Calculate the mass in g of each of the following.
a. 2.3×10^22 H2O molecules
b. 6.16×10^20 SO3 molecules
c. 5.0×1025 O3 molecules
d. 9.82×1019 CCl2F2 molecules
2.3 x 10^22/6.022 x 10^23 = ?? moles H2O.
g = mols x molar mass.
Same process for the others.
To calculate the mass of each substance, you need to know the molar mass of the molecule. The molar mass represents the mass of one mole of that substance and is usually expressed in grams per mole (g/mol).
a. H2O molecules:
The molar mass of H2O is calculated by adding the atomic masses of two hydrogen atoms (H) and one oxygen atom (O):
H = 1.007 g/mol
O = 15.999 g/mol
Molar mass of H2O = (2 × H) + O = (2 × 1.007) + 15.999 = 18.015 g/mol
To determine the mass of 2.3 × 10^22 H2O molecules, you will calculate the mass of one mole of H2O molecules and then convert it to grams.
Number of moles = Number of molecules / Avogadro's number
Number of moles = (2.3 × 10^22) / (6.022 × 10^23 mol^-1) = 0.038 mol
Mass = Number of moles × Molar mass
Mass = 0.038 mol × 18.015 g/mol ≈ 0.685 g
Therefore, the mass of 2.3 × 10^22 H2O molecules is approximately 0.685 grams.
You can follow a similar process to calculate the mass for the remaining substances.
b. SO3 molecules:
First, determine the molar mass of SO3.
S = 32.06 g/mol
O = 15.999 g/mol
Molar mass of SO3 = S + (3 × O) = 32.06 + (3 × 15.999) = 80.06 g/mol
Number of moles = Number of molecules / Avogadro's number
Number of moles = (6.16 × 10^20) / (6.022 × 10^23 mol^-1) = 0.001 mol
Mass = Number of moles × Molar mass
Mass = 0.001 mol × 80.06 g/mol = 0.08006 g
Therefore, the mass of 6.16 × 10^20 SO3 molecules is approximately 0.08006 grams.
c. O3 molecules:
The molar mass of O3 is calculated by adding the atomic masses of three oxygen atoms (O):
O = 15.999 g/mol
Molar mass of O3 = 3 × O = 3 × 15.999 = 47.997 g/mol
Number of moles = Number of molecules / Avogadro's number
Number of moles = (5.0 × 10^25) / (6.022 × 10^23 mol^-1) = 82.96 mol
Mass = Number of moles × Molar mass
Mass = 82.96 mol × 47.997 g/mol = 3,980.99 g
Therefore, the mass of 5.0 × 10^25 O3 molecules is approximately 3,980.99 grams.
d. CCl2F2 molecules:
First, determine the molar mass of CCl2F2.
C = 12.01 g/mol
Cl = 35.453 g/mol (2 Cl atoms)
F = 18.998 g/mol (2 F atoms)
Molar mass of CCl2F2 = C + (2 × Cl) + (2 × F) = 12.01 + (2 × 35.453) + (2 × 18.998) = 120.913 g/mol
Number of moles = Number of molecules / Avogadro's number
Number of moles = (9.82 × 10^19) / (6.022 × 10^23 mol^-1) = 0.016 mol
Mass = Number of moles × Molar mass
Mass = 0.016 mol × 120.913 g/mol = 1.934 g
Therefore, the mass of 9.82 × 10^19 CCl2F2 molecules is approximately 1.934 grams.