Question

12 grams of magnesium will react completely with acid to give​

Answer 1

Answer:

to find the mole of H2 produced for 12gm of Mg with an acid

you can pick 2 acids...a dibasic and monobasic acid

Mg + 2HCl ......MgCl2 + H2 ( 1 mole of hydrogen)

Mg + H2So4 .......MgSo4 + H2 ( 1 mole of hydrogen)

in both instances the mole of H produced is 1 and the mole ratio of Mg:H2 is 1:1 .

this means that if there is 1 mole of Mg then there will be 1 mole of H2..

moles of 12g Mg

moles = mass/ molar mass

molar mass of magnesium = 24

moles = 12/24 = 0.5 mole

the ratio was 1:1 then the moles of hydrogen produced will also be 0.5 moles...

therefore...if 12g Mg reacts with an acid half of a mole of hydrogen gas is produced...

Answer 2

Answer:

Mg + 2HCl = MgCl2 + H2

So One mole of Mg reacts with 2 moles of H2 and gives 1 mole of H2

Now, as atomic weight of Mg=24, no. of moles of Mg present = 0.5

as 1 mole of Mg reacts with 2 moles of HCl to give 1 mole H2

0.5 moles of Mg will react with 1 mole of HCl to give 0.5 moles of H2