San Jacinto College - CHEM 1311

Chem 1311: Practice Problems

Chapter 4: Chemical Reactions in Aqueous Solution

1)Which of the following would you expect to be strong electrolytes when placed in water?

1. 1. NH4Cl                           
   2. MgBr2                          
   3. HCl                                
   4. CH3COOH (or HC2H3O2)
   5. CH3OH                         
   6. NH3                              
2. Classifying acids and bases as strong or weak?

1. 1. LiOH                              
   2. HC2H3O2                    
   3. HBr                                
   4. HNO2                           
   5. HNO3                           

1. 6. HF                                  
   7. H2SO4                          
   8. Ba(OH)2                      
   1. Fe(OH)3                      
   10. Mg(OH)2                    

3. Obtaining the oxidation number for the element noted in each of the following:

a)            Ga() in Ga2O3

b)            Br() in KBrO4

c)            Nb() in NbO2

d)            Mn() in K2MnO4

e)            P() in Na3PO4

f)             N() in NH2-

g)            I() in IO3-

h)            H() in H2

i)             Cl() in HClO4

j)             As() in H2AsO3-

k)            Cr ()in CrO42-

l)             Br() in BrCl4

m)          Si() in SiCl4

n)            H() in BaH2

o)            Ga() in Ga(OH)3

p)            Cr() in Cr2(SO4)3

4. Balancing simple Oxidation-Reduction Reactions by the half-reaction method.
   1. Mg(s) + N2(g) → Mg3N2(s)
   2. CuCl2(aq) + Al(s) → AlCl3(aq) + Cu(s)
   3. Cr³⁺(aq) + Zn(s) → Cr(s) + Zn²⁺(aq)

5. Molarity Calculation
   1. A sample of 0.0512 mol of iron(III) chloride, FeCl3, was dissolved in water to give 25.0 mL of solution. What is the molarity of the solution?  (4.67)

1. 2. A sample of NaNO3 weighing 0.38 g is placed in a 50.0 mL volumetric flask. The flask is then filled with water to the mark on the neck, dissolving the solid. What is the molarity of the resulting solution?

(MW of NaNO₃ = 85.00            ^g )

1. 3. An experiment calls for the addition to a reaction vessel of 0.184 g of sodium hydroxide, NaOH, in aqueous solution. How many milliliters of 0.150 M NaOH should be added? (MW of NaOH = 40.0 g/mol)

solution when the flask is filled to the mark with water? How many gram of NaCl is this?