2 NH3 (g) + CO2 (g) CO(NH2)2 (l) + H2O (g) a. What is the limiting reagent? NH3 is the LR (produces 0.635 mol urea) b. What mass of urea can be produced from this reaction? Dr. When aluminum reacts with concentrated hydrochloric acid, hydrogen gas evolves. The hydrogen is collected by displacement of water at 22C at a total pressure of 750 torr. If the volume of the collected gas is 365 mL, how many moles of hydrogen were collected?