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19 minutes ago, twslhs20 said:

A single extraction with 100 mL of CHCl3 extracts or removes 88.5% of the weak acid, HA, from 50 mL of aqueous solution. What is the partition coefficient, K, for HA at a pH = 3.00? The Ka for HA is 3.5 x 10-5.

A single extraction with 100 mL of CHCl3 extracts or removes 88.5% of the weak acid, HA, from 50 mL of aqueous solution. What is the Distribution coefficient, D, for HA at a pH = 3.00? The Ka for HA is 3.5 x 10-5.

 

1. So since the pH < Ka, it makes sense that we're able to extract HA. Since the partition coefficient is concentration ratio and the volumes are different, we split it out and since I'm lazy assume 100 mg of HA.

Kp = (Conc in Chloroform)/(Conc in Water) = [(88.5 mg)/(100 mL)]/[(11.5 mg)/(50 mL)]. Units are the same so they cancel out.

 

2. Distribution is pH-dependent where D = [(Kp)*(H+ Conc)]/[(Ka+(H+ Conc)]

pH of 3 gives you an H+ conc of 10^-3 (Side note: Sorry this does not translate on a football forum without subscripts). You've got the KA from the problem and you've got the Kp from part 1.

 

That help?

Edited by ramssuperbowl99
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2 hours ago, ramssuperbowl99 said:

1. So since the pH < Ka, it makes sense that we're able to extract HA. Since the partition coefficient is concentration ratio and the volumes are different, we split it out and since I'm lazy assume 100 mg of HA.

Kp = (Conc in Chloroform)/(Conc in Water) = [(88.5 mg)/(100 mL)]/[(11.5 mg)/(50 mL)]. Units are the same so they cancel out.

 

2. Distribution is pH-dependent where D = [(Kp)*(H+ Conc)]/[(Ka+(H+ Conc)]

pH of 3 gives you an H+ conc of 10^-3 (Side note: Sorry this does not translate on a football forum without subscripts). You've got the KA from the problem and you've got the Kp from part 1.

 

That help?

That makes more sense. Really appreciate it.

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3 hours ago, twslhs20 said:

A single extraction with 100 mL of CHCl3 extracts or removes 88.5% of the weak acid, HA, from 50 mL of aqueous solution. What is the partition coefficient, K, for HA at a pH = 3.00? The Ka for HA is 3.5 x 10-5.

A single extraction with 100 mL of CHCl3 extracts or removes 88.5% of the weak acid, HA, from 50 mL of aqueous solution. What is the Distribution coefficient, D, for HA at a pH = 3.00? The Ka for HA is 3.5 x 10-5.

 

dog this **** was the source of all my frustration in life 2 years ago. switched my major cause i could never figure this stuff out. only classes i ever failed were the 2 chemistry classes i tried. 

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3 hours ago, jfinley88 said:

dog this **** was the source of all my frustration in life 2 years ago. switched my major cause i could never figure this stuff out. only classes i ever failed were the 2 chemistry classes i tried. 

Haha, Its not Easy. PChem  and Calculus are my last big hurdles to finish my degree. All the other classes are pud business classes. Just gotta grind 4 more weeks and I get a break.

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4 hours ago, jfinley88 said:

dog this **** was the source of all my frustration in life 2 years ago. switched my major cause i could never figure this stuff out. only classes i ever failed were the 2 chemistry classes i tried. 

Units.  I remember my teacher the first year I had a class was a ****** about units, and then I took it in college and I understood why.

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Anybody else ever have a hernia?  I had my first hernia repaired in April of 2017 and now I have another one that's gonna need to be repaired a year later.  I'd just ignore it, but they're really damn annoying, and I'm paranoid of it becoming serious. 

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1 hour ago, CWood21 said:

Units.  I remember my teacher the first year I had a class was a ****** about units, and then I took it in college and I understood why.

Yeah converting from mm to um, back to m and then to cm is a real pain in the arse.

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