6) Hydrogen gas can be generated from the reaction between aluminum metal and hydrochloric acid: 2 Al(s) + 6 HCl(aq) + 2 AICI3, (aq) + 3 H2(g)
a. Suppose that 3.00 grams of Al are mixed with excess acid. If the hydrogen gas produced is directly collected
into a 850 mL glass flask at 24.0 °C, what is the pressure inside the flask (in atm)?
b. This hydrogen gas is then completely transferred from the flask to a balloon. To what volume (in L) will the
balloon inflate under STP conditions?
c. Suppose the balloon is released and rises up to an altitude where the temperature is 11.2 °C and the pressure is
438 mm Hg. What is the new volume of the balloon (in L)?

Stoichiometry refers to the relationship between the moles of reactants and products.

This question must be solved using both stoichiometry and the gas laws

The reaction equation is;

2 Al(s) + 6 HCl(aq) > 2 AICI3, (aq) + 3 H2(g)

Number of moles of Al = 3g/27g/mol = 0.11 moles

According to the reaction equation;

2 moles of Al yields 3 moles of H2

0.11 moles of Al yields 0.11 * 3/2 = 0.165 moles

From the ideal gas equation;

PV=nRT

P = ?

n= 0.165 moles

V = 0.85 L

T = 297 K

R = 0.082 atmLK-1mol-1

P= nRT/V

P = 0.165 * 0.082 * 297/0.85

P= 4.73 atm

P1 = 4.73 atm

T1 = 297 K

V1 = 0.85 L

P2 = 1 atm

T2 =273 K

V2 =?

P1V1/T1 = P2V2/T2

P1V1T2 = P2V2T1

V2 = P1V1T2/P2T1

V2 =  4.73 * 0.85 * 273/1 * 297

V2 = 3.69 L

P1 = 760 mmHg

T1 = 273 K

V1 = 3.69

P2 = 438 mm Hg

T2 = 284.2 K

V2 =?

P1V1/T1 = P2V2/T2

P1V1T2 = P2V2T1

V2 = P1V1T2/P2T1

V2 = 760 * 3.69 * 284.2/438 *273

V2 = 797010.48/119574

V2= 6.67 L