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's how to solve question 11: a) What is the molar mass of Sr_3(PO_4)_2? Step 1: Identify the atomic masses of each element. • Strontium (Sr): 87.62 g/mol • Phosphorus (P): 30.97 g/mol • Oxygen (O): 16.00 g/mol Step 2: Calculate the molar mass of Sr_3(PO_4)_2. The formula indicates 3 Sr atoms, 2 P atoms (from 2 × P in (PO_4)_2), and 8 O atoms (from 2 × 4 O in (PO_4)_2). Molar mass = (3 × 87.62) + (2 × 30.97) + (8 × 16.00) Molar mass = 262.86 + 61.94 + 128.00 Molar mass = 452.80 g/mol The molar mass of Sr_3(PO_4)_2 is 452.80 g/mol. b) How many moles are present in there? 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: Calculate the number of moles using the mass and the molar mass from part a. Moles = massmolar mass Moles = 0.0458 g452.80 g/mol Moles ≈ 0.000101148 mol Rounding to three significant figures: The number of moles present is 1.01 × 10^-4 mol. c) Determination 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. There are 2 phosphorus atoms in the formula Sr_3(PO_4)_2. 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 ≈ 0.136793 × 100\% Percentage composition of P ≈ 13.68\% The percentage composition of phosphorus is 13.68\%. That's 2 down. 3 left today — send the next one.