General Chem ll Reflection

Throughout the semester I learned many valuable lessons, but the most important was never put off studying until the last few days before the test. That caused me to try to cram for the exams and not fully learn each concept. After looking over the exams at the questions I missed if I had spent more time looking over it I would have got a better feel of what the exam was over. And while looking over it, the problem wasn't as hard as I thought it was while I was taking the exam. The most challenging concept was the cell potential. The equation for the cell potential and standard cell potential always got mixed up when I was trying to solve a problem. My advice for future chem II students would be each day you learn something new go over it and work practice problems til you are comfortable with it. They will regret not doing this when it comes the end of semester. Also if there is an opportunity for bonus, do it!

Answer to classmates problem

What is the silver concentration in a solution prepared by mixing 500mL of .500M silver nitrate with 400mL of .600M sodium chromate? Given that the ksp of silver chromate 1.2x10^-12


500mL of .500 M silver nitrate
400mL of .600M sodium chromate

The first step that needs to be done is balance the reaction.


2Ag+ (aq) + CrO4^2-    --->   Ag2CrO4

The ratio of the reaction is 2:1


mol Ag+ =           .500 mol Ag+                       500 mL                            1L
                          _____________          X                               X        ___________     = .25 mol Ag+
                                     L                                                                        1000 mL 


mol CrO4^2- =      .600 mol CrO4^2-               400mL                      1L
                             ________________      X                         X        _______          = .24 mol CrO4^2-
                                           L                                                             1000 mL


1/2 (.25 mol Ag+) < .24 mol CrO4^2-
Silver ion is the limiting reactant.


Then use ICE equation

2Ag+(aq)  +  CrO4^2-(aq)   ----->   Ag2CrO4(s)
  .25                .24
-.25              -(.25/2)
__________________
0                    .115

Finding excess CrO4^2-

[CrO4^2-]excess=   .115mol CrO4^2-
                               _______________                            =         128 M CrO4^2-
                                (500+400) mL X 1/1000mL


Ag2CrO4(s)   <------> 2Ag=(aq)    +     CrO4^2-(aq)     Ksp= 1.2x10^-12
                                      0M                      .128
                                   + 2x                       +x 
                                __________________________
                                     2xM                   (.128+x)



Ksp=1.2x10^-12 = [Ag+]^2  [CrO4^2-] =  (2x)^2 (.128+x)

1.2x10^-12 = [Ag+]^2 (.128M)


[Ag+] =  (1.2x10^-12)  ^ 1/2
              ___________                          = 3.06 x 10^-6
              (.128M)

 *Couldn't find one big bracket for whole equation & all of it is raised to the half, not just the top.


My final answer is 3.06 x 10^-6

Hyaluronidase

Hyaluronidase

Structure:  Six Hyal sequences occur in the human genome, constituting a newly recognized family of enzymes.

 

Reactions: “By catalyzing the hydrolysis of hyaluronan, a constituent of the extracellular matrix (ECM), hyaluronidase lowers the viscosity of hyaluronan, thereby increasing tissue permeability. It is, therefore, used in medicine in conjunction with other drugs to speed their dispersion and delivery. Common applications are opthalmic surgery, in combination with local anesthetics.” “They have similar catalytic mechanisms that contrast markedly with the bacterial Hyals.” So the enzyme helps your body absorb medicines that are injected to your skin.

Rates: “It also increases the absorption rate of parenteral fluids given by hypodermoclysis, and is an adjunct in subcutaneous urography for improving resorption of radiopaque agents. Hyaluronidase is also used for extravasation of hyperosmolar solutions.”

Formula: C₂₄₅₅H₃₇₇₅N₆₁₇O₇₀₄S₂₁

Molecular weight: 53870.9 g/mol

REFERENCES

http://en.wikipedia.org/wiki/Hyaluronidase

http://www.3dchem.com/molecules.asp?ID=27

 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2547145/

 

 

Hyaluronidase

Hyaluronidase

Kelsey Feltner

Structure:

 

Reactions: “By catalyzing the hydrolysis of hyaluronan, a constituent of the extracellular matrix (ECM), hyaluronidase lowers the viscosity of hyaluronan, thereby increasing tissue permeability. It is, therefore, used in medicine in conjunction with other drugs to speed their dispersion and delivery. Common applications are opthalmic surgery, in combination with local anesthetics.” So the enzyme helps your body absorb medicines that are injected to your skin.

Rates: “It also increases the absorption rate of parenteral fluids given by hypodermoclysis, and is an adjunct in subcutaneous urography for improving resorption of radiopaque agents. Hyaluronidase is also used for extravasation of hyperosmolar solutions.”

Formula: C₂₄₅₅H₃₇₇₅N₆₁₇O₇₀₄S₂₁

Molecular weight: 53870.9 g/mol

REFERENCES

http://en.wikipedia.org/wiki/Hyaluronidase

http://www.3dchem.com/molecules.asp?ID=27

 

 

 

 

 

Picric acid - Kelsey Feltner

PICRIC ACID

IUPAC name: 2,4,6-Trinitrophenol

Structure:

 



Chemical formula & molecular weight g/mol: C₆H₃N₃O₇     229.1 g/mol                

Physical properties: Melting point- 122.5 °C     Boiling point-> 300 °C (Explodes)  Solubility in water-12.7 g/L

Intermolecular forces: Hydrogen bonding results in higher melting points and much higher boiling points. Picric acid is both a useful explosive compound and a precursor to other explosives.

References- http://en.wikipedia.org/wiki/Picric_acid
http://www.britannica.com/EBchecked/topic/455507/phenol
http://web.mit.edu/semenko/Public/Military%20Manuals/RogueSci-Mirror/explo/picric_acid.html