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Question:

How do I calculate how many moles of H2 there are?

Equation: Al + 3HCL Al^3+ + 3/2H2Moles of Aluminum: 0.000678The equation is balancedI think I am supposed to cross multiply the ratios of HCL and Al, but I don't know how to do that with 3/2 in there and I'm just very confusedMy lab is in a few hours, any help is good enough! Thank you.

Answer:

First you need a balanced equation: 2 Al(s) + 6 HCl(aq) - 2 AlCl3 + 3 H2(g) Well you take the moles of aluminum and multiple it by the ratio 0.000678 mols Al (x moles of what your looking for it / x moles of Al) 0.000678 mols Al (3 mol H2 /2 mol Al) - mol of Al cancels, leaves mols of H2 0.001017 mol H2 sigdigs 1.02 10^-3 mol H2

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