Empirical Formula of Organic Compounds By Sally Chen

- An organic compound is a covalent compound containing carbon.
- Process:
     -find CO2 and H2O (mole)
     -find C and H
     -C:H
     -CxHx
     -check the answer
     -if the totals don't balance, there is another element in the compound (usually O or N)
              -difference of totals = mass of the other element
     -CxHx or CxHxUx
- Example
     An organic compound weighed 99.99 g was burnt and in the product there is 191.29 g carbon dioxide and 117.36 g water.  (there IS the element O in the compound)
           - CO2:  191.29 g x 1 mol / 44.0 g = 4.3475 mol
             H2O:  117.36 g x 1 mol / 18.0 g = 6.52 mol
           - C:  4.3475 mol
             H:  13.04 mol
           - C:H = 1:2.999424957 = 1:3
           - Check:  C:  4.3475 mol x 12.0 g / 1 mol = 52.17 g
                       H:  13.04 mol x 1.0 g / 1 mol = 13.04 g
                       52.17 g + 13.04 g = 65.21 g < 99.99 g
           - O:  99.99 g - 65.21 g = 34.78 g
             34.78 g x 1 mol / 16.0 g = 2.17375 mol
           - C:H:O = 1:2.999424957:2.17375 = 1:3:2.17375 = 2:6:1
           - C2H6O

Chapter 4 Empirical & Molecular Formula & Percentage Composition -- By Nemo Jin

Chapter 4 

--Empirical & Molecular Formula & Percentage Composition

Percentage Composition

Definition:

--Percentage Composition is the percentage of the mass of a certain element in a compound 

Calculation:

--Calculate the molar mass of the compound

--Calculate the mass of each element in the compound

--The %composition of X element = mass of X element / total mass of the compound * 100%

Ex.

In ionic compound FeO

The percentage composition of Fe = (55.8 / 55.8 + 16.0)*100% = 77.7%

Applied skills:

(Connect Empirical Formula with Percentage Composition)

--Use percentage composition to find out the empirical formula of a certain compound.

Question: 

A compound is made of 72.8% Oxygen and 27.2% Carbon. Find out the empirical formula of that compound.

--Assume there is 100g compound 

--so that the mass of oxygen is 72.8g and the mass of carbon is 27.2g

--find out how many moles by doing “72.8g/16.0g=4.55 moles” and “27.2g/12.0g=2.27 moles” 

--the biggest number is divided by the smallest “4.55/2.27=2”

--write out the empirical formula, gives you the formula of Carbon Dioxide CO2


Empirical Formula And Molecular Formula 


--Empirical Formula of a compound gives you the lowest-term of ration of atoms in the formula, for example C2H3. 2 and 3 are both not divisible by any number that is larger than 1.


--Molecular Formula of a compound gives you all atoms exist in that compound. For example C4H6. 4 and 6 are both divisible by 2.


Conversion.
--Convert empirical formula to molecular formula you just need to multiply every atoms by n
--Convert molecular formula to empirical formula you just need to divide every number by the same number n.

Mole Conversions --- By Tina Zhao

Mole Conversions

One- Step mole conversions

Conversions Particle/Atom/Formula Unit into Mole

Ex.1:How many moles of Carbon atoms are there in 3.01 X10^24C atoms?

             3.01 X 10^24   atoms 1 mol C/ 6.022ｘ10²³

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

Separation Techniques -- by Tina Zhao

*Basis for separation:different components,different properties
*strategy:devise a process that discriminates between components with different properties.
e.x:high density/low density

