This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
ScanSolve AI Answer
Hey ~Excel — ready when you are. Step 1: Calculate the molar mass of KMnO_4. The molar mass of potassium (K) is 39.098 g/mol. The molar mass of manganese (Mn) is 54.938 g/mol. The molar mass of oxygen (O) is 15.999 g/mol. Molar mass of KMnO_4 = 39.098 + 54.938 + (4 × 15.999) = 158.032 g/mol Step 2: Convert the concentration from ppm to Molarity (mol/L). A concentration of 25 ppm means 25 mg of KMnO_4 per liter of solution. First, convert milligrams to grams: 25 mg = 0.025 g Now, calculate the moles of KMnO_4 in 1 L of solution: Moles of KMnO_4 = MassMolar mass = 0.025 g158.032 g/mol ≈ 1.58195 × 10^-4 mol The molar concentration (C) is: C = 1.58195 × 10^-4 mol1 L = 1.58195 × 10^-4 M Step 3: Calculate the molar absorptivity (). The Beer-Lambert Law is given by A = C L, where A is absorbance, is molar absorptivity, C is molar concentration, and L is the path length. Given: A = 0.674 C = 1.58195 × 10^-4 mol/L L = 5 cm Rearrange the formula to solve for : = (A)/(C L) Substitute the values: = (0.674)/((1.58195 × 10^-4) mol/L) × (5 cm) = (0.674)/(7.90975 × 10^-4) mol cm/L ≈ 852.00 L mol^-1 cm^-1 Rounding to two significant figures (due to 25 ppm), the molar absorptivity is: ≈ 850 L mol^-1 cm^-1 Step 4: Determine the molar absorptivity in a 1 cm cell. Molar absorptivity () is an intrinsic property of the substance at a specific wavelength. It does not depend on the cell path length. Therefore, the molar absorptivity remains the same regardless of the cell length. The molar absorptivity of KMnO_4 at 515 nm is 850 L mol^-1 cm^-1. The molar absorptivity in a 1 cm cell will also be 850 L mol^-1 cm^-1. Send me the next one 📸