Formula of a Hydrate

    So today we did a lab about calculating the hydrate. One common example of the hydrate is called calcium chloride. Another common hydrate is called the carbohydrate. So here is one hydrate which is anhydrous, aka Cobalt (II) chloride.



And after i did some research in the internet, I found out there is this another form of Cobalt (II) chloride which is called Cobalt (II) chloride hexahydrate. Which looks like this

So after doing this lab I think I am much prepared for the quiz which will be next wednesday. 

Calculate The Empirical Formula Of Organic Compound~

An organic compound : any substance that contain CARBON

When we do the calculation, we can write a balanced chemical equation for the burning of CxHy
(CxHy + zO2 -----> xCO2 + y/2H2O)

1. We should calculate the moles of CO2 and H2O produced
2. Find the mole of C and H in the CO2 and H2O
3. Find the ratio of C : H
4. Multiply the ratios to get a whole number

For example...
1.  What is the empirical formula of a compound that burns to produce 8.45g of CO2 and 1.73g of H2O?
mol of CO2 = 8.45/44 = 0.19        mol of C in CO2 = 0.19C
mol of H2O = 1.73/18 = 0.10       mol of H in H2O = 0.2H
Mole ratio = 1:1
Therefore,the empirical formula is CH

2. When 6.28g of an organic compound is burned,10.22g of CO2 and 5.18g of H2O is produced?What is the empirical formula?
mole of CO2 = 10.22/44 = 0.232   mol of C in CO2 = 0.232C
mole of H2O = 5.18/18 = 0.288     mol of H in H2O = 0.576H
Check Mass :
0.232C x 10.22g = 2.371g
0.576H x 5.18g = 2.98g
6.28g - 2.371g - 2.98g = 0.929g ----->   Oxygen
0.929/16 = 0.058mol Oxygen
Mole ratio = 0.232 : 0.576 : 0.058
                  = 4        : 10      : 1
Therefore,the empirical formula is C4H10O

Empirical formulas and Molecular formulas

Empirical formula: it gives the lowest term ratio of atoms (or moles) in the formula. *All ionic compounds are empirical formulas*

Ex: C3H6 (propene) ---> molecular formula
     CH2 ----> empirical formula


Molecular formula: it is a multiple of the empirical formula and shows the actual number of atoms that combine to form a molecule

Ex. A molecule has an empirical formula of C4H10 and a molar mass of 29 g/mol, what is the molecular formula
Ans: C2H5

More Mole Conversion(2)

Today we are going to teach you to solve Two Step Mole Calculartion Problems~

If we were asked to convert 22 grams of copper to atoms of copper, we'd have to go from one end of the map to the other. Instead of doing a simple one step calculation, we'd need to do a two-step calculation, with the first step going from grams to moles and the second step going from moles to atoms.

How can we solve this kind of problem? Well, we start off by doing the same thing that we did in our last example: We had to convert grams to moles before, and we can see from the map that we have to convert grams to moles now, too. To refresh your memory, here's the calculation from last time:

In the next step, we do the same thing over again, except that we need to add another T to the T-chart. When you do this, take the units of the thing at the new top left and put them on the bottom right (in this case, moles). Then take the units of what you want (in this case, atoms) and put it in the top right. Finally, put in your conversion factors, which from the chart above is Avogadro's number, or 6.02E23. Since this number refers to the number of atoms in a mole of a substance, we put this in front of "atoms of copper". Again, put the number "1" in front of moles, because we're saying that there are 6.02E23 atoms in ONE mole of an element.
When we add all these terms in, we can cross out the units that cancel out, as shown. To get the answer, multiply all the numbers on the top together and divide by the numbers on the bottom. Your answer should then be set up like this:

And that's how you do mole problems!

More Mole Conversions

   So today we did more mole conversions, it involves more than one step, for example,

What is the mass of 2.78 X 10 ^22 Fe atoms:  2.78 X 10^22 / 6.022 X 10^23 X 55.8 = 2.58 g

Moles

So last class we learned about moles, and more masses. We also learned about Avogadro's hypothesis, he said if there're equal volume of different gases at the same temperature and pressure have the same number of particles. We also learned about different masses, formula mass, molecular mass and molar mass.

