Question

Aluminum reacts with excess hydrochloric acid to form aqueous aluminum chloride and 30.7 mL of hydrogen gas over water at 27°C and 751 mmHg. How many grams of aluminum reacted? The partial pressure of water at 27°C is 26.8 mmHg. g Al

Answer 1

total pressure (PT) = 751mmHg

partial pressure of water at 27⁰C(PH2O) = 26.8mmHg

PH2   = PT-PH2O

         = 751-26.8

          = 724.2mmHg

        = 724.2/760

          = 0.953atm

V = 30.7ml   = 0.0307L

T   = 27+273   = 300K

PV   = nRT

n   = PV/RT

      = 0.953*0.0307/(0.0821*300)

     = 0.001187moles

2Al(s) + 6HCl(aq) -----------> 2AlCl3(aq) + 3H2(g)

3 moles of H2 produced from 2 moles of Al

0.001187moles of H2 produced from = 2*0.001187/3   = 0.0008 moles of Al

mass of Al   = no of moles * gram atomic mass

                   = 0.0008*27

                    = 0.0216g of Al >>>>answer