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Topic: need help...stoichiometry exercises  (Read 4300 times)

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Offline goodboy

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need help...stoichiometry exercises
« on: August 06, 2007, 02:46:41 AM »

problem is...

1. a 32.4 g sample of an alloy of Mg and Al produces 1.66mol of H2 gas when added with HCl, what percentage of the alloy is Mg??

The equations for the reactions are:

Mg + 2 HCl --> MgCl2 + H2
Al + HCl -->AlCl3 + H2...
I have no idea..thnx for a little help.

2. a 21.496 g sample of magnesium is burned in air to form magnesium oxide and magnesium nitride. when the products are treated with water, 2.813g of gaseous ammonia are generated. what are the amounts of magnesium nitride and magnesium oxide formed???

Offline Yggdrasil

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Re: need help...stoichiometry exercises
« Reply #1 on: August 06, 2007, 03:07:10 AM »

problem is...

1. a 32.4 g sample of an alloy of Mg and Al produces 1.66mol of H2 gas when added with HCl, what percentage of the alloy is Mg??

The equations for the reactions are:

Mg + 2 HCl --> MgCl2 + H2
Al + HCl -->AlCl3 + H2...
I have no idea..thnx for a little help.

First, one of your equations is not balanced.  Second, the first step I would take is to determine how much H2 is produced per gram of Mg and per gram of Al.

Quote
2. a 21.496 g sample of magnesium is burned in air to form magnesium oxide and magnesium nitride. when the products are treated with water, 2.813g of gaseous ammonia are generated. what are the amounts of magnesium nitride and magnesium oxide formed???

First, start with balanced chemical reactions describing the reactions that are happening.

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