The last thing we learned about is Avogadro's number, the number of particles in 1 mole of any amount of substance.

6.022 x 10 ^23 particles/mole


I also found this interesting song about mole----http://www.youtube.com/watch?v=8vaaRPBXHgM

Graphing

It's always easy to graph a picture by using computer, so that we can use Excel to record all the data and graph those data immediately and correctly.

1)First of all, we have to set up two different objects that we want to graph, one for X-intercept and the other for Y-intercept
2)Record the data you have
3)Select all the data and click SCATTER from chosing the graphing style
4)Decorate your table! (try as much change as you can :)

LAB 2E

So by doing today's lab we got deeper into mass, volume and density. We did the lab by using aluminum foils, find out their density and measurements and we also did some questions that are related to the measurements.
So this link below can explain more about density

http://www.youtube.com/watch?v=Q4EBOE4pJyw

Accuracy & Precision

Accuracy : how close the measurement comes to the accepted/real value

Precision : how reproducible a measurement is compared to similar measurements

No measurement is exact. Its just a estimation. It may still has some degree of uncertainty

~Absolute uncertainty = largest difference between the average and the lowest/highest measurement

Method 1 : Calculate the average(at least 3)

For example : 8.3, 8.5 & 8.1

Average = 8.3
Absolute uncertainty = 8.5 - 8.3 = 0.2
It will recorded as 8.3+/-  0.2

Method 2 : Determine the uncertainty

Measure the best precision that you can. You should estimate to a fraction 0.1 of the smallest segment on the instrument scale.

For example :
Thermometer  Smallest : 1degree,   Best precision : 0.1degree,   uncertainty+/- : 0.1degree

~Relative Uncertainty = Absolute uncertainty/Estimated measurement

                                    

SIGNIFICANT FIGURES

So last class we learned about sig figs, the last digit is always uncertain, there're 3 rules in sig figs, they're: leading zeros aren't counted (0.01); trailing zeros after the decimal point are counted (10.050); trailing zeros without a decimal point ARE NOT counted (12000). we also learned about exact numbers, some quantities, they have certain amount with no rounding and they have definite sig figs.

We also have different rules for rounding (1. look at digit after position of rounding; 2. >5, round up; 3. <5, same value; 4. =5, if more non zero digits after 5, round up; =5, ends with 5, round it "even")

GOLDEN RULE: (aka differences between adding and subtracting with multiplying and dividing)

1. Adding and subtrating------------> round to fewest number of DECIMAL PLACES.
2. Multiplying and dividing----------> round to fewest number of SIG FIGS.




After studying about the sig figs, I found it not that difficult because I have done some of that in my physics class. Maybe that is why I have some basics with this material.

SEPARATING MIXTURES~

Why we separate?
Because we want to find what different components and properties do the mixtures have.

We base on these strategy to find :
high/low density                reactive/inreactive
volatile/non volatile           magnetic/non magnetic
slouble/insoluble               pol;ar/non polar

Also, the teachniques are also very important.
We have.......
1. Hand separation & Evaporation
~by hands....by a magnet or sieve....by boiling away the liquid to get solid remains
2. Filtration
~by using filter paper to filter the solid particles in order to get the filtrate
3. Crystallizatiuon
~by evaporating/cooling so that the solid comes out as pure crystal
4.Gravity separation
~by using a centrifage that can force the denser materials to the bottom of the test tube
5.Solvent extraction
~by using liquid/separatory funnel in order to remove the unwanted material.
6.Distillation (liquid in liquid solution)
~by heating a mixture....the liquid with the lowest b.p. boils first...the vapour ascents to distillation flask and enters condenser, finally the gas cools and condenses back to liquid dropping the distillate as a purified liquid
7.Chromotography
a. paper chromotography
~by using a sheet or strip....components appear as separating spots spread out on the paper after dying or 'developing'
b. Thin layer chromotography
~by using a thin layer of absorbet(Al2O3 / SiO2)....components appear as spots on the sheet.

