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.
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Here are the solutions to the problems from the image. To solve these problems, we will use the following atomic masses: Strontium (Sr): 87.62 g/mol Phosphorus (P): 30.97 g/mol Oxygen (O): 16.00 g/mol I. What is the molar mass (g/mol) of Sr_3(PO_4)_2? Step 1: Determine the number of atoms of each element in the compound Sr_3(PO_4)_2. Strontium (Sr): 3 atoms Phosphorus (P): 2 × 1 = 2 atoms (from the (PO_4)_2 group) Oxygen (O): 2 × 4 = 8 atoms (from the (PO_4)_2 group) Step 2: Calculate the total mass contributed by each element. Mass from Sr: 3 × 87.62 g/mol = 262.86 g/mol Mass from P: 2 × 30.97 g/mol = 61.94 g/mol Mass from O: 8 × 16.00 g/mol = 128.00 g/mol Step 3: Sum the masses to find the molar mass of Sr_3(PO_4)_2. Molar mass = 262.86 g/mol + 61.94 g/mol + 128.00 g/mol Molar mass = 452.80 g/mol The molar mass of Sr_3(PO_4)_2 is 452.80 g/mol. II. How many moles are present in 45.8 mg? Step 1: Convert the given mass from milligrams (mg) to grams (g). 45.8 mg = 45.8 × 10^-3 g = 0.0458 g Step 2: Use the molar mass calculated in Part I to find the number of moles. Moles = massmolar mass Moles = 0.0458 g452.80 g/mol Moles ≈ 0.000101148 mol Moles ≈ 1.01 × 10^-4 mol The number of moles present is 1.01 × 10^-4 mol. III. Determination of the percentage composition of phosphorus atom in this compound. Step 1: Calculate the total mass of phosphorus in one mole of Sr_3(PO_4)_2. From Part I, there are 2 phosphorus atoms in the compound. Total mass of P = 2 × atomic mass of P Total mass of P = 2 × 30.97 g/mol = 61.94 g/mol Step 2: Calculate the percentage composition of phosphorus using the molar mass from Part I. Percentage composition of P = total mass of Pmolar mass of Sr_3(PO_4)_2 × 100\% Percentage composition of P = 61.94 g/mol452.80 g/mol × 100\% Percentage composition of P ≈ 0.136793 × 100\% Percentage composition of P ≈ 13.68\% The percentage composition of phosphorus in Sr_3(PO_4)_2 is 13.68\%.