`you have to be careful about pouring drano down your pipes since it is mainly hydrochloric acid--you can't do it if they are made of aluminum because it will dissolve them! you can't acid clean your aluminum auto parts for the same reasons: 2 al + 6 hcl → 2 alcl3 + 3h2. if you wanted to make 10.0 moles of hydrogen gas, how many many moles of al would you need? note: all numbers located immediately after elemental symbols should be considered subscripts.

6.67 moles

Explanation:

Given that:-

Moles of hydrogen gas produced = 10.0 moles

According the reaction shown below:-

3 moles of hydrogen gas are produced when 2 moles of aluminium undergoes reaction.

Also,

1 mole of hydrogen gas are produced when moles of aluminium undergoes reaction.

So,

10.0 moles of hydrogen gas are produced when moles of aluminium undergoes reaction.

Moles of Al needed  = moles = 6.67 moles

the product of the pressure and volume is also constant