Arkansas State University  Department of Chemistry and Physics
CHEM1003	Exam 3

Exam 3                                                                             Name_________________________
CHEM1003                                                                     Spring 1996
Show work on all problems for full credit

1. How many moles of O is in 4.5 moles of P₂O₅? (8 points)
 
 
 
 
 
 
 
 

2. How many O atoms are in 3 moles of CO₂? (8 points)
 
 
 
 
 
 
 
 

3. How many moles of C would you have if you have 8.4 x 10²⁴ atoms of C?       (8 points)
 
 
 
 
 
 
 
 

4. What is the mass of 5.64 mol of Mo?   (8 points)
 
 
 
 
 
 
 
 
 

5. Give the empirical formula for each of the following: Be sure to circle the correct answer.  (10 points)

 a)  P₄O₁₀                                                 b)  Mn₂(CO)₁₀
 
 
 

 c)  Hg₂O₂                                                 d)  C₄H₁₀
 
 
 

 e)  Fe₃(PO₄)₂
 
 
 

6. What is the percent composition of Ru₂(CO₃)₃?     (10 points)
 
 
 
 
 
 
 
 
 
 
 
 
 
 

7. Determine the molecular mass for each of the following:
 Circle your answer.  (5 points each)
 

 a)  (NH₄)₂C₂O₄                                     b)  Al(OH)₃
 
 
 
 
 
 
 
 
 
 

8. Determine the empirical formula for a compound from the information given:  The compound analyzes as 49.99 % C, 5.61 % H, and 44.40 % O.  (10 points)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

9. Balance the following equations by inspection.     (20 points)
 
 

_____ La₂O₃ + _____ H₂O  ------>  _____ La(OH)₃
 
 

_____ Pb(NO₃)₂  + _____ H₃AsO₄  ------>  _____ PbHAsO₄ + _____ HNO₃
 
 

_____ PCl₅ +  _____ H₂O   ------>  _____ H₃PO₄ +  _____ HCl
 
 

_____ Cu  +  _____ AgNO₃    ------>   _____ Cu(NO₃)₂   +  _____ Ag
 
 

_____ HCl + _____ Mg₃N₂  ------>  _____ NH₄Cl + _____ MgCl₂
 

10. Determine the mole ratio for each of the following: (8 points)

 a)  C₃H₈
 

 b)  CO₂
 

 c)  N₂O₅
 

 d)  CoCl₃