Phosphorus reacts with water to form hydrochloric acid and phosphoric acid. how many moles of acid are formed when starting with 4.5 g of PCl5 and excess H2o?

Something is missing here. How can you get HCl out of P4 and H2O?

To determine the number of moles of acid formed when 4.5 g of PCl5 reacts with excess water, we need first to balance the chemical equation:

PCl5 + H2O → HCl + H3PO4

According to the balanced equation, one mole of PCl5 reacts to produce one mole of HCl and one mole of H3PO4. To find the molar mass of PCl5, we need to know the molar mass of each element in the compound:

P = 31 g/mol
Cl = 35.5 g/mol (x 5 = 177.5 g/mol)
Total molar mass of PCl5 = 208.5 g/mol

Next, we'll calculate the number of moles of PCl5:

moles of PCl5 = mass of PCl5 / molar mass of PCl5
moles of PCl5 = 4.5 g / 208.5 g/mol ≈ 0.0216 mol

Since the reaction is given as excess water, all of the PCl5 will react. This means that we will obtain an equal number of moles of HCl and H3PO4.

Therefore, the number of moles of acid formed (HCl + H3PO4) will be approximately 0.0216 mol.