pH and pOH Worksheet - Answer Key

 

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  1. What is pH?

    pH is simply a convenient way to describe the acidic character of  a solution.

     

     

  2. How do you solve for pH?

    pH = – log [H+]

     

     

  3. What do the following values of pH indicate about sol’n acidity/basicity?
    1. pH = 7

      The solution is neutral.                                                                            
    2. pH > 7

      The solution is basic (alkaline).
    3. pH < 7

      The solution is acidic.

       

       

  4. What are the rules of significant figures when solving for pH?

    On the pH scale, only number after the decimal are considered significant. 

     

     

  5. If [H+] = 1.0 x 10-7 M at 25oC, what is the pH?

    pH = 7.00
                          

     

     

  6. What is pOH?

    pOH is simply a convenient way to describe the basic character of  a solution.

     

     

  7. How do you solve for pOH?

    pOH = – log [OH]

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  9. How do pH and pOH relate?

    pH + pOH = 14
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  11. What do the following values of pOH indicate about sol’n acidity/basicity?
    1. pOH = 7

      The solution is neutral.    
    2. pOH > 7                                                                               

      The solution is acidic.
    3. pOH < 7

      The solution is basic.

       

       

  12. Calculate the pH for a 1.08M sol’n of HNO3.

    pH = -log (1.08) = -0.333
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  14. Calculate the pH for a 1.00 M sol’n of HF.   (Ka = 7.2 x 10-4)   

    pH = 1.569
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  16. A 10.0 mL sample of HCl has a pH = 2.000.  What volume of water must be added to change pH to 4.000?

    990 mL water
  17. Calculate the pH of a 5.0 X 10-4 M NaOH sol’n.

    pH = 10.70
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  19. Calculate the mass of HONH2 required to dissolve in enough water to make 250.0 mL of sol’n having a pH = 10.00  (Kb = 1.1 x 10-8)

    7.50 g of HONH2 required
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  21. The pH of a 1.00 x 10-2 M solution of HOCN is 2.77 at 25oC.  Calculate Ka of HOCN from this result.

    Ka = 3.5 x 10–4
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  23. Calculate the pH of a 0.30M C2H5NH2 solution.  (Kb = 5.6 x 10-4)

    pH = 12.11