Oct 19, Lab 3B

lab 3B: Separation of a Mixture by Paper Chromatography
we use 3 color dyes (unknown, green and either red, blue, and yellow).
-And drop those color on each piece of chromatography paper
-Put the paper into the teststube, which have already contained a small amount of water
-Wait for 20mins

Then the result may seem like the picture from below

Conclusion: Chromatography is one of the seperation that can seperate complex mixture, such as food colour from above. They are both combined with different colour and get the new one, and originally each color have different solubility, through the chromatography paper, different will stop according to their component's solubility.

ACIDS

    So today we learned about naming acids, acids are formed when a compound composed of HYDROGEN ions and a negatively charged ion are dissolved in water { Aqueous (aq) }. We also learned about the guidelines, like use "hydro" as the beginning; last syllable of the non metal is dropped and replaced with "-ic"; add "acid" at the end, so its basically like ____ide -----> hydro____ acid

We also learned about naming complex acids, its like we replace -ate with -ic, and -ite with -ous.

Ex. HC1(aq) + H20(l) -----> H30 (aq) + C1(aq)

Writing + Naming Ionic and Covalent Compounds

Ionic Compounds-Composed of 2 or more particles(oppsitely charged), which is Metal and NON- Metal
Ex.
K+1  ,   N3-   >   K3N , as three more Potassium get 3 positive charge to held with Nitrogen 3- and get the balance- 0.

Copper (I) Oxide > Cu2O 
Copper has two different charge as we see in the periodic table, that's why we have to notice that which charge do we use it.   If it's +2, we use Roman number notice it by (II).

Covalent Compound
-Share electrons
-Compose with NON- Metal and NON- Metal

Diatomic molecules: H2, O2, F2, Br2, N2, Cl2, I2
-Use GREEK prefixes to Indicade the number of atoms.

mono-1  di-2  tri-3  tetra-4 penta-5 hexa-6 hepta-7 octa-8 nona-9 deca-10

Ex.
N2O4 >  dinitrogen tetroxide

Heating And Cooling~

THE HEATING PROCESS ~

1. Put on your safety equipment.

2. One partner will as observer, the other will act as recorder. Recorder is responsible for stating the 3os intervals when temp. readings are to be taken. Prepare the table for experimental result.

3. Obtain a test tube assembly consisting of a thermometer endedded in solid dodecanotic acid and remove the cotton plug and save it for the end of experiment.

4. Put 300mL of tap water in a 400mL beaker and place the beaker on a hot plate. Turn it on to high heat and raise the temp. of water bath between 55 and 60. Monitor the water temp. with thermometer. While the water is heating, set up a ring stand withg a buret clamp to hold the test tube.

5. When the water bath reached 55, turn the hot plate to low heat. Lower the test tube into the water line. Record the temp. of dodecanoic acid and every 30s after that. During the heating process, the temp. of water bath should be monitored with its thermometer to make certain that the water temp. remains above 55.

6. Continue temp. recording until the temp. above 50. As the dodecanoic melts, stir it gently to mix the solid and liquid. Record the times when melting begins and ends, as well as observations.

7. Turn off the hot plate.

THE COOLING PROCESS~

1. Require teamwork, table 1 will be continued to read.

2. Raise the test tube out of the hot water bath and clamp it in position in room temp.. Just replace the hot water in beaker with room temp.

3. Immediately start monitoring the cooling process. Record the temp. of liquid dodecanoic acid

4. Record the temp. of dodecanoic acid every 30s until the temp. is near 25. Record when solidification begins and ends , as well as observations.

5. When the temp. at or near 25, stop recording temp. readings.

6. Reset the test tube with cotton plug. Return the test tube to your instructor and put away all your equipment.
7. Wash your hand with soap and water.

The Heating/Cooling Curve of a Pure Substance

    So basically what we did today is the heating and cooling curve of a pure substance, we also needed to do a flow chart because we might have a lab next class.

