chemistry

the much used drug cocoaine is an alkaloid. Alkaloids are noted for their bitter taste, and indication of their basic properties. Cocaine, C17H21NO4 is soluble in water tot he extent of 0.17 g/100 ml solution, and a saturated solution has a pH of 10.08. What is the Kb for cocaine?

  1. 👍 0
  2. 👎 0
  3. 👁 157
asked by Symone
  1. Let's call cocaine something simple so as to save all that typing, say R3N.
    R3N + HOH ==> R3NH^+ + OH^-

    Kb = (R3NH^+)(OH^-)/(R3N)
    pH = 10.08, solve for pOH from
    pH + pOH = pKw = 14
    Then calculate OH^- from
    pOH = -log(OH^-). That will also be (R3NH^)+.
    For R3N, substitute the solubility in M = moles/L.
    0.17g/100 mL = 1.7 g/L and 1.7 is how many moles. moles = grams/molar mass
    Post your work if you get stuck.

    1. 👍 0
    2. 👎 0
    posted by DrBob222
  2. i got 3.2 for my pOH and 6.31x10^-4 for my [OH^-]. after this i am stuck and not sure where to go.

    1. 👍 0
    2. 👎 0
    posted by Symone
  3. You got what for pOH.
    pH + pOH = 14
    pOH = 14-pH = 14-10.08 and that isn't 3.2. When you obtain the correct value for OH^-, then substitute that for (OH^-) in the Kb expression. Substitute the same number of (R3NH^+). That leaves something to be substituted for (R3N) in the Kb expression.
    The problem tells you the solubility of cocaine is 0.17 g/100 mL. That is the same as 1.7 g/L. How many moles is that?
    1.7/molar mass cocaine = moles and that in 1L is M. Substitute that and solve for Kb.

    1. 👍 0
    2. 👎 0
    posted by DrBob222
  4. Kb= .0876???

    1. 👍 0
    2. 👎 0
    posted by Symone
  5. no.

    1. 👍 0
    2. 👎 0
    posted by DrBob222
  6. The answer is 8.5x10^-9

    1. 👍 0
    2. 👎 0
    posted by MK

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    The much-abused drug cocaine is an alkaloid. Alkaloids are noted for their bitter taste, an indication their basic properties. Cocaine C17H21O4N, is soluble in water the the extent of 0.17g/100 mL solution, and a saturated

    asked by Sev on August 9, 2009
  2. psychology

    At a restaurant,you bite into a stalk of broccoli and it tastes bitter to you.Your date it tastes just fine.You may have: A)a sensitivity to tastes of bitter and salty,whereas your date has an elevated taste for sweet and sour

    asked by vedrana on September 22, 2009
  3. psychology

    At a restaurant,you bite into a stalk of broccoli and it tastes bitter to you.Your date it tastes just fine.You may have: A)a sensitivity to tastes of bitter and salty,whereas your date has an elevated taste for sweet and sour

    asked by vedrana on September 22, 2009
  4. physiology help

    why do fetal pigs have sensory papillae for bitter taste on the tongue? i have no idea. maybe so they won't eat something bad? Since this is not my area of expertise, I searched Google under the key words "bitter taste function"

    asked by dave on May 29, 2007
  5. p

    on this question can you help me please thanks At a restaurant, you bite into a stalk of broccoli and it tastes bitter to you. Your date thinks it tastes just fine. you may have: A) a sensitivity to tastes of bitter and salty,

    asked by val on October 21, 2009
  6. Algebra

    An asthma medicine is to be prepared from an elixir with a drug concentration of 5 mg/mL and a cherry flavored syrup that is to be added to hide the taste of the drug. How much of each must be used to prepare 100 mL of solution

    asked by Serena on September 16, 2013
  7. Algebra

    An asthma medicine is to be prepared from an elixir with a drug concentration of 5 mg/mL and a cherry flavored syrup that is to be added to hide the taste of the drug. How much of each must be used to prepare 100 mL of solution

    asked by Serena on September 16, 2013
  8. science

    how does having a cold affect the sense of taste? Most of what we "taste" depends upon what we smell. A cold interferes with our sense of smell, so that our food doesn't taste very good then. Check this site for more details.

    asked by may on June 27, 2007
  9. economics in healthcare

    6. Calculate Herfindahl Index and Concentration Ratios for these markets. Drug Companies H.I. = ?, C.R. ? Health Care Providers: H.I.=? , C.R.= ? 2005 SOM 2005 SOM Drug Co1 18.8 HC Co 1 43.1 Drug Co2 17.9 HC Co 2 31.7 Drug Co3

    asked by cynthia on April 12, 2010
  10. senses, stimulus

    what is the stimulus of taste? do i just say when something touches your tongue. i don't know how to explain it. for smell, i put odors and chemicals. is that right? for vision, i put light, color, movement? i need help on taste,

    asked by david on January 21, 2007

More Similar Questions