Hello, Josh,
Please add anything you can about which part you understand and which part is confusing. The question covers balancing equations, predicting molecular formulas, and calculating with moles. I don't have the time, nor space, to help on all three steps in detail. So I'll give you some starters and would ask you try them out. IIdentify which step is confusing and post a followup question that we can respond to with a better explanation.
The first thing we need is a balanced equation. To do that we need the molecular formula of aluminum sulfate. The sulfate ion has a chage of -2. Aluminum is usually +3. That would mean that aluminum sulfate would likely have the formula Al2(SO4)3.
Without going throgh the details, the balanced equation for this reaction would be:
2Al + 3H2SO4 = Al2(SO4)3 + 3H2
Count the individual elements and see if they equal each other on both sides. Al: Reactants: 2, Products:2, S: Reactants: 3, Products: 3, and so on.
Once balanced, let's convert the 13.2 grams of hydrogen into moles H2.
The molar mass of H2 is 1x2 or 2 grams/mole. 13.2 grams i converted into moles by dividing it by the molar mass:
13.2 grams/(2 grams/mole) = 6.6 moles H2
We can see from the balanced equation that 3 it takes 2 moles of Al to make 3 moles of H2. That is a molar ratio of 2/3, or 0.666 . . We produced 6.6 moles of H2, so to find the moles of Al requires, multiply by 0.666, to get 4.4 moles of Al. Convert that into grams aluminum by multiplying by the molar mass of Al.
It takes 118.8 grams of Al to make 13.2 grams of H2
I hope this helps,
Bob