   So A is a solid state at any temperature below melting point; A-B turns heat energy to kinetic energy; B is the point where it starts to melt or be frozen; B-C exists in both solid and liquid state and the temperature remains constant, it is also the melting point; C is completed melted and it transformed from solid to liquid; C-D is a liquid state and it gains more energy while heated, besides, the temperatures continues to increase; D is still in liquid state, the molecules received enough energy to overcome force of attraction between particles in the liquid, and the liquid begins to turn to gas; D-E exists in both liquid and gaseous states while the temperature remains unchanged, heat energy is also absorbed to overcome intermolecular forces, it is also the boiling point; while we reached E, all liquid turned to gases; Last but not least, E-F, gas particle keep absorbing to move faster.

 

 After reading the textbook from pages 25-34, I discovered something interesting. Most useful ideas are simple in theory, but complicated in practice. I also learned a lot of stuff about what a chemist is specialized, the use of water, what is a mixture, solution, and what is distillation, I have learned about that but after studying this it recalled my memory about this. I also read about a complicated process called electrolysis.

Matter is Made of AtomsAs we know that, matter is everything around us. We can made observations by viewing, such as smelling or feeling are called macroscopic observation to recongnize different matter. Also, by mesuring the melting point, boiling point, heat of fusion, temperature and mass are called macroscopic properties. And we can use microscopic model to explain the behavior of matter in a micro (small) unit.

Atom means this smallest possible piece of something. Elements are pure substances that cannot be broken down, and it presumes that every element contains only one type of atom. Molecules are the particles that made of more than one atom. Compounds are made by combining elements in definite proportions

Lab 2C : Chemical and Physical change

What we are doing today is shown from below step:

1)Wear safety goggles and lab apron
2)Otain 1/3 solution in each four test tubes
3)Place a clean medicine dropper in each test tubes and set it in the test tube rack
4)Draw a grid as it shown in the lab book (P.19) on our note
5)There will have six different combination on each cell of grid
6)Record and make comments in your tube
7)Clean up
8)Wash your hands thoroughly with soap and water

Chemical change:
-New substances are prodused
-irreversible . Ex. burning anything, cooking

Physical change:
-No new substance is formed
-chemical composition does not change
-reversible Ex. Melting point, boiling point

Through these conditions from above between Chemical and Physical change, we can determind what kind of change does the matter is happening by those conditions.

~mATTER~

WHAT IS MATTER?????

Matter is the Stuff Around You

Matter is everything around you. Matter is anything made of atoms and molecules. Matter is anything that has a mass.

                                 Matter can be divided into :

   Pure substance                        &                       Mixture

    

       can be divided into :                            can be divided into :

Element   &    Compound                    Homogeneous  &    Hetergeneous                             

                                                                                                  

(Element is made of atoms)                           (Homogeneous uniform throughout)

(Compound is made of elements)                  (Hetergeneous isnt uniform)

Element can be divided into :                  

Metal, metaloid and non-metal

Compound can be divided into :

Ionic and covalent

Elements and compounds can move from one physical state to another and not change = physical change

For example : Oxygen (O₂) as a gas still has the same properties as liquid oxygen. The liquid state is colder and denser but the molecules are still the same.

If the formula of water were to change, that would be a chemical change = chemical change

For example : If you added another oxygen atom, you would make hydrogen peroxide (H₂O₂). Its molecules would not be water anymore.

More properties of matter :

Matter is commonly said to have 3 states

1. SOLID------rigid

 Don't change shape easily experiences small changes in volume when heated.

2. LIQUID

Takes the shape of the container and experiences slight changes in volume when heated.

          

 3 . GAS

Takes the shape of the container and experiences dratic

 in volume when heated

Class 2

So basically this class we learnt about the unit conversion chart and some unitary rates, We thought this class was kind of annoying because at first because its actually pretty confusing while you got to memorize all these units while we already needed to prepare a quiz for this. But thats kind of what we did in this class.

Chemistry 11 note: Scientific Notation Sept 21, 2010

Scientific Notation- is used to express very large or very small number using powers of 10
Ex1

Express in scientific form:
a) 25 000 000 000

Ex2Express in standard form ( basicly it's the opposite way)

Generally, when the power of 10 is positive, the point will move to the right side; otherwise(which is negitive) it moves to the left side.