Answer:
Step-by-step explanation:
To determine the mass in grams for each of the given substances, we need to use their respective molar masses. The molar mass is the mass of one mole of a substance and is expressed in grams per mole (g/mol).
a) Lead (Pb) has a molar mass of approximately 207.2 g/mol. Therefore, the mass of 2.9 mol of lead is calculated as follows:
Mass = Number of moles × Molar mass
Mass = 2.9 mol × 207.2 g/mol
Mass ≈ 600.88 g
b) Dichlorine heptafluoride (Cl2F7) has a molar mass of approximately 265.77 g/mol. Thus, the mass of 6.33 mol of dichlorine heptafluoride is:
Mass = 6.33 mol × 265.77 g/mol
Mass ≈ 1,681.86 g
c) Magnesium hydroxide (Mg(OH)2) has a molar mass of approximately 58.33 g/mol. Hence, the mass of 8.25 mol of magnesium hydroxide is:
Mass = 8.25 mol × 58.33 g/mol
Mass ≈ 480.08 g
Moving on to the second part of the question:
a) To find the mass of 5.18 × 10^25 atoms of calcium (Ca), we need to know the atomic mass of calcium, which is approximately 40.08 g/mol. The mass can be calculated using the following steps:
Number of moles = Number of atoms / Avogadro's number
Number of moles = (5.18 × 10^25 atoms) / (6.022 × 10^23 mol^-1)
Number of moles ≈ 8.61 mol
Mass = Number of moles × Molar mass
Mass = 8.61 mol × 40.08 g/mol
Mass ≈ 344.83 g
b) Tetraphosphorus decaoxide (P4O10) has a molar mass of approximately 283.88 g/mol. The mass of 6.76 × 10^22 molecules of tetraphosphorus decaoxide can be calculated as follows:
Number of moles = Number of molecules / Avogadro's number
Number of moles = (6.76 × 10^22 molecules) / (6.022 × 10^23 mol^-1)
Number of moles ≈ 0.112 mol
Mass = Number of moles × Molar mass
Mass = 0.112 mol × 283.88 g/mol
Mass ≈ 31.82 g
c) Aluminum oxide (Al2O3) has a molar mass of approximately 101.96 g/mol. The mass of 4.91 × 10^23 formula units of aluminum oxide can be calculated as follows:
Number of moles = Number of formula units / Avogadro's number
Number of moles = (4.91 × 10^23 formula units) / (6.022 × 10^23 mol^-1)
Number of moles ≈ 0.815 mol
Mass = Number of moles × Molar mass
Mass = 0.815 mol × 101.96 g/mol
Mass ≈ 83.24 g