Drawing and Interesting Graphs Using MS EXCEL --- by Ria Park

Since a graph represents the relationship between variables, sometimes a graph helps us to solve the density problem.

Density = Mass/Volume

Because a slope is equal to y/x(Rise-y over Run-x), the volume should be on x-axis. On the other hand, the mass should be on y-aixs.

We did the graphing with MS Excel. It was easy to make a graph and we can get the ideas easily.

Steps
- Open the MS Excel program and complete the table
- Click 'Insert', select 'scatter', then the graph will come out.
- Click anyone of the points and choose "Add Trendline" -> "Linear" or "Polinomial"
- Display Equation on the Chart
- Make it pretty!


And here are three graphs that we did in the class.

This is a video that demonstrates how to make a graph on excel.

http://www.youtube.com/watch?v=8B8kFVNzlQ8

Mole ----- By Sally Chen

Masses
Relative Mass:  expressed by comparing it mathematically to the mass of another object.
     - Hydrogen was used first as the standard; now Carbon is the standard (assigned to be 12).
Atomic Mass:  of 1 atom of the element
Formula Mass:  of all atoms in an ionic compound
Molecular Mass:  of all atoms in a covalent compound
Molar Mass:  mass of each mole of each element (in g/mol); formula/molecular mass of any pure substance.

WARNING:The following video contains an extremely annoying yet catching tune.
If you are allergic to such things, or do not wish to have a song stuck in your head, leave now.  :D

The Genius Avogadro:
Avogadro's Hypothesis:  equal volumes of different gases at the same temperature and pressure have the same number of particles.
Avogadro's Number:  6.022 x 10 to the 23rd (particles per mole)

Lab 2E -- By Nemo Jin

Determining Aluminum Foil Thickness

Formulas you might use

--V=L*W*H

   volume = length * width * height

--D=m/V

   density = mass / Volume

--Unknowns 

   volume;height

--Knowns

    mass;width;length;density

--Formula we are using 

    volume = mass / density

    height = volume / (length*width)

 Aluminum Foil

--Al

--92%~99%

--silvery white metallic element

--Density: 2.70g/cm*3 

Objectives

--to understand the key point of precision and accuracy 

--to calculate the thickness(height) of the aluminum foil

--to use absolute uncertainty in expressing your answers

Supplies

--3 pieces of aluminum foil

--metric ruler

--centigram balance

Procedure

--label three aluminum sheets 1,2 and 3

--use a metric ruler to measure the dimension of each aluminum foil

--measure the mass of each aluminum foil

--express your answer in scientific notation with proper significant numbers and absolute uncertainty

        length (cm)              width (cm)            mass (g)       Thickness(cm)

   1        16.80 ± 0.01                           15.31±0.01                      1.01±0.01              1.45*10^-3

   

   2        17.01±0.01                             15.60±0.01                      1.08±0.01              1.51*10^-3

   3        17.41±0.01                             14.59±0.01                      1.02±0.01              1.49*10^-3

Density --- By Tina Zhao

Density:
-The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ

Formula: 
-Mathematically, density is defined as mass divided by volume,Volume us defined as Mass divided by Density,and Mass is defined as Density multiply Volume:

   V=M/ ρ , M= ρ v

Ex1. An iron bar has a mass of 1200g with a volime of 1.25L,what is its density?

         we can use formula:  ρ=1200g/1.25=9.60g/l

Ex2. Neon is contained in a glass bulb having a volume of 22.4L. If the density of the neon is 0.900g/L, what is the mass of neon in the bulb?
     we can use formula: M=density x Volume, 0.900x 22.4=20.2g

Ex3. What is the volume of a tank that can hold 18 754 Kg of methanol whose density is 0.788g/cm³?
      if they have different Units, we should change Units first, and then calculate!!
    1.0.788g/cm³  became 0.000788kg/cm^{3
     2. we use: V=Mass/Density, 18754/0.000788=2380000000}cm<sup>3

 If you want to try more Density problem,the website is http://www.sciencebugz.com/chemistry/chprbdens.htm</sup> 

             Density of water = 1.0g/mL
             Dobject > Dliquid =sink
             Dobject < Dliquid =float

Measurement --- by Ria Park

Measurement
- Every measurements are the best estimate.
- The exact numbers are when we can COUNT

Absolute Uncertainty
- The uncertainty forms in the unit ofmeasurement, not in a ratio.
- There are two method : 1. - Make at least 3 measurement
                                           - Calculate the average
                                           - The absolute uncertainty is the larrgest difference between the average and the
                                              the lowest or highest measurement.

E.g. Trial #                 Mass of an object
           1                             23.56cm
           2                             23.57cm
           3                             23.34cm    <----- it should be removed.
           4                             23.54cm

 }Average is = (23.56 + 23.57 + 23.34 + 23.54) / 4 = 23.50=
 }Difference between the average and the lowest measurement = 23.54 - 23.50 = 0.04
 }Difference between the average and the highest measurement = 23.57 - 23.50 = 0.07
 }So the mass would be 23.50 ± 0.07cm


- Method 2. - Determine the uncertainty of each intrument
       +) Measure to the best precision as possible when making a measurement. So you should estimate to a fraction 0.1of the smallest segment on the intrument.

E.g. Ruler = 0.1   0.01   0.01
       Themometer = 1℃   0.1℃  0.1℃e
       100㎖ graduated cycilnder = 1㎖   0.1㎖   0.1㎖
       400㎖ beaker = 50㎖   5㎖   5㎖


Relative Uncertain and Sig. Fig.

Relative uncertainty = Absolute Uncertainty / Estimated measurement

- It cane be a) in percent form(%)
                   b) using sig.fig.
- The numebr of sig fig indicates the relative uncertainty : The largest digit in a measurement in uncertain as it could be one digit higher or one digit lower very easily.
- Sig figs are ALL of the certain digits plus ONE uncertain digit in a measurement.

Significant Figures --- By Sally Chen

Significant Figures
1. A bunch of certain digits and only one uncertain digit (at the end)


Exact Numbers
1. A certain amount
2. No rounding is required
3. Has infinite number of sig figs (eg. 1 pen = 1.000.....00 pen)


Significant Figures Rules
1. Non-zero digits are always significant 
2. Zeroes between two non-zero numbers are significant 
3. Zeroes at the beginning of a number are never significant 
4. Zeroes that fall at the end of a number and after decimal point are always significant
5. Zeroes at the end are AMBIGUOUS. They are not considered significant, unless there is a decimal that follows it.


Practise: 
How many sig. figs in the following numbers?
a. 500.0
b. 500
c. 0.05
d. 5.00x10^3


Adding / Subtracting with Significant Numbers
1. Perform the operation as usual 
2. Round to the smallest of digits past the decimal in any terms.

Multiplying / Dividing with Significant Numbers
1.Perform the operation as usual 
2.Round to the smallest number of significant digits in any operand.

Rounding when it comes to 5

Look at the digit after the position of rounding:

{IF}  > 5,  {THEN} round up!
{IF}  < 5, {THEN} keep the same!
{IF}  = 5 with digits after 5, {THEN} round up!
{IF}  = 5 without digits after 5,  {THEN} round to the nearest even number!

DO NOT ROUND UNTIL THE FINAL ANSWER!!

Acid and Naming Acid --- By Nemo Jin

What are acids
--Chemical compounds that form solution containing hydrogen ions (H+).
--Hydrochloric acid is a strong acid.
--CH3COOH(vinegar) is a weak acid.

"aq"

--Refers to aqueous or "dissolved in water".

--Acid compounds usually only take one properties of acids when dissolved in water.

Naming Acid compounds
1.Naming acid compounds "--ate".
   All acids with oxygen and suffix "--ate".
   --Drop "hydrogen".
   --Drop suffix "-ate".
   --Add suffix "--ic acid" .
  EX. Hydrogen Carbonate ---- Carbonic acid


2.Naming Acids compounds "--ite"
   --Drop "Hydrogen".
   --Drop suffix "--ite".
   --Add suffix "-ous acid"..


3.Naming Acids compounds lacking oxygen
   --Drop hydrogen.
   --Add prefix "Hydro-".
   --Drop suffix "-ide".
   --Add suffix "-ic acid".

Weak versus Strong

--Strong acids, such as HCl dissociates completely into H+ and Cl+ ions.

--Weak acids, such as CH3COOH dissociates incompletely into H+ and CH3COO ions.

Law of Definite Composition (Proust's Law)
   --Chemical compound always has the same proportion of elements by mass.


Law of Multiple Proportion (Dalton's Law)
   --Same elements can combine in more than one proportion to form an compound.




Naming Acid Link