How many grams of hydrochloric acid will react completely with a block of gold that is 3.2 cm by 3.8 cm by 2.8 cm, if the density of gold is 19.3 g/ml?

The chemical reaction would be:

2Au + 2HCl = 2AuCl + H2

First, we need to determine the mass of gold that is used in the reaction. We do this by multiplying the volume of the block of gold to its density. We do as follows:

Mass of Au = (3.2 cm) (3.8 cm) (2.8 cm) ( 1 mL / 1 cm^3) ( 19.3 g/ mL) = 657.1264 g Au

From the molar mass of Au which is 197 g/mol, we convert the mass of Au to moles and relate HCl by using the balanced reaction. We do as follows:

657.1264 g Au ( 1 mol / 197 g ) ( 2 mol HCl / 2 mol Au ) ( 36.46 g / mol ) = 121.62 g HCl

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.