Question

How many moles of oxygen, O, are there in 479.07 g of iron (III) oxide, Fe₂O₃? Molar mass of Fe₂O₃ is 159.69 g/mol.

9.00 MOL

3.00 MOL

1.00 MOL

0.333 MOL

From the Balanced Chemical Equation: 4 Al + 3O₂ --> 2 Al₂O₃

Apply Stoichiometry to determine the yield (grams) of Al₂O₃ produced if you start with 108 grams of Al in excess O2 as reactants. Aluminum is the limiting reactant, and oxygen is present in excess. The formula weight of Al₂O₃ is 101.96 g/mol.

54g

210g

240g

101.96g

239g

Acid HCl reacts with base Mg(OH)2 (milk of magnesia antacid) in an acid-base neutralization in a human stomach. If a patient has secreted 5.0 ml of 2.0M acid and you (a medical professional) wish to administer a pill of pure Mg(OH)2, what pill size (in milligrams) do you need to administer?

600mg

290 mg

10 mg

0.60 mg

Answer 1

How many moles of oxygen, O, are there in 479.07 g of iron (III) oxide, Fe2O3? Molar mass of Fe2O3 is 159.69 g/mol.

apply the next formula

mol = mass/(molar mass)

mol of Fe2O3 = mass/MW = 479.07/159.69 = 3 mol of Fe2O3

note that

1 mol of Fe2O3 contains 3 mol of O3

then

3 mol o must contain triple amount,

that is

3*3 = 9 mol of Oxygen

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