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pH: Flashcards

Revise pH, pOH, Kw and pH calculations for strong acids and bases.

10 cardsIntermediate

10 cards

  1. Question
    What is the definition of pH?
    Answer

    pH=−log⁡[HX3OX+]\text{pH} = -\log[\ce{H3O+}]

  2. Question
    At 25 °C, what pH values are acidic, neutral and basic?
    Answer

    Below 7 acidic, exactly 7 neutral, above 7 basic.

  3. Question
    What is KwK_\text{w} at 25 °C?
    Answer

    Kw=[HX3OX+][OHX−]=1.0×10−14K_\text{w} = [\ce{H3O+}][\ce{OH-}] = 1.0 \times 10^{-14}

  4. Question
    What is the relationship between pH and pOH at 25 °C?
    Answer

    pH + pOH = 14.00

  5. Question
    How many times more HX3OX+\ce{H3O+} does a pH 3 solution have than a pH 6 solution?
    Answer

    1000 times (10310^3): each pH unit is a factor of 10.

  6. Question
    What is the pH of 0.010 M HCl?
    Answer

    −log⁡(0.010)=2.00-\log(0.010) = 2.00

  7. Question
    What is the pH of 0.0010 M NaOH?
    Answer

    pOH = 3.00, so pH = 14.00 − 3.00 = 11.00

  8. Question
    How do you find [HX3OX+][\ce{H3O+}] from the pH?
    Answer

    [HX3OX+]=10−pH[\ce{H3O+}] = 10^{-\text{pH}}

  9. Question
    What is [OHX−][\ce{OH-}] in 0.020 M Ca(OH)X2\ce{Ca(OH)2}?
    Answer

    0.040 M: each formula unit releases two OHX−\ce{OH-} ions.

  10. Question
    How many decimal places should a pH have?
    Answer

    As many as the significant figures in the concentration (0.050 M → pH 1.30).