What is the mass of aluminum metal that releases 22.4 l of hydrogen gas at stp from hydrochloric acid? __al (s) + __hcl (aq) → __alcl3 (aq) + __h2 (g) 18.0 g 81.0 g 9.00 g 40.5 g 27.0 g?

The mass of Al metal that releases 2.4 L of hydrogen gas at STP is calculated as below

AT STP 1 mole = 22.4 l

what about 22.4l = ? moles

(22.4 L x 1 mole) / 22.4 L = 2mole

write the reacing reaction

2Al + 6 HCL = 2AlCl3 + 3H2

by use of mole ratio between Al to H2 which is 2 : 3 the mole Al = 1 x2/3 = 0.667 moles

mass = moles x molar mass

=0.667 mole x27 g/mol = 18 grams