Question (1 Viewer)

[Twickel]

Hi
This must be basic for all of you but how to do this question?

Construct balanced ionic equations for the reaction of aluminium with the following acids:
a dilute sulfuric acid

The answer is this, I dont understand how they got that, forget the balancing, I just want to know the products. Why is H2O produced, if H2 and a salt are formed from reactions with dilute acids. Im probably missing something big here.

Thanks

 

[Twickel]

Here is the answer

2Al(s) + 12H+(aq) + 6SO42–(aq) → 2Al3+(aq) + 6(SO4)2–(aq) + 3SO2(g) + 6H2O(g)

 

[foram]

Hi
This must be basic for all of you but how to do this question?

Construct balanced ionic equations for the reaction of aluminium with the following acids:
a dilute sulfuric acid

The answer is this, I dont understand how they got that, forget the balancing, I just want to know the products. Why is H2O produced, if H2 and a salt are formed from reactions with dilute acids. Im probably missing something big here.

Thanks

sulfuric acid is special. as well as nitric acid i think.

 

[brenton1987]

Here is the answer
2Al(s) + 12H+(aq) + 6SO42–(aq) → 2Al3+(aq) + 6(SO4)2–(aq) + 3SO2(g) + 6H2O(g)

2Al + 3H₂SO₄ --> Al₂(SO_₄)₃ + 3H₂

The products 2H₂O + SO₂ only occur for the reaction with tin.

 

[Twickel]

In what way?
CURSE HAVING THE WORSE CHEMISTRY TEACHER EVER. PLEASE BE DIFFERENT NEXT YEAR.

Hey do you mind doing that unbalanced? Thanks for your help.

So the book made a mistake?

 

[Twickel]

So, are you sure thats right? thats what I got. But the books answer?

 

[xiao1985]

Suphate, so it seems, can be reduced in a lot ways. That makes the question very difficult to answer.

Firstly, clearly, alumininium is oxidised:

ox: Al (s) ---> Al 3+ + 3e-

In the reduction half equations, a number of things can happen:

re1: 2H+ + 2e- --- > H2 (g) ... 0.0V
re2: SO4 2- + 4H+ + 2e- ----> 2 H2O (l) + SO2 (g) ... 0.2V (Sielberberg, 4th ed)
re3: HSO4 - + H+ + 2e- ----> S2O62- ... -0.25V *
re4: HSO4 - + 3H+ + 2e- -----> H2SO3 + H2O ... 0.16V *
( *http://www.webelements.com/webelements/elements/text/S/redn.html)
re5: 4H+ + O2 ---> 2H2O (l) ... 1.23V
(http://www.jesuitnola.org/upload/clark/refs/red_pot.htm)

In the presence of oxygen, re4 will happen. Otherwise, it is likelly that re2 will happen (yielding the textbook answer)

 

[Undermyskin]

As far as I know, sulfuric acid and nitric acid give gases depending of the reactivities of the metals. The more reactive the metal is, the less likely the reaction is going to give any gas.

 

[Twickel]

So what would the ionic formula look like?