A level chemistry help

I get reacting masses questions however im having some trouble with this, im aware its regarded as an easy question but here goes:

A student reacted 5.2g of aluminium with hydrochloric acid. Calculate the mass of gas evolved from the reaction.
ive wrote down the balanced equation however the thing i dont understand is what the aluminum has to do with the production of hydrogen? Also can someone just explain the full question. Thanks

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Reply 1

jmushtaq

Metal + acid = salt + hydrogen

I’m guessing the reaction takes place in a solution of deionised water so the reactants form ions. 3 hydrochloric acid molecules dissociate into 3 protons and 3 chloride ions. The 3 chloride ions react with the 3+ charge on the aluminium ion, balancing the charges, forming aluminium chloride. 2 out of the 3 protons react to form hydrogen in its gaseous form. Dunno what happens to the 3rd proton. Maybe it’s reused, maybe it form a hydronium ion or maybe it just stays as it is. I dunno, man. I don’t even know if this is correct. What is life?

Reply 2

sjp955

Original post by Anonymous__02

okay so I assume that hydrogen is being evolved. Then the balanced equation is:
2Al + 6HCl --> 2AlCl3 +3H2

Thus, using n=mass/Mr, figure out the moles of Al (5.2/27=0.193). Since Al2 ratio is 2:3, the moles of gas is (0.193/2)*3=0.289moles.
Then using mass=n*Mr, you can calculate the mass of gas.

Reply 3

username4966870

Original post by sjp955

i kinda got this but still whats the relation between al as a solid and h2 produced?

Reply 4

sjp955

Original post by Anonymous__02

i kinda got this but still whats the relation between al as a solid and h2 produced?

I don't really understand what you are asking. If the above equation is the correct and correctly balanced equation, the al will react in HCl (it will probably dissolve), to form an ionic solution whilst also producing hydrogen gas. The equation is the realtionship betwen Al and H2.

With a correct balanced equation you can use moles to calculate the mass of the product formed, because 2 moles of Al will react to form 3H2 when reacted with HCl.

Reply 5

Ðeggs

Original post by Anonymous__02

i kinda got this but still whats the relation between al as a solid and h2 produced?

This is the reaction. A metal and an acid yields an ionic compound (a salt) and the excess hydrogen is given off as gas, as H2 is a gas at room temperature.

Reply 6

jmushtaq

Original post by Anonymous__02

i kinda got this but still whats the relation between al as a solid and h2 produced?

Mate, did u skip over my explanation. I think it was pretty solid

Reply 7

Ðeggs

Original post by Deggs_14

This is the reaction. A metal and an acid yields an ionic compound (a salt) and the excess hydrogen is given off as gas, as H2 is a gas at room temperature.

Original post by Anonymous__02

i kinda got this but still whats the relation between al as a solid and h2 produced?

It would be the same for mot other common metals you’d find in a chemistry question.
2Na + 2HCl —-> 2NaCl + H2
Mg + 2HCl —-> MgCl2 + H2

Reply 8

username4966870

oh ok i get it now. i just want to see if i got this one right now.
Calculate the mass of aluminium chloride made in the following equation from 54.0 g of aluminum.
2Al+3Cl2---------> 2AlCl3

Reply 9

username4966870

Original post by jmushtaq

that last bit had me dying lmaooo

Reply 10

Ðeggs

Original post by Anonymous__02

that last bit had me dying lmaooo

I think you would just write 1.5 H2.

Reply 11

username4966870

Original post by Deggs_14

I think you would just write 1.5 H2.

youre probably trolling but why would i write that

Reply 12

username4966870

Original post by Anonymous__02

oh ok i get it now. i just want to see if i got this one right now.
Calculate the mass of aluminium chloride made in the following equation from 54.0 g of aluminum.
2Al+3Cl2---------> 2AlCl3

anyone?

Reply 13

Marcuston

Original post by Anonymous__02

anyone?

Pretty obvious dude, the guy already explained it. Work out the mole of Aluminium by doing Mass ÷ Mr then do a mole-to-mole ratio with Aluminium chloride to get the Mole of it, then do Mole × Mr to get Mass of Aluminum Chloride.

Reply 14

jmushtaq

Original post by Anonymous__02

youre probably trolling but why would i write that

No no, you can do that. I dunno why but u can

Reply 15

Marcuston

Original post by jmushtaq

What? Lol

Reply 16

sjp955

Original post by Anonymous__02

oh ok i get it now. i just want to see if i got this one right now.
Calculate the mass of aluminium chloride made in the following equation from 54.0 g of aluminum.
2Al+3Cl2---------> 2AlCl3

if the question gives that as the equation, then yes balance it and use mole equations to find the mass