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 your chemistry questions: 7.1. A compound is a substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio. 7.2. To calculate the percentage of chromium in K₂Cr₂O₇: Step 1: Determine the molar mass of K₂Cr₂O₇. The atomic masses are approximately: K = 39.10 g/mol, Cr = 52.00 g/mol, O = 16.00 g/mol. Molar mass of K_2Cr_2O_7 = (2 × 39.10) + (2 × 52.00) + (7 × 16.00) = 78.20 + 104.00 + 112.00 = 294.20 g/mol Step 2: Calculate the total mass of chromium in one mole of K₂Cr₂O₇. Mass of Cr = 2 × 52.00 g/mol = 104.00 g/mol Step 3: Calculate the percentage of chromium. Percentage of Cr = Mass of CrMolar mass of K_2Cr_2O_7 × 100\% = 104.00 g/mol294.20 g/mol × 100\% = 35.35\% The percentage of chromium in K₂Cr₂O₇ is 35.35%. 7.3.1. An empirical formula shows the simplest whole-number ratio of atoms of each element in a compound. 7.3.2. To determine the empirical formula for the compound: Step 1: Assume a 100 g sample and convert percentages to masses. • Mass of Oxygen (O) = 65.31 g • Mass of Sulphur (S) = 32.65 g • Mass of Hydrogen (H) = 2.04 g Step 2: Convert the mass of each element to moles using their atomic masses (O = 16.00 g/mol, S = 32.07 g/mol, H = 1.01 g/mol). Moles of O = 65.31 g16.00 g/mol = 4.08 mol Moles of S = 32.65 g32.07 g/mol = 1.02 mol Moles of H = 2.04 g1.01 g/mol = 2.02 mol Step 3: Divide each mole value by the smallest number of moles to find the simplest ratio. The smallest number of moles is 1.02 mol (for Sulphur). Ratio for O = (4.08)/(1.02) ≈ 4 Ratio for S = (1.02)/(1.02) = 1 Ratio for H = (2.02)/(1.02) ≈ 2 Step 4: Write the empirical formula using these whole-number ratios. The empirical formula is H_2SO_4. Got more? Send 'em!