: Write down the individual atomic masses:
Step 2: Multiply by the number of atoms and add them up:
Step 3: Total Sum Total Mass = 39 + 55 + 64 = 158 g/mol.
If a Class 12 chemistry teacher asks you to prepare exactly '1 Molar (1 M)' solution of pink Potassium Permanganate in a 1-liter flask, you do not just guess the amount. You simply weigh exactly 158.0 grams of the dark purple crystals on a digital scale, dump it into the flask, and fill the rest with pure water.
The molar mass of KMnO₄ (Potassium Permanganate) is exactly 158 g/mol.
You add the atomic masses of 1 Potassium (39), 1 Manganese (55), and 4 Oxygens (4x16). The sum is 39 + 55 + 64 = 158.
The standard atomic mass of a single Manganese (Mn) atom is 55 atomic mass units (u).
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