Ch 15 Review Sheet Questtions 8-12

8. Write the formula for ppm?

_grams of solute_    x  10⁶   = ppm

grams of solution

9.  A chemist dissolves 18.91 g of AgNO₃ in a 500.0 mL volumetric flask, then adds distilled water to the calibration mark.  Determine the molarity of the solution.  Show your work.

           

1)  Ag = 107.9                                                 3) 500 mL/1000ml = 0.500 L

      N  =  14.01

        O₃ = 48.00                                               4) M = mol/Liters

               169.91 g/mol                                     0.111 mol   = 0.223 mol/L

                                                                                      0.500 L

2) 18.91/169.91 = 0.111 mol AgNO₃

10. In #9, which is the solvent?  Which is the solute?

solvent: distilled water   solute: AgNO₃

11. If you add a tablespoon of NaCl to water, what will it do the boiling temperature?

What will it do the freezing temperature of the solution?

            Boiling point raises

            Freezing point lowers

12. You have 255 mL of a 3.02 M KCl solution.  You add 375 mL of water.  What is the new molarity of the solution?  Show your work.

 V₂ = 255 mL                                       V₁  = 255 mL + 375 mL = 630. mL

M₂ = 3.02 mol/L KCl                           M₁ = ?

M₁ = V₂M₂      =          255 mL x 3.02 mol/L  =  1.22 mol/L

                        V₁                                           630. mL