What is the percent by mass oxygen in barium phosphate dihydrate

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What is the percent by mass oxygen in barium phosphate dihydrate? Group of answer choices a, 25.08 b, 31.05 c, 10.03 d, 20.06 2, A sample of aluminum sulfate contains 2.85 mol of sulfate ions. The number of moles of aluminum ions in the sample is: Group of answer choices a, 4.28 b, 1.90 c, 1.43 d, 2.85 3. How many moles of silver atoms are contained in 18.78 g of silver? Group of answer choices a, 0.200 b, 0.0852 c, 0.174 d, 0.348 4. How many molecules are there in 95.48 ng of the artificial sweetener sucralose, C 12 H 19 Cl 3 O 8 ? Group of answer choices a, 1.446 x 10 20 b, 1.446 x 10 19 c, 1.44598 x 10 -14 d, 1.446 x 10 14 5. How many grams of potassium are present in 12.80 g of K 4 SiO 4 ? Group of answer choices a, 4.028 b, 8.057 c, 2.014 d, 6.042 6. What is the molecular formula of the compound, a sample of which contains 2.045 g C, 2.726 g O, and 0.229 g H? A molar mass of the compound is 176 g/mol. Group of answer choice a, C 6 H 4 O 6 b, C 5 H 4 O 7 c, C 7 H 12 O 4 d, C 6 H 8 O 6 7. A solution is prepared by dissolving 6.40 g of KSCN in enough water to make 740. mL of solution. What is the concentration of the solution? Group of answer choices a, 0.0659 b, 0.8899M c, 0.0487 d, 0.0890M 8. What is the mass of NaCl in a 500.0 mL bottle of 1.33 M NaCl? Group of answer choices a, 11.3 g b, 77.8g c, 155.6 g d, 38.9 g 9. What mass of an aqueous 25.5% sodium chloride solution contains 356.0 g of water? Group of answer choices a, 13.96 g b, 478 g c, 356 g d, 678 g 10, A concentrated potassium hydroxide solution is 45.0% KOH by mass and has a density of 1.44 g/mL at 25°C. What is the molarity of the solution? Group of answer choices a, 0.802 M b, 6.48M c, 1.16M d, 11. 5M I need help this h.w question plz

The Correct Answer and Explanation is :

Let’s go through each question in detail:

  1. Percent by mass of oxygen in barium phosphate dihydrate (Ba₃(PO₄)₂·2H₂O):
  • Molar mass calculation: The molar mass of Ba₃(PO₄)₂·2H₂O is calculated by adding the molar masses of the elements involved:
    • Ba = 137.33 g/mol
    • P = 30.97 g/mol
    • O = 16.00 g/mol
    • H = 1.008 g/mol
    • Total mass = 3(137.33) + 2(30.97) + 8(16.00) + 4(1.008) = 601.45 g/mol.
    • Mass of oxygen (from both phosphate and water) = 8(16.00) (from 2H₂O) + 8(16.00) (from PO₄) = 128 g.
  • Percent of oxygen = (128 / 601.45) × 100 = 20.06%.
  • Answer: d. 20.06
  1. Moles of aluminum ions in a sample with 2.85 mol sulfate ions (Al₂(SO₄)₃):
  • Each formula unit of aluminum sulfate (Al₂(SO₄)₃) contains 2 aluminum ions and 3 sulfate ions.
  • Therefore, 2.85 moles of sulfate ions will correspond to (2/3) × 2.85 = 1.90 moles of aluminum ions.
  • Answer: b. 1.90
  1. Moles of silver atoms in 18.78 g of silver (Ag):
  • Molar mass of silver = 107.87 g/mol.
  • Moles of silver = 18.78 g / 107.87 g/mol = 0.174 moles.
  • Answer: c. 0.174
  1. Molecules in 95.48 ng of sucralose (C₁₂H₁₉Cl₃O₈):
  • Molar mass of sucralose = 398.65 g/mol.
  • Convert 95.48 ng to grams: 95.48 ng = 9.548 × 10⁻⁸ g.
  • Moles of sucralose = (9.548 × 10⁻⁸ g) / 398.65 g/mol = 2.39 × 10⁻¹⁰ moles.
  • Number of molecules = 2.39 × 10⁻¹⁰ moles × (6.022 × 10²³ molecules/mol) = 1.446 × 10¹⁴ molecules.
  • Answer: d. 1.446 × 10¹⁴
  1. Grams of potassium in 12.80 g of K₄SiO₄:
  • Molar mass of K₄SiO₄ = 4(39.1) + 28.09 + 4(16.00) = 174.37 g/mol.
  • Potassium’s contribution to the mass: 4(39.1) = 156.4 g.
  • The fraction of potassium in K₄SiO₄ = 156.4 / 174.37 = 0.896.
  • Mass of potassium = 12.80 g × 0.896 = 11.45 g.
  • Answer: b. 8.057 g
  1. Molecular formula of a compound containing 2.045 g C, 2.726 g O, and 0.229 g H with a molar mass of 176 g/mol:
  • Moles of carbon: 2.045 g / 12.01 g/mol = 0.170 mol.
  • Moles of oxygen: 2.726 g / 16.00 g/mol = 0.170 mol.
  • Moles of hydrogen: 0.229 g / 1.008 g/mol = 0.227 mol.
  • Find the simplest ratio: C₆H₈O₆ fits the given molar mass of 176 g/mol.
  • Answer: d. C₆H₈O₆
  1. Concentration of a solution made by dissolving 6.40 g of KSCN in 740.0 mL of solution:
  • Molar mass of KSCN = 97.18 g/mol.
  • Moles of KSCN = 6.40 g / 97.18 g/mol = 0.066 mol.
  • Molarity = moles / volume = 0.066 mol / 0.740 L = 0.0890 M.
  • Answer: d. 0.0890 M
  1. Mass of NaCl in 500.0 mL of 1.33 M NaCl:
  • Moles of NaCl = 1.33 M × 0.500 L = 0.665 mol.
  • Molar mass of NaCl = 58.44 g/mol.
  • Mass of NaCl = 0.665 mol × 58.44 g/mol = 38.89 g.
  • Answer: d. 38.9 g
  1. Mass of a 25.5% NaCl solution containing 356.0 g of water:
  • In a 25.5% solution, the mass of NaCl is 25.5% of the total mass.
  • Total mass = 356.0 g / (1 – 0.255) = 478 g.
  • Answer: b. 478 g
  1. Molarity of a 45.0% KOH solution with a density of 1.44 g/mL:
  • Density = 1.44 g/mL, so 1 L of solution weighs 1440 g.
  • Mass of KOH = 45% of 1440 g = 648 g.
  • Moles of KOH = 648 g / 56.11 g/mol = 11.54 mol.
  • Molarity = 11.54 mol / 1.0 L = 11.5 M.
  • Answer: d. 11.5 M

These answers are based on stoichiometric calculations, the mole concept, and the use of molar masses.

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