# Can aluminum and hydrochloric acid be used to generate hydrogen gas?

I am looking to produce hydrogen gas in a small amount with supplies I currently have. Most of the methods I have seen involve reacting zinc or magnesium with $\ce{HCl}$ to obtain the gas, but I do not have zinc or magnesium at the moment.

Is there any reason why aluminum cannot be used just as effectively as zinc? According to the reactivity series, aluminum should be even more reactive than zinc.

• Obviously, as has been shown, Aluminum works well. Is there a reason why it can't be used as effectively as Zinc? Yes. 1) It tends to take some time to start reacting because of its oxide coating and 2) In my experience it is more reactive so it sometimes is harder to keep cool and you end up with more steam and vapor. I prefer Zinc because it tends to start easier with HCl in an ice bath, and not accelerate as fast as it gets warmer. You can scour the Aluminum to get it started. Iron works too. – Joseph Hirsch Dec 28 '16 at 17:55

Yes. See this video for a demonstration.

The reaction is: $$\ce{ 2Al (s) + 6 HCl (aq) -> 2AlCl3 (s) + 3H2(g)}$$

You can capture the hydrogen and proceed with your experiments.

The fact that aluminium may reduce H(+I) to H(0) can be made clear by studying the standard reduction potentials. By definition, the reduction potential

$$E^0_{\ce{H^{+1}} \ \rightarrow \ce{H^{0}}} = 0 V$$

From a regular Latimer diagram, we see that the reduction potential

$$E^0_{\ce{Al^{+3}} \ \rightarrow \ce{Al^{0}}} = -1.676 V$$

Since you are studying the opposite reaction, oxidation of Al, we change sign of the potential. Thus the total $E^0$ for the reaction (at standard conditions) is positive, which indicates a spontaneous reaction (although the kinetics may be slow).

In addition, the precipitation of $\ce{AlCl3}$ drives the reaction toward $\ce{H2}$ production.

Magnesium or calcium would also work well, but they are more expensive. Aluminum is a safe bet.