calculate how many moles of CaCl2•2H2O are present in 1.50 g of CaCl2•2H2O and then calculate how many moles of pure CaCl2 are present in the 1.50 g of CaCl2•2H2O.

0.0102moles CaCl₂.2H₂O

0.0102moles CaCl₂

Explanation:

To convert moles to grams or vice versa of a compound, it is necessary to find molar mass of this substance.

For the CaCl₂.2H₂O:

This is the calcium chloride dihydrate (Because there are 2 molecules of water). That means you have 1 atom of Ca, 2 atoms of Cl, 4 atoms of H and 2 atoms of C. Molar mass is the algebraic sum of the atomic weights that compose the molecule.

Molar mass:

Ca: 1ₓ40.08g/mol = 40.08g/mol

Cl: 2ₓ35.45g/mol = 70.90g/mol

H: 4ₓ1.01g/mol: 4.04g/mol

O: 2ₓ16g/mol: 32g/mol.

40.08 + 70.90 + 4.04 + 32 = 147.02g/mol

By using the molar mass of the susbtance, 1.50g are:

1.50g ₓ (1mol / 147.02g) =

0.0102moles CaCl₂.2H₂O

In the 1.50g of CaCl₂.2H₂O you have 0.0102 moles. As you can see, 1 mole of the dihydrate substance contains 1 mole of CaCl₂. Thus, you have:

0.0102moles CaCl₂

Ais the correct answer

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.