How many moles of hydrogen gas can be evolved from the action of excess hydrochloric acid on a mass of #4.8*g# of magnesium metal?

1 Answer
anor277
Apr 6, 2017

Approx. #4.8*L#

Explanation:

We assess the following chemical reaction:

#Mg(s) + 2H_3O^(+) rarr Mg^(2+) + H_2(g) +2H_2O(l)#

And thus #"moles of metal"# #-=# #"moles of dihydrogen gas."#

#"Moles of metal"# #=# #"Mass"/"Molar mass"#

#=(4.8*g)/(24.3*g*mol^-1)=0.198*mol#.

And this #0.198*mol# #"dihydrogen gas is evolved"#.

The molar volume of an ideal gas under standard conditions is #24*dm^3#. (The definitions now vary across the different syllabuses, so I cannot be much help to you here). And so the volume of gas evolved is:

#0.198*molxx24*dm^3*mol^-1=??dm^3#.

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