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Some Equilibrium Problems

  1. Apr 28, 2005 #1
    Basic Grade 12 Chemistry questions:

    1. Which of the following salts act like acids when applied to soil?

    a. [tex] BeCl_2 [/tex]
    b. [tex] KF[/tex]
    c. [tex] FeI_3 [/tex]
    d. [tex] LiNO_3 [/tex]
    e. [tex] KClO_4 [/tex]

    I believe the answer is c, any confirmation?

    2. Which of the following salts act like bases when applied to the soil?

    a. [tex] NaHSO_4 [/tex]
    b. [tex] KNO_2 [/tex]
    c. [tex] CaCl_2 [/tex]
    d. [tex] LiNO_3 [/tex]
    e. [tex] KClO_4 [/tex]

    I believe the answer is b, and either a or b, but again, my reasoning is not solid =( would appreciate an explanation

    3. All of the following are strong electrolytes in aqueous solution EXCEPT:
    a. acetic acid (HC2H3O2)
    b. sodium acetate (NaC2H3O2)
    c. ammonium acetate (NH4HC2H3O2)
    d. sodium hydroxide (NaOH)
    e. hydrochloric acid (HCl)

    I'm pretty sure the answer is either a or b. I understand that electrolyte means strong dissociation in water; with positive and negative ions that are able to conduct electricity. (Same thing like the self-ionization of water, where it ionizes very slightly into positive hydronium ions and negative hydroxide ions) I know that acetic acid is a relatively weak acid, and sodium acetate dissociates... I guess, but does Na+ being neutral have anything to do with it? I'd have to go down to a hunch and say acetic acid because it's a weak acid.

    4. Which solution has the highest pH?

    a. 0.1 M Hydrochloric acid
    b. 0.1 M [tex] NH_3 [/tex]
    c. 0.1 M [tex] Na_2NO_2 [/tex]
    d. 0.1 M [tex] AlCl_3 [/tex]
    e. 0.1 M [tex] CH_3COOH [/tex]

    I'm sure that the answer is either b or c. I'm looking for the least acidic, and most basic compound. I think it is c because when it breaks up into ions, the NO2 has a more negative charge, not sure if this is correct: Na^2+ and 2NO2- so therefore it c will want to draw H protons to itself because of its - charge.

    5. The value of [tex]K_w [/tex] increases as the temperature of water is raised. What effect will increasing the temperature have on its pH?

    I'm kind of stumped on this one. I know that increasing the temperature will increase the value of Kw. (side note: why, exactly?) but do the concentrations of H+ and OH- grow equally? I'm thinking it either lowers the pH (more acidic) or stays the same. I'm really not sure about this one and I'm worried because I can't figure it out. =(

    That's all for now, I'm sorry if these questions seem trivial to you, but I really tried to think them through!

    -Art
     
    Last edited: Apr 28, 2005
  2. jcsd
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