Which is the weakest acid. HCL , H3P04, H2PO4^- , HPO4 ^2-​

Ithink its called the coefficent.

Moles = mass/molar mass by this formula 458/207+32 you should get your answer the ans. is 1.916 mol to 4 sig. fig.

Answer is: mass of hydrochloric acid is 4,08 grams.chemical reaction: 2hcl + mg(oh)₂ → mgcl₂ + 2h₂o.m(mg(oh)₂) = 3,26 g.n(mg(oh)₂) = m(mg(oh)₂)  ÷ m(mg(oh)₂).n(mg(oh)₂) = 3,26 g  ÷ 58,32 g/mol.n(mg(oh)₂) = 0,056 mol.from chemical reaction: n(mg(oh)₂) : n(hcl) = 1 : 2.n(hcl) = 2  · 0,056 mol = 0,112 mol.m(hcl) = 0,112 mol  · 36,45 g/mol.m(hcl) = 4,08 g.