Problem Set 6.8:       Solution Review

Complete all questions on your own sheet of paper. Be careful to use correct significant figures and units for any calculation problems. For all chemical equations use phase subscripts.

Concentration

1.     Calculate the concentration of the solution formed when 23.61 g of sodium phosphate is dissolved in 475.0 cm3 of water. 0.3032 M

2.     What volume of water is needed to dissolve 85.8 g of silver nitrate to make a 2.650 M solution? 0.191 L   or  191 mL

3.     What mass of magnesium sulphate is needed to make 1500 mL of a 2.45 M MgSO4 solution? 442 g

4.     Calculate the concentration of the solution formed when 59.78 g of ammonium hydroxide is dissolved in 856.0 cm3 of water. 1.992 M

5.     What volume of water is needed to dissolve 150.8 g of lithium borate to make a 9.46 M solution? 0.200 L   or  200 mL

6.     What mass of mercury (II) iodide is needed to make 1350 mL of a 3.17 M HgI2 solution? 1.94  x  103 g  or  1.94 kg

7.     Calculate the concentration of the solution formed when 520.3 mg of oxalic acid dihydrate is dissolved in 26.0 cm3 of water. 0.159 M

8.     How many moles of (NH4)2CO3 are contained in 2.40 L of a 0.899 M solution? 2.16 moles

9.     What is the number of moles of chemical found in 20.0 L of 4.80 M solution? 96.0 moles

10.  Determine the volume of 1.339 M KBr solution that contains 5.25 moles of solute. 3.92 L

Dilutions

1.     A 350.0 mL solution is diluted to 1.965 L. At this dilution, it has a concentration of 0.97 M. What was the original concentration? 5.4 M

2.     Calculate the resulting concentration when 460.0 mL of 6.58 M ammonium phosphate solution has 650.0 cm3 of water added to it. 2.73 M

3.     What volume of water is needed to dilute 275.0 mL of 7.95 M AlCl3 solution to a concentration of 0.820 M? 2.39 L

4.     A 10.00 mL solution is diluted to 680.0 mL. Calculate the original concentration if it now has [ ] = 0.055 M? 3.7 M

5.     Calculate the resulting concentration when 0.980 L of 7.985 M sodium phosphate solution has 2000.0 cm3 of water added to it. 2.63 M

6.     What volume of water is needed to dilute 100.0 mL of 8.06 M BaCl2 solution to a concentration of 0.0975 M? 8.17 L

Ion Concentration Calculations

1.     What is the concentration of each ion in a 10.5 M sodium silicate solution? [Na+] = 21.0 M, [SiO32-] =  10.5 M

2.     What is the concentration of each ion in the solution formed when 94.5 g of nickel (III) sulphate is dissolved into 850.0 mL of water? [Ni3+] = 0.549 M, [SO42-] =  0.823 M

3.     If 3.78 L of 0.960 M calcium fluoride solution is added to 6.36 L of 0.550 M ammonium fluoride solution, what is the resulting concentration of each ion? [Ca2+] = 0.358 M, [NH4+] = 0.345 M, [F-] =  1.06 M

4.     What is the concentration of each ion in a 5.55 M zinc glutamate solution? [Zn2+] = 5.55 M, [C5H8NO4-] =  11.1 M

5.     What is the concentration of each ion in the solution formed when 94.78 g of iron (III) sulphate is dissolved into 550.0 mL of water? [Fe3+] = 0.8618 M, [SO42-] =  1.293 M

6.     If 6.25 L of 0.560 M sodium bromide solution is added to 3.45 L of 0.940 M magnesium bromide solution, what is the resulting concentration of each ion? [Na+] = 0.361 M, [Mg2+] = 0.334 M, [Br-] =  1.03 M

Dissociation Equations: Write dissociation or dissolving equations for any chemicals that are dissolved in water

1.     HCl (aq)                  HCl (aq)                             à            H+ (aq)                     +          Cl- (aq)   

2.     Na2S (s)                  Na2S (s)                             à        2 Na+ (aq)              +          S2- (aq)

3.     Al(CH3COO)3 (s) Al(CH3COO)3 (s)       à        Al3+ (aq)                 +          3 CH3COO- (aq)

4.     MgBr2 (s)               MgBr2 (s)                     à        Mg2+ (aq)               +          2 Br - (aq)

5.     Na2CO3 (s)             Na2CO3 (s)                  à        2 Na+ (aq)              +          CO32- (aq)

6.     C12H22O11 (s)         C12H22O11 (s)               à        C12H22O11 (aq)    (molecular compounds do not dissociate)

7.     K3PO4 (s)               K3PO4 (s)                     à        3 K+ (aq)                 +          PO43- (aq)

8.     CH3OH (l)              CH3OH (l)                   à        CH3OH (aq)

Net Ionic Equations: Write chemical equations, total ionic equations and net ionic equations for each reaction (assume that all reactions occur)

1.     Magnesium metal is placed in hydrochloric acid

            Mg (s)            +   2 HCl (aq)                                 à        MgCl2 (aq)             +        H2 (g)

            Mg (s)    +  2 H+ (aq) +  2 Cl- (aq)                       à        Mg2+ (aq)  +   2 Cl - (aq)  +  H2 (g)

            Mg (s)           +  2 H+ (aq)                                      à        Mg2+ (aq)       +                H2 (g)

2.     Silver metal is placed in zinc nitrate solution

            2 Ag (s)            +   Zn(NO3)2 (aq)                                à        Zn (s)     +        2 AgNO3 (aq)

            2 Ag (s)     +   Zn2+ (aq)   +  2 NO3 - (aq)               à        Zn (s)       +        2 Ag+ (aq) +  2 NO3 - (aq)

            2 Ag (s)            +    Zn2+ (aq)                                           à        Zn (s)     +        2 Ag+ (aq)

3.     Barium chloride solution is added to lead (II) nitrate solution.

            BaCl2 (aq)             +   Pb(NO3)2 (aq)                         à        PbCl2 (s)            +            Ba(NO3)2 (aq)

            Ba2+(aq) + 2 Cl-(aq) +  Pb2+(aq) + 2NO3 -(aq)      à        PbCl2 (s) + Ba2+ (aq) + 2 NO3 - (aq)

            2 Cl- (aq)            +    Pb2+ (aq)                                        à        PbCl2 (s)

4.     Sulphuric acid is added to potassium hydroxide solution.

                  H2SO4 (aq)             +   2 KOH (aq)                                  à        2 H2O (l)           +        K2SO4 (aq)

            2 H+(aq) + SO42-(aq) +  2 K+(aq) + 2 OH -(aq)    à        2 H2O (l)  +  2 K+(aq)  +  SO42-(aq)

                                    H+(aq)   +   OH -(aq)                      à        H2O (l)

5.     Sodium carbonate solution is added to nickel (III) nitrate solution.

            3 Na2CO3(aq)            +   2 Ni(NO3)3 (aq)             à        Ni2(CO3)3 (s)   +         6 NaNO3 (aq)

6 Na+(aq) +3 CO32-(aq) +2 Ni3+(aq) +6NO3 -(aq)      à        Ni2(CO3)3 (s) + 6 Na+(aq) + 6 NO3 - (aq)

                        3 CO32-(aq)            +    2Ni3+(aq)               à        Ni2(CO3)3 (s)

6.     Aqueous chlorine is added to sodium bromide solution.

Cl2 (aq)                   +   2 NaBr (aq)              à        2 NaCl (aq)          +      Br2 (aq)

            Cl2 (aq)    +   2 Na+ (aq) +  2 Br - (aq)      à            2 Na+ (aq) +  2 Cl - (aq)  +  Br2 (aq)

            Cl2 (aq)                   +   2 Br - (aq)                à        2 Cl - (aq)             +      Br2 (aq)

