Question

Challenge Write the chemical formula for potassium permanganate, and then calculate the mass in grams of 2.55 mol of the compound.

Short answer

The chemical formula for potassium permanganate is KMnO4. The molar mass of KMnO4 is calculated as follows: Molar mass of KMnO4 = (1 × 39.10) + (1 × 54.94) + (4 × 16.00) = 158.04 g/mol. To find the mass of 2.55 mol of the compound, use the formula: Mass = moles × molar mass, resulting in: Mass = 2.55 mol × 158.04 g/mol = 402.802 g. Therefore, the mass of 2.55 mol of potassium permanganate is approximately 402.80 grams.

Step-by-step solution

Determine the chemical formula for potassium permanganate

Potassium is represented by the symbol "K" and has a charge of +1 (K+). Permanganate has the general formula MnO4^- and has a charge of -1. To balance the charges, we need one K+ ion for every MnO4^- ion, so the chemical formula for potassium permanganate is KMnO4.

Calculate the molar mass of potassium permanganate

To find the molar mass of KMnO4, we need to add the molar masses of the individual atoms in the compound. According to the periodic table: - Molar mass of K = 39.10 g/mol - Molar mass of Mn = 54.94 g/mol - Molar mass of O = 16.00 g/mol The molar mass of KMnO4 is calculated as follows: Molar mass of KMnO4 = (1 × 39.10) + (1 × 54.94) + (4 × 16.00) Molar mass of KMnO4 = 39.10 + 54.94 + 64.00 Molar mass of KMnO4 = 158.04 g/mol

Calculate the mass of 2.55 mol of potassium permanganate

Now that we have both the moles and molar mass of potassium permanganate, we can calculate the mass using the formula: Mass = moles × molar mass Mass = 2.55 mol × 158.04 g/mol Mass = 402.802 g So, the mass of 2.55 mol of potassium permanganate is approximately 402.80 grams.

Key concepts

Potassium Permanganate

Potassium permanganate is a well-known chemical compound used in a variety of applications, from water purification to disinfectants.
The chemical formula for this compound is denoted as \( \text{KMnO}_4 \). This chemical formula represents that one potassium (K), one manganese (Mn), and four oxygen (O) atoms come together to form a neutral compound.
The compound is noted for its deep purple color and oxidizing properties.
Understanding the correct chemical formula is crucial, and it involves recognizing the charges of ions. Potassium has a charge of +1, shown as K^+, and permanganate, represented as MnO_4^-, has a charge of -1.
Balancing these charges gives us the stable ionic compound KMnO₄, where each positive charge is balanced by an equal negative charge.

Molar Mass

To calculate the mass of a compound, it is essential to first determine its molar mass.
Molar mass is the weight in grams of one mole of a substance.
For potassium permanganate (KMnO₄), the calculation involves adding up the molar masses of each atom included in the formula. - Potassium (K) has a molar mass of 39.10 g/mol.- Manganese (Mn) has a molar mass of 54.94 g/mol.- Each oxygen (O) atom has a molar mass of 16.00 g/mol, and there are four oxygen atoms.The total molar mass of potassium permanganate is computed as follows:\[(1 \times 39.10) + (1 \times 54.94) + (4 \times 16.00) = 158.04 \text{ g/mol}\]This means that every mole of KMnO₄ weighs 158.04 grams. Calculating molar masses is an invaluable skill in chemistry as it translates laboratory measurements into quantities needed for stoichiometry.

Stoichiometry

Stoichiometry in chemistry involves the measurement of amounts in chemical reactions.
It allows you to predict the quantities of reactants and products involved.
For instance, by knowing the molar mass of potassium permanganate, we can easily determine how many grams are present in a given number of moles.
In the exercise, 2.55 moles of KMnO₄ are converted to grams:\[\text{Mass} = \text{moles} \times \text{molar mass} \\text{Mass} = 2.55 \, \text{mol} \times 158.04 \, \text{g/mol} \approx 402.80 \, \text{g}\]This calculation is crucial for reacting the correct proportion of substances in chemical reactions.
Mastery of stoichiometry ensures precision in experiments and formulation.

Chemical Compounds

Chemical compounds consist of atoms from different elements bonded together in definite proportions.
Potassium permanganate is a great example where different types of atoms come together to form a compound.
Compounds have unique properties that differ from the elements making them up.
Each compound's chemical formula reveals the types and numbers of atoms involved.
Understanding the formation of compounds like KMnO₄ requires familiarity with chemical bonds and formulas.

• Ionic compounds such as KMnO₄ form between metals and nonmetals, where electrons are transferred from one atom to another.
• The formula also indicates how elements interact within the compound, governed by the balance of positive and negative ions.

Chemical compounds are the basic building blocks of chemical reactions and are essential in both industrial applications and biological systems.