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: To solve these problems, we need the atomic masses of the elements: • 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: Calculate the total mass contributed by each element in the compound. The compound Sr_3(PO_4)_2 contains: • 3 atoms of Strontium (Sr) • 2 atoms of Phosphorus (P) (since there are two PO_4 groups) • 8 atoms of Oxygen (O) (since there are two PO_4 groups, and each has 4 oxygen atoms, 2 × 4 = 8) Step 2: Sum the masses to find the molar mass. Molar mass = (3 × atomic mass of Sr) + (2 × atomic mass of P) + (8 × atomic mass of O) Molar mass = (3 × 87.62 g/mol) + (2 × 30.97 g/mol) + (8 × 16.00 g/mol) 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 ≈ 0.0001011 mol Moles ≈ 1.011 × 10^-4 mol The number of moles present is 1.011 × 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, we know 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. 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 ≈ 0.13679 × 100\% Percentage composition of P ≈ 13.68\% The percentage composition of phosphorus in Sr_3(PO_4)_2 is 13.68\%.