This mathematics problem involves applying core mathematical principles and formulas. Below you will find a complete step-by-step solution with detailed explanations for each step, helping you understand not just the answer but the method behind it.
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You're on a roll — Here are the solutions to questions 4-7: 4. A solution of NaOH contains 4.0g of NaOH in 250ml of solution. Calculate the molarity of the solution. (Na=23, O=16, H=1) Step 1: Calculate the molar mass of NaOH. Molar mass of NaOH = (1 × 23) + (1 × 16) + (1 × 1) = 23 + 16 + 1 = 40 g/mol Step 2: Calculate the number of moles of NaOH. Moles of NaOH = MassMolar mass = 4.0 g40 g/mol = 0.10 mol Step 3: Convert the volume of the solution from milliliters to liters. Volume of solution = 250 mL = 0.250 L Step 4: Calculate the molarity of the solution. Molarity = Moles of soluteVolume of solution (L) = 0.10 mol0.250 L = 0.4 M 5. Calculate the mass of Na_2CO_3 required to prepare 250ml of 0.1M solution. (Na=23, C=12, O=16) Step 1: Calculate the molar mass of Na_2CO_3. Molar mass of Na_2CO_3 = (2 × 23) + (1 × 12) + (3 × 16) = 46 + 12 + 48 = 106 g/mol Step 2: Convert the volume of the solution from milliliters to liters. Volume of solution = 250 mL = 0.250 L Step 3: Calculate the number of moles of Na_2CO_3 required. Moles of Na_2CO_3 = Molarity × Volume (L) = 0.1 M × 0.250 L = 0.025 mol Step 4: Calculate the mass of Na_2CO_3 required. Mass of Na_2CO_3 = Moles × Molar mass = 0.025 mol × 106 g/mol = 2.65 g 6. Calculate the volume of 0.2M HCl required to neutralize 25ml of 0.1M NaOH. (HCl + NaOH NaCl + H_2O) Step 1: Write the balanced chemical equation and determine the mole ratio. The given equation is HCl + NaOH NaCl + H_2O. From the equation, 1 mole of HCl reacts with 1 mole of NaOH. The mole ratio is 1:1. Step 2: Convert the volume of NaOH solution from milliliters to liters. Volume of NaOH = 25 mL = 0.025 L Step 3: Calculate the number of moles of NaOH. Moles of NaOH = Molarity × Volume (L) = 0.1 M × 0.025 L = 0.0025 mol Step 4: Use the mole ratio to find the moles of HCl required. Since the mole ratio of HCl to NaOH is 1:1, Moles of HCl = Moles of NaOH = 0.0025 mol Step 5: Calculate the volume of HCl solution required. Volume of HCl (L) = Moles of HClMolarity of HCl = 0.0025 mol0.2 M = 0.0125 L Convert to milliliters: Volume of HCl = 0.0125 L × 1000 mL/L = 12.5 mL 7. Calculate the percentage by mass of water of crystallization in Na_2CO_3 · 10H_2O. (Na=23, C=12, O=16, H=1) Step 1: Calculate the molar mass of Na_2CO_3 · 10H_2O. Molar mass of Na_2CO_3 = (2 × 23) + (1 × 12) + (3 × 16) = 46 + 12 + 48 = 106 g/mol Molar mass of H_2O = (2 × 1) + (1 × 16) = 2 + 16 = 18 g/mol Molar mass of 10H_2O = 10 × 18 = 180 g/mol Total molar mass of Na_2CO_3 · 10H_2O = 106 + 180 = 286 g/mol Step 2: Calculate the percentage by mass of water of crystallization. Percentage by mass of H_2O = Mass of 10H_2OTotal molar mass of Na_2CO_3 · 10H_2O × 100\% = 180 g/mol286 g/mol × 100\% ≈ 62.94\% Send me the next one 📸