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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Zoloft on February 09, 2009, 12:30:48 AM

Title: Seems simple, but somehow confusing? What?
Post by: Zoloft on February 09, 2009, 12:30:48 AM

Hi everyone, I have this problem that I'm somewhat confused about. The problem is:

"An alloy of aluminum and magensium was treated with sodium hydroxide solution, in which only aluminum reacts to give hydrogen gas:

2Al + 2NaOH + 6H20 --> 2NaAl(OH)4 + 3H2

If a sample of alloy weighing 1.118 g gave 0.1068 g of hydrogen, what is the percentage aluminum in the alloy?"

How do I account for the magnesium and what stoichiometric relationships would I need to set-up? This is very confusing, but I appreciate the slightest of help on this!

Thank you.

Title: Re: Seems simple, but somehow confusing? What?
Post by: Borek on February 09, 2009, 03:00:23 AM

Magnesium is whatever solid will be left after the reaction, so if you know mass of the sample and mass of dissolved Al...