An unknown mass of aluminum is added to HCl solution. The aluminum metal is completely dissolved in the solution and generates hydrogen gas. See the balanced equation for the gas evolution reaction: 2 Al(s) + 6 HCl(aq) ---> 2 AlCl3(aq) + 3 H2(g) The following data is collected: Mass of Al sample:                             unknown  g Volume of gas collected                     45.38 mL Barometric pressure                            754.8 mmHg Temperature

An unknown mass of aluminum is added to HCl solution. The aluminum metal is completely dissolved in the solution and generates hydrogen gas. See the balanced equation for the gas evolution reaction:

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

The following data is collected:

Mass of Al sample:                             unknown  g

Volume of gas collected                     45.38 mL

Barometric pressure                            754.8 mmHg

Temperature                                        23.5^OC

Vapor pressure of H₂O at 23.5^OC       21.65 mmHg

Hydrogen gas is collected over water. The reaction proceeds until all the amount of aluminum is consumed in the gas-evolution reaction (aluminum is the limiting reactant).

(a) Calculate the mole number of the hydrogen gas generated in the reaction:

• Convert the volume of the collected gas to L:  45.38 mL = ___________ L
• Calculate the pressure exerted by H₂ gas (= dry hydrogen gas):

         Pressure of the dry hydrogen gas

         = barometric pressure −vapor pressure of H₂O(g)

         = 754.8 mmHg − 21.65 mmHg

         = _________ mmHg

• Determine the pressure of dry hydrogen gas in atm: 

          __________ mmHg = ___________ atm

• Convert the temperature to kelvin unit: 23.5^OC = ________ K
  
  Use the ideal gas law to calculate the mole number of hydrogen gas collected: n=PVRT

         mole number of hydrogen gas collected = _____________ mol

(b) Use stoichiometry to determine the mass of Al that reacted in this experiment.

     mass of Al = ____________ g