confused2021

Hello. My question is as follows :Calculate the pI of Leucine pKa (carboxyl) = 2.4; pKa (amino) = 9.6; What is the ratio of COO- : COOH at pH 3.4? For pI I get 6 (9.6 + 2.4/2 = 6). I am having great difficulty with the 2nd part of the question. I get 63.8% COO-: 36.2% COOH. I deduced this since 50% is dissociated at pH2.4 and 100% is dissociated at pH6. There are 3.6 units from 2.4 to 6. Since it is one above 2.4, I divided 1/3.4 and multiplied it by 50 to get 13.8%. This added to the 50% dissociated at 2.4pH equals 63.8% dissociated and 36.2% not dissociated. Any help on how to reason this out to get the right answer would be greatly appreciated!!!!

I am having difficulty with the following problem: If you dissolve 360mg glucose (Formula Weight: 180.16g/mole) in 5mL of water: 1.What is the concentration of glucose in mM and µM? I got 360 mg x 1mole/180.16 g = .002 moles .002 moles x .005L = 1 x 10^-5 M x 1 x10^3 mM/1M = 1 x 10^-3 mM glucose 1 x 10^-3 mM x 1x 10^-3micromolar/1mM = 1 x 10^-5 micromolar glucose 2.If you take 5mL of this solution and dilute it to 500mL what is the concentration of the glucose in the resulting solution in µM? I used c1v1=c2v2 (1 x 10^-5 micromolar)(5mL) = (C2)(500 mL) = 1 x 10 ^-7 microMolar 3.How many nanomoles of glucose are present in 10mL of the diluted solution? I am having difficulty with number 3. Can anyone tell me if numbers 1 and 2 are right and also how I can solve number 3. Any input will be greatly appreciated!!!!

Thanks again for your help, guys!!! I greatly appreciate it!!! If anyone has time, I would greatly appreciate it if you could check my answers. I am going to go over the worksheet again to make sure that I did all 15 questions (except for question 5 which I know see was a typo). If anyone could help and let me know if any one of the answers seem wrong, I would greatly appreciate it!!!! Conversion Sheet.pdf

Thanks for all your help!!! The worksheet says to put everything in scientific notation. Therefore if I get an answer, for example, in question 1 as 1.5, would I write 1.5 x 10^0? Any input on this would be greatly appreciated!!!! Conversion Sheet_pp xi.pdf

Thank you two individuals very much for your help! What I wrote is pretty much the whole question. It is a worksheet where I am given 4.5 ng and I am supposed to convert it to micrograms/microliter. I have attached the worksheet. It is question number 5. Am I correct in assuming that there is perhaps no answer snice you cannot covert a concentration to a concentration in a volume? Could it perhaps have been a typo? Do I write "Not Applicable" as the answer? Question 5.pdf

I am confused on how to convert 4.5 nanograms to micrograms per microliter. When I make the conversion do I have to use any calculations to get microliters. Using the fact that there are 1 x 10^-3 micrograms in 1 nanometer I get 4.5 x 10^-3 micrograms per microliter. Is this the correct answer? Any assistance from anyone would be greatly appreciated!!!!