3RD QUATRER S.Y. 2012 - 2013: Stoichiometry Reviewer (EASY)

 _{EASY STOICHIOMETRY PROBLEMS}

1)      How many moles of sodium atoms correspond to 1.56x10²¹ atoms of sodium?

2)      How many moles of Al atoms are needed to combine with 1.58 mol of O atoms to make aluminum oxide, Al₂O₃?

3)      How many moles of Al are in 2.16 mol of Al₂O₃?

4)      Aluminum sulfate, Al₂(SO₄)₃, is a compound used in sewage treatment plants. 

a.     Construct a pair of conversion factors that relate moles of aluminum to moles of sulfur for this compound

b.     Construct a pair of conversion factors that relate moles of sulfur to moles of Al₂(SO₄)₃

c.       How many moles of Al are in a sample of this compound if the sample also contains 0.900 mol S?

d.     How many moles of S are in 1.16 mol Al₂(SO₄)₃?

5)      How many moles of H₂ and N₂ can be formed by the decomposition of 0.145 mol of ammonia, NH₃?

ANSWERS:

1)      2.59x10^-3mol Na atoms  

2)      1.05mol Al                

3)      4.32mol Al

4)      a. 2mol Al/3mol S            b. 3mol S/1mol Al₂(SO₄)₃            c. 0.600mol Al     d. 3.48mol S

5)      0.0725mol N₂ and 0.218mol H₂