Question

Molecules in 2.5 mol aluminum sulfate.

a) Al₂(SO₄)₃
b) Al₂S₃
c) Al₂O₃
d) Al₂CO₃

Answer 1

The formula mass of aluminum sulfate, Al2(SO4)3, is calculated by multiplying the number of each type of atom by their respective atomic mass and summing them up, resulting in a formula mass of 342.14 amu.

Step-by-step explanation:

To calculate the formula mass of aluminum sulfate, Al2(SO4)3, we consider the atomic masses of aluminum (Al), sulfur (S), and oxygen (O). The formula Al2(SO4)3 can be written in a simpler form as Al2S3O12, which indicates there are 2 aluminum atoms, 3 sulfur atoms, and 12 oxygen atoms in one formula unit of the compound.

Using the periodic table, we find the atomic masses for the elements: Al (approximately 26.98 amu), S (approximately 32.06 amu), and O (approximately 16.00 amu). So, the formula mass is calculated as follows:

Adding these sums together yields a total formula mass:
53.96 amu (Al) + 96.18 amu (S) + 192.00 amu (O) = 342.14 amu for aluminum sulfate.

Answer 2

To find the number of molecules in 2.5 moles of aluminum sulfate (Al₂(SO₄)₃), multiply 2.5 moles by Avogadro's number to get 1.506 × 1024 molecules of Al₂(SO₄)₃.

Step-by-step explanation:

The student is asking about the number of molecules in 2.5 mol of aluminum sulfate, which is represented by the formula Al₂(SO₄)₃. To find the number of molecules, we use Avogadro's number, which is approximately 6.022 × 1023 molecules per mole. Thus, the calculation is as follows:
2.5 mol Al₂(SO₄)₃ × (6.022 × 1023 molecules/mol) = 1.506 × 1024 molecules of Al₂(SO₄)₃

Therefore, there are 1.506 × 1024 molecules of aluminum sulfate in 2.5 moles of the compound.