Answer:
1. B = 1.13M
2. A. 8.46%
3. D = 0.0199
Explanation:
1. Molarity of a a solution = number of moles of solute/ volume of solution in L
Number of moles of solute = mass of solute/molar mass of solute
Molar mass of NaC₂H₃O₂ = 82 g/mol, mass of NaC₂H₃O₂ = 245 g
Number of moles of NaC₂H₃O₂ = 245 g / 82 g/mol = 2.988 moles
Molarity of solution = 2.988 mols/ 2.65 L = 1.13 M
2. Percentage by mass of a substance = mass of substance /mass of solution × 100%
Mass of 2.65 L of water = density × volume
Density of water = 1 Kg/L = 1000 g/L; volume of waterb= 2.65 L
Mass of water = 1000 g/L × 2.65 L = 2650 g
Mass of solution = mass of water + mass of solute = 245 + 2650 =2895 g
Percentage by mass of NaC₂H₃O₂ = 245/2895 × 100% = 8.46%
3. Mole fraction of NaC₂H₃O₂ = moles of NaC₂H₃O₂/moles of solution
Moles of water = mass /molar mass
Mass of water = 2650 g; molar mass of water = 18 g/mol
Moles of water = 2650 g / 18 g/mol = 147.222 moles
Moles of solution = moles of solute + moles of water = 147.222 + 2.988 = 150.21
Moles of NaC₂H₃O₂ =2.988 moles
Moles fraction of NaC₂H₃O₂ =2.988/150.21 = 0.0199