7.     Nitric acid is added to aluminum hydroxide solution.

                  3 HNO3 (aq)       +   Al(OH)3 (aq)                       à        3 H2O (l)              +            Al(NO3)3 (aq)

3 H+(aq) + 3 NO3-(aq) +  Al3+(aq) + 3 OH -(aq)   à        3 H2O (l) + Al3+(aq) + 3 NO3-(aq)

                                                 H+(aq)   +   OH -(aq)      à        H2O (l)

8.     Ammonium sulphide solution is added to gold (I) nitrate solution. 

            (NH4)2S (aq)           +   2 AuNO3 (aq)                  à        Au2S (s)               +      2 NH4NO3 (aq)

            2 NH4+(aq) + S2-(aq) + 2 Au+(aq) +2 NO3 -(aq)    à        Au2S (s)  + 2 NH4+(aq) +  2 NO3 -(aq)

                                                S2-(aq) + 2 Au+(aq)        à        Au2S (s) 

Solution Stoichiometry

1.     Copper metal is placed in a solution of silver nitrate. Determine the mass of Ag produced when 162.3 mL of 1.54 M copper (II) nitrate solution is formed at the end of the reaction. 53.9 g

2.     What is the mass of a calcium hydroxide needed to neutralize 70.0 mL of 1.46 M sulphuric acid? 7.57 g

3.     What [ ] of the solution formed when 20.4 g of magnesium bromide is dissolved in 200.0 cm3 of water and then reacted with Cl2 gas?  0.554 M

4.     What is the concentration of the solution formed when 91.23 g of zinc metal is reacted with 950.0 cm3 of 1.25 M hydrochloric acid? What is the volume of hydrogen gas (at STP) that is evolved in the same reaction? 0.468 M and 31.2 L

5.     What volume of 2.33 M of sodium hydroxide solution is needed to fully neutralize 1000.0 cm3 of 17.6 M hydrobromic acid? 7.55 L

6.     What volume of 1.35 M of strontium hydroxide solution is needed to fully neutralize 710.0 cm3 of 1.663 M nitric acid? 0.437 L

7.     What is the concentration of 620.0 mL of a potassium hydroxide solution is used to neutralize 330.0 cm3 of 3.45 M sulphuric acid? 3.67 M

8.     What is the concentration of 1942.0 mL of a sulphuric acid solution is used to neutralize 1.56 L of 14.2 M ammonium hydroxide solution? 5.70 M

9.     What is the mass of precipitate formed when 321.0 mL of 0.490 M K3PO4 is added to 470.0 mL of 1.700 M Pb(NO3)2 solution? 63.7 g

10.  What is the mass of precipitate formed when 325.0 mL of 3.10 M K2S is added to 100.0 mL of 1.52 M Ni(NO3)3 solution? 16.0 g

Titrations Calculations

1.     A 25.00 mL sample of nitric acid is placed in a 150 mL Erlenmeyer flask. Phenolphthalein is added to the solution. Sodium hydroxide solution was added from a burette until there was a faint pink color. If [NaOH] = 2.004 M, determine the concentration of nitric acid given the following burette readings:

                                                Burette final    =          38.10 mL                                             2.604 M

                                                Burette initial  =            5.62 mL

 

2.     A 50.00 mL sample of 0.9956 M sodium hydroxide solution is placed in a 150 mL Erlenmeyer flask. Hydrochloric acid was added from a burette until the endpoint had been  reached. Determine the [HCl ] given the following burette readings:

                                                Burette final    =          32.76 mL                                             3.612 M

                                                Burette initial  =          18.98 mL

 

3.     The following data was obtained during the titration of 0.1058 M sodium hydroxide with a 10.00 mL aliquot of sulphuric acid:

 

Trial 1

Trial 2

Trial 3

Burette Final Reading

26.05 mL

48.52 mL

33.78 mL

Burette Initial Reading

12.46 mL

34.94 mL

20.22 mL

Vol. of NaOH Added

 

 

 

 

Use the above information to determine the concentration of the acid.                           0.0719 M