Showing posts with label cell chemistry. Show all posts
Showing posts with label cell chemistry. Show all posts

Monday, May 9, 2011

What is K? (A Mind-Map Style Explanation)


As I had mentioned in the introductary post to this blog, I had a real hard time figuring out what "K" meant until it was finally revealed to me. Even then, I pretty much didn't have the right answer until I took the professor's advice and made a flowchart of what "K" actually is. Here below is a hand-drawn mind-map of K, and represents much of what we learned in Chem II. I apologize in advance for the sloppy penmanship. Part of the assignment required that I write it by hand, rather than make the chart on computer.
Click on image for the Large Version


As you can see, K, as it applies to most of second semester inorganic chemistry, is a thermodynamic constant, and is largely the distilled essence of everything from solubility to electrochemistry, and most points in-between. Despite the fact we were, throughout the semester, educated on the values of Kc, Ka, Ksp, and many other constants, they all are simply different aspects of K. The value in learning this is in finding out exactly how a constant comes into being. I'm sure most of you by now have encountered the Ideal Gas Constant, or Faraday's Constant, Coulomb's Constant. or even Avogadro's Number, and wondered "that's great, and all, very useful stuff to know, but how do these constants come about in the first place?"

Unlike the ones I mentioned, K is a dynamic constant, in that it is not a number that will always be the same. It changes depending on the values fed to it, but the formula, the product of the concentration of right-hand side of the equation, divided by the product of concentrations of the left-hand side of the equation, helps us to understand where constants come from. In these instances, we are developing our own constants each time. It is through this process we begin to unlock the methodology that the giants before us used to establish the static constants (the numbers that are always the same) by applying very much the same principles, using slightly more advanced math, and many, many trials.

This concept was at first so frustrating for me, and later so inspirational, that it resulted in the creation of this blog, and hence, the name, The Daily Constant. It helps us each to remember that it is you who hold the future of scientific breakthroughs in your hand, not those who came before you. They hold the past, but it is up to you to come up with the constants others will use for ages to come, and to unlock the knowledge and additional mysteries it brings.

Saturday, May 7, 2011

Chem II: Final Exam Review (Part 4/4)


Nuclear Chemistry

1.       What is the A,X,Z of an atom? A = Mass Number, X = Element, Z = Protons (Atomic #)
2.       What are the 5 types of spontaneous radioactive decay?

Name & Sym
Particle
Formula
Z#
A#
Reason
Alpha α
42He
-
-2
-4
Z > 83
Beta β-
0-1e
10n --> 11p + 0-1e
+1
0
N/Z too large
Positron β+
0+1e
11p --> 10n + 0+1e
-1
0
N/Z too small
Electron Cap. (EC)
X rays
11p + 0-1e --> 10n
-1
0
N/Z too small
Gamma  γ
00 γ
-
0
0
Excited

3.       What is the highest non-radioactive atomic number?      - 83
4.       What are the magic numbers of stability?
a.       For Protons?      2, 8, 20 , 28, 50, 82
b.      For Neutrons?   2, 8, 20, 28, 50, 82, 126 (maybe 114)
c.       What is the general guideline for stability?           - Even #’s more stable than odd #’s.

5.       What is a Curie (definition and constant)? Nuclear disintegrations per unit time occurring in a radioactive material.  Ci = 3.7 x 1010

6.       What is the formula for finding Half-Life?              T1/2 = 0.693
k

7.       What is the formula for finding the Rate of Decay?           Rate = kNt


Organic Chemistry

1.       What are the three basic types of Hydrocarbons?
a.       How reactive are they?
b.      What types of reactions are they typically capable of?
Saturated
Not very reactive
Combustion w/Oxy or Halo
Unsaturated
Very reactive
Addition Reaction, Combustion
Aromatic
Not very reactive
Replacement Reactions


2.       What are the families of each of the three basic types of Hydrocarbons?
a.       What group(s) of carbon families does each include?
b.      What type of electron bond(s) exists for each family?
c.       What is the general formula for each family?

Saturated
Alkanes
C-C chains
CnH(2n+2)
Saturated
Cycloalkanes
C-C rings
CnH(2n)
Unsaturated
Alkene
C=C chain
CnH(2n)
Unsaturated
Alkyne
CC chain
CnH(2n-2)
Aromatic
Benzene
C-C/C=C rings
C6H6


3.       What are the first ten alkanes?
a.       CH4        methane
b.      C2H6      ethane
c.       C3H8      propane
d.      C4H10   butane
e.      C5H12   pentane
f.        C6H14   hexane
g.       C7H16   heptane
h.      C8H18   octane
i.         C9H20   nonane
j.        C10H22 decane

4.       What are the first four alcohols and their chemical formulas?
a.       CH3OH                                  Methanol
b.      CH3CH2OH                          Ethanol
c.       CH3CH2CH2OH                  Propanol
d.      CH3CH2CH2CH2OH          Butanol

5.       What is the difference between a primary, secondary, and tertiary alcohol?
a.       Primary has one Carbon group attached to the carbon attached to the OH group.
                                                               i.      eg.   C-C-C-OH
b.      Secondary has two Carbon groups attached to the carbon attached to the OH group.
c.       Tertiary has three.

6.       Name the following compounds:




7.       What is an Aldehyde (and its suffix)? Suffix = “al”
a.       What is its R-group positioning?

b.      What is its molecular tail?             -CHO
c.       Draw Formaldehyde (methanal)

8.       What is a Ketone (and its suffix)? Suffix = “one”
a.       What is its R-group positioning?

 
b.      What is its molecular tail?  =O

c.       Draw acetone (propone)


9.       What would happen if litmus paper were dipped into an Amine?
a.       It would turn red litmus paper blue.





the end