How many grams of silver oxide are needed to react with 7.9 g of hydrochloric acid produce silver chloide and water?

25.11 g.

Explanation:

It is clear from the balanced equation:

Ag₂O + 2HCl → 2AgCl + H₂O.

that 1.0 mole of Ag₂O reacts with 2.0 moles of HCl to produce 2.0 mole of AgCl and 1.0 moles of H₂O.

7.8 g of HCl reacts with excess Ag₂O. To calculate the no. of grams of Ag₂O that reacted, we should calculate the no. of moles of HCl:

no. of moles of HCl = mass/atomic mass = (7.9 g) / (36.46 g/mol) = 0.2167 mol.

From the balanced equation; every 1.0 mol of Ag₂O reacts with 2 moles of HCl.

∴ 0.2167 mol of HCl will react with (0.2617 mol / 2 = 0.1083 mol) of Ag₂O.

∴ The mass of reacted Ag₂O = no. of moles x molar mass = (0.1083 mol) (231.735 g/mol) = 25.11 g.