Grrrr i cant stand this, there must be an easy way?

Question

4(Al) + 3(O)2 = 2(Al)2(O)3
part 1. How many grams of aluminum oxide are produced when 50.5g aluminum react?
part 2. When 0.570 mole aluminum is reacted in a closed container with 8.00 g oxygen, how many grams of aluminum oxide can form?
i cant seem to get the right answer at all

Answer 1

I don't know what it is but some kids seem to get moles instantly and some other kids, including lots of good students, just can;t seem to get it.

When you are balancing an equation, the first thing you have to do is be POSITIVE that you have the formulas of the different compounds exactly correct. Otherwise you will never be able to balance things out.

You have to count up how many atoms of each element you have at the start (reactants) and how many at the end (product). If the numbers are not exactly the same, then you will have to adjust the coefficients (the number in front of the compounds) until you have exactly the same number of atoms of each element on each side.

Once you have the equation properly balanced, then it is really like a ratio - how many aluminum oxides are you going to get for each aluminum?

Say you balance the equation and have 4 aluminums for each 2 aluminum oxides. OK, then you check the molar mass of the compounds. Al has a molar mass of 27 so 4 moles of aluminum would be 108 grams of aluminum. That much aluminum will give you 2 moles of aluminum oxide. So what's the mass of Al2O3? 27 + 27 + 16+16+16 = 102 so two moles of Al2 O 3 would weigh 204 grams.

108 is to 204 as 50.5 is to X. This is just a ratio of how much aluminum gives how much aluminum oxide. Just follow that ratio and think about the other part of the question... and go see your chemistry teacher for extra help!

Good luck.