MaVa=MbVb

Today we went over pages 9 and 10. Finish page 5 for homework along with the bottom of page 4.

Remember, Molarity and Concentration are the same thing. The formula is Moles of Solute/Liters of Solution.

We also took notes about a pH Scale.

It is a scale that determines how acidic or basic a solution is.

It ranges from 0 to 14.

Below 7- Acid

7- Neutral

Above 7- Base

We can use mathematical expressions that have been determined experimentally to solve for concentrations, plt, and pOH.

1. pH= -log [H+]

2. pOH= -log[OH-]

3. pH+pOH=14

4. [H+]=10^(-pH) <- this is how you find the molarity of the acid
5. [OH-]=10^(-pOH) <- this is how you find the molarity of the base

just use these formulas to help with the homework... that was basically all we talked about.

I would personally like to go over the reason why we keep circling OH and H in the problems. I get that it has a certain meaning, but I wasn't there that day so I am out of the loop. Thanks!

Ionic Solubility

Dear period 8,

Today in class we did the Ionic Solubility lab. You were to observe the reactions of two compounds that either formed a reaction or not. After recording the data on the first page of the lab, we were to do the following pages according to the first page.

Homework: Finish lab, and finish problem #'s 3,4,5 from the Reaction Solubility 1 notes packet.

Thank you for reading my post, have a nice day.

a.v.

Solutions

Yesterday in class we finished our Mixtures Lab. We took each of the four mixtures and completed the evaporation test and went on to the filtrate lab. To fill out the back sheet of the paper, we can use the notes we took in class on Wednesday. If you want to check if you got the correct results, they are on moodle.
We also learned about solubility and dissolving. We learned that there are two categories of solutions: the solutes and the solvents.

Solutes:
-What is being dissolved
-Usually smaller amount

Solvents:
-What deos the dissolving
-Usually the greater amount

Ionic Compounds: When they are dissolved in water they split into ions (dissociation)
Covalent Compounds: When they are dissolved in water they do not split

*When the compounds are dissolved in water you change the subscrips to (aq), which means in water*

The homework is to finish the Mixtures Lab.
[The notes Mrs. Mandarino gave us in class are on moodle, in the notes section.
If you missed ChemDay, the make up assignment can be found in the homework log section on moodle.]

Mixtures

Homogeneous


The particles are evenly distributed

Heterogeneous

The particles remain thoroughly mixed throughout the mixture while the liquid is being mixed, but later settle to the bottom.



examples:

anything with "shake before use"

salad dressing

orange juice with pulp

children's medicine

* these are all known as suspensions



suspensions

after the particles settle out, the tyndall effect may be seen in the top liquid portion





Homogenous Mixtures

Solutions

are too small to reflect light or settle out
No tyndall effect
Examples:
Coke
Kool aid
Lemonade

Colloid
Are big enough to reflect light but not big enough to settle out.
Tyndall effect is seen

Examples:
milk solution


Today Mrs. Mandarino gave us our test back and our revised grade print outs. We began the new unit taking notes on mixtures. We learned there are two types of mixtures:


Kendall K
Mixtures

Limiting Reactants

 Limiting Reactant Strategy

If a problem mentions amounts of more than one reactant, its probably a limiting reactant problem.

1. Go from each reactant to amount of product (grams of each reactant to grams of product)
2. The reactant that produces the lower amount of predicted product is the limiting reactant.  This amount of product is also the amount that can be produced.
3. The other reactant is your excess reactant.

For Example:

Fe + S  à  FeS

If I have 28g of Iron (56 g/mol) and 24g of Sulfur (32 g/mol), how much FeS can be made and what is the limiting reactant?

28 g Fe  x  1 mol Fe  x  1 mol FeS  x  87.92g FeS  =  44 g FeS

                 55.85 g Fe     1 mol Fe       1 mol FeS

24 g S  x  1 mol S  x  1 mol FeS  x  87.92g FeS  =  66 g FeS

                32.07 g S     1 mol S         1 mol FeS

Fe is the Limiting reactant because it runs out first and produces less FeS.

Into to stoich.

Today, pages 3,4,5 and 6 were stamped. We went over the answers, and they should be posted on moodle.
We were supposed to take the first stoich quiz today, but it has been moved to Monday.

We worked on pg 9, 10, 11, and 12 which were intros to stoich. Most of the pages were review from the particulate nature unit. We reviewed how to balance equations.

Remember- the same amount of each atoms had to be on both sides of the equation.

We also learned how to figure out how much of each atom you need to balance an equation.


Example: 4Fe + 3O2 -> 2Fe2O3

How many molecules of oxygen would you need to react with 380 atoms of iron?

To figure out the answer to this question, you start with what you know. You know you have 380 atoms of iron. According to the equation above, you know that for ever 3 molecules of O2 you have, their are 4Fe