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Chemistry LibreTexts

Acids and Bases 1 (Worksheet)

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    3135
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    Work in groups on these problems. You should try to answer the questions without referring to your textbook. If you get stuck, try asking another group for help.

     
    H-Containing Molecules  HO- & -OH Containing Molecules
    Formula Red Litmus Blue Litmus Formula Red Litmus Blue Litmus
    HCl Red Red  HClO (HOCl) Red Red
     CH4 Red Blue Al(OH)3 Blue Blue
     NaH Blue Blue  CH3OH Red Blue
     HI Red Red  H3PO4 Red Red
     H2O Red Blue  CH3CH2OH Red Blue
     SrH2 Blue Blue LiOH Blue Blue
     H2S Red Red HNO2 Red Red
     KH Blue Blue HCOOH Red Red
     HF Red Red Be(OH)2 Blue Blue
     HBr Red Red H2SO3 Red Red
     CH2O Red Blue  OCHCH2OH Red Blue

    1.    Which compounds from the list are acidic?




    2.    Which compounds from the list are basic?




    3.    Which compounds from the list are n?


    Observation Set 2

    Improving upon the capabilities of indicator paper, pH meters are able to quantitatively measure the acidity of a solution. All pH values that follow are measurements of 0.010 M solutions. For ions, the values represent solutions of the sodium salts of the ion. Drawing Lewis structures will help you see the structure–pH relationship more clearly. If uncertain of the atom attachments ask your instructor.

    Species pH Species pH Species pH
     HClO4  2.00 SO32–  9.60 H2S 4.50
     H2SO4  2.00 HCl  2.00 HPO42– 9.60
     H3PO4  2.24 H2PO4  4.60 HBr 2.00
     ClO 9.73  HI 2.00 SO42–  7.00
     ClO4  7.00 H2SO3 2.18 PO43–  11.89
     HSO4  2.88 CH3COOH 3.37 NaOH  12.00
     HClO  4.73 HS 9.50 HNO2 2.72
     HSO3  4.60 H2O 7.00 Cl 7.00

    4.    Rank the acids by increasing acid strength:





    5.    Rank the bases by increasing base strength:





    6.    Are the anions (conjugate bases) of strong acids: basic, neutral or acidic?





    7.    Are the anions (conjugate bases) of weak acids: basic, neutral or acidic?


    Observation Set 3

    The concepts of partial atomic charges and relative electronegativities can be used to predict the acid–base properties of molecules. These partial hydrogen charges (δ+) have been calculated based on the electronegativities of the atoms.

     

    Species H's Charge (δ+) Species H's Charge (δ+)
    CH4 +0.012 H2PO4 +0.36
    HClO +0.34 H2O +0.26
    HSO3 +0.28 HSO4 +0.30
    H2SO4 +0.53 HClO4 +0.57
    CH3COOH +0.35 (OH) CH3OH +0.30 (OH)
      +0.099 (CH) +0.050 (CH)  
    H3PO4 +0.36 H2S +0.30
    Al(OH)3 +0.23 HPO4 +0.26

     

    8.    Rank the following in order of increasingly positive hydrogen charge:

        a)  HClO2, HCl, CH4, H2O, HClO

     

    <        <        <        <

     

        b)  OClOH, ClOH, IOH, O3ClOH, O2ClOH

     

    <        <        <        <

     

    9.    Rank the acids by increasing acid strength:

     

    10.    Explain in terms of the partial charge on hydrogen why NaOH is a base, HClO is a weak acid and HClO4 is a strong acid.        

     

    11.    Why is HCl a strong acid and HClO a weak acid?

     

    12.    Why are HCl and HClO4 both strong acids?

     

            

     

     

     

    13.     For each of the reactions below, classify the reactants as an acid or a base and the products as the conjugate acid or conjugate base.

     

        a)  CN  +  H2O  ->  HCN  +  OH

     

        b)  B(OH)3  +  2 H2O ->  B(OH)4  +  H3O+

     

        c)  H2O  +  HCl  ->  H3O+  +  Cl

     

        d)  4 LiH  +  AlCl3  ->  LiAlH4  +  3 LiCl

     

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