separation
-components in a mixture retain their identities
-the more similar the properies, the more difficule it is to separate them.
some Basic Techiques
1.Filtration:(solid and liquid) can remove suspended material from water as long as the pores in the filter paper are smaller than the particles of the suspended substance.
2.Floation:
3.crystallization and Extraction:(solid in liquid)
  -precipitation
  -solid are them separated by filtration or floating
  -saturated solution of a desired solid.
4.Distillation:(liquid in liquid solution)
  -lteating a mixture can cause low-boiling components to volatilize
  -then collect and condense the volatilized components
5.chromatography:is a method for analyzing complex mixtures (such as ink) by separating them into the chemicals from which they are made. Chromatography is used to separate and identify all sorts of substances in police work. Drugs from narcotics to aspirin can be identified in urine and blood samples, often with the aid of chromatography.
.http://www.yesmag.ca/projects/paper_chroma.html see more information about chromatography.
6.solven extraction:
  -mechanical mixture
  -use liquid to dissolve one solid but not the other so the desired solid is left behind or dissolved
7.Gravity Separation:
  -A centrifuge whirls the test tube around at high speeds forcing the denser materials to the bottom.
Hand Separation
-hand separation(soild and solid)
-A mechanical mixture or heterogeneous mixture can be separated by using a magnet or sieve
Evaporation
-Boil away the liquid and the solid remain

The Only Thing Constant in Life is Change -- by Ria Park

Marcroscopic

- physical objects that are measurable and can be seen just by eyes


Physical Change
- a solid is formed
- heat is produced(e.g. if we band a copper string, the part that is banded is getting hotter.)
- a liquid is fromed
- change in shape

Chemical Change
- change in colour
- a gas is formed
- change in odor
- a solid is formed
- heat is produced
- a liquid is formed
- light is produced


These are the macroscopic behaviors that we could observe from today's lab.


This is the table that we did.

Change You Can Believe In --- By Nemo Jin, Sally Chen

Physical Change

Description:

---Physical changes occurs when the state of matter changes, or two substance physically combine together.

---No new substance is being produced.

Three states of matter:

Solid: 

        --Particles are packed together tightly. They can only vibrate within a certain area.

Liquid:

        --Particles can move around. The shape of a liquid is determined by its container. The volume of a liquid depends on temperature and pressure.

Gas:

        --Particles are able to move around freely at a high speed. They are separated with no regular shape.

Chemical Change

Description

-- New substances are being produced.

-- Changes in composition of a substance.

-- Color changes; odor changes;energy is released (light, heat)

-- Atoms are rearranged in chemical changes.

                                                          

Chemical Changes

Synthesis; is when simpler reactants combine together to make a compound. Ex; the picture below, showing that the N2 and 2O2 combine together to make 2NO2.

Combustion; is when only the atom arrangement changes. Ex; picture below only shows that the arrangement of the atoms changes. They didn’t break down or anything.

Decomposition; is when a reactant breaks into simpler reactants. Ex; picture at below, the 2H2O breaks into 2H2O + O2.  

Pictures provided by Fadhila Science-Stuff

Scientific Notation and Matter--Chemistry 11 by Tina Zhao

Scientific Notation:
-Scientists have developed a shorter method to express very large numbers. This method is called scientific notation. Any number in scientific notation will be between 1 to 10 and multiplied by a power of 10.

E.g. write  123,000,000,000 in scientific notation

First step: Put the decimal after the first digit and drop the zeros

Second step: you look the coefficient first.In this number coefficien will be 1.23.

Third step:count the number of places from the decimal to the end of the number.and then found exponent 

Answer:

*Numbers less smaller than 1 will have a negative exponent.

*Move decimal to the left-positive exponent

                                 rigth-negative exponent.

Rules for Multiplication in Scientific Notation:
1) Multiply the coefficients
2) Add the exponents (base 10 remains)
Example 1: (3 x 10⁴)(2x 10⁵) = 6 x 10⁹
Link for Scientific Notation practice :http://www.edinformatics.com/math_science/scinot_mult_div.htm
Rules for Division in Scientific Notation:
1) Divide the coefficients
2) Subtract the exponents (base 10 remains)
Example 1: (6 x 10⁶) / (2 x 10³) = 3 x 10³
Link for Science Notation practice:http://www.edinformatics.com/math_science/scinot_mult_divb.htm

what is Matter?
-Anything that has Mass and Takes up space.
What is Mass?
-A property of matter that cause it to have weight. Mass measures the resitance of an object to a change in its state of motion.

Matter

1.  Mixture                                                      

-have more than one set of properties                     

-physically combined                                         
-more than one kind of substance                             

 Homogenou:i)uniform throughout.ii)appear to have only one component.*solution,colloid                
Heterogeneous:i)non uniform.ii)appear to have more than one component.*suspension,mechanical mixture.                  

2. pure substance
-one set of properties
-one kind of particle
Element:i)simplest form of matter.ii)can't be decomposed.iii)made up pf atoms.*metal,non-metal,metalloids
Compound:i)made up of element.ii)smallest particle is called molecule.
*Ionic:acid,base salt
*covalent:organic compound

Derived Quantity Conversion -- Chemistry 11 by Ria Park

Meaning

A derived quantity is when there is more than one SI unit in a single quantiy

e.g. Convert 50 ㎞/h into m/min

                                          First. ㎞ -> m

                                                  use 1km = 1000m

                                      Second. h -> min

                                                  use 1h = 60min

So the calculation would be like this :

          50㎞/h X 1000m/1㎞ X 60min/1h = 3000000 m/min


More examples :

              1) Convert 1mg/dL into g/L

                 1mg/dL X 1g/1000000 X 1km/100m = 1 X 10^-7 g/L


             2) Convert 1㎝/㎲ into ㎞/s

                  1㎝/㎲ × 10^6㎲/1s × 1m/10^2㎝ × 1㎞/10^3m = 10㎞/s


              3) Convert 36.4㎣ into ㎥

                   36.4㎣ × 1m/10^3㎜ ×  1m/10^3㎜ × 1m/10^3㎜
                           = 36.4㎣ × 1㎥/10^9㎣
                           = 3.64 × 10^-8㎥





           

Quantities and Unit Conversions--Chemistry 11 By Sally Chen

Quantities
-All measurements in Science come in 2 parts: the number + the unit.  These number and unit combinations are called quantities.

-Basic units: 
Length                                    Metre                                  m
Time                                       Second                                 s
Mass                                     Kilogram                               kg
Amount of Substance              Mole                                     mol
Luminous Intensity                 Candela                                  cd
Temperature                           Kelvin                                    K
Electric Current                      Ampere                                   A

Unit System
SI system:
  --A French system dating back to the early 1800's using prefixes and symbols.
  --metre-second-kilogram
Imperial System:
  --feet-second-pound

SI Prefixes and Conversions Factors

Link:

How to Convert Units of Measurement

Lab safety summary -- Chemistry 11 By Nemo Jin

Lab safety summary -- Chem 11

Do's

--Listen carefully to all instructions that your teacher gives you.

--Read through the whole activity instruction before you start.

--Know where to find all safety equipment.

--Know all of the safety symbols (Go to part 4)

--Report to your teacher if any part of your body comes in contact with a dangerous substance or unknown  substance.

--Wear lab coats and safety goggles when you are doing experiments.

--Wear shoes that can protect your whole feet.

--Tie you hair back before you start.

--Clean and dry equipment and then put it away.

--Always wash your hands before you start and after you finish.

Don'ts

--Don't taste any substances!!!

--Don't smell any substances!!!

--Don't run in your classroom.

--Don't eat or drink in your classroom.

--Don't use broken glassware.

--Don't hold the containers close to your face.

--Don't touch any chemical substance.

--Don't listen to music.

--Don't start without your teacher's permission.

Safety Equipment

1. Fire extinguisher

2. Fire blanket

3. Eyewash 

4. Emergency shower

5. Acid-base neutralize solution

6. Safety goggles

7. Fume hoods

8. Lab Coats

WHMIS

The Workplace Hazardous Materials Information System has eight safety symbols to warn you about dangerous materials. 

Welcome to Chemistry 11!

Welcome to Chemistry 11!
Now, you can view all of your homework, assignments, test dates from this blog!