To determine the amount of magnesium chloride produced, we need to use the balanced chemical equation for the reaction between magnesium and hydrochloric acid:Mg s + 2 HCl aq MgCl aq + H g First, we need to determine the limiting reactant. To do this, we'll use the molar masses of the reactants and the stoichiometry of the balanced equation.Molar mass of Mg = 24.31 g/molMolar mass of HCl = 36.46 g/molMoles of Mg = 20 g / 24.31 g/mol = 0.822 molMoles of HCl = 30 g / 36.46 g/mol = 0.822 molNow, we'll use the stoichiometry of the balanced equation to determine the limiting reactant:Moles of Mg needed for complete reaction with HCl = 0.822 mol HCl / 2 = 0.411 mol MgSince we have 0.822 mol of Mg, there is enough Mg to react with all the HCl. Therefore, HCl is the limiting reactant.Now, we can determine the amount of magnesium chloride produced using the stoichiometry of the balanced equation:Moles of MgCl produced = 0.822 mol HCl * 1 mol MgCl / 2 mol HCl = 0.411 mol MgClFinally, we'll convert moles of MgCl to grams:Molar mass of MgCl = 95.21 g/molMass of MgCl = 0.411 mol MgCl * 95.21 g/mol = 39.11 gSo, 39.11 grams of magnesium chloride will be produced in a complete reaction between magnesium and hydrochloric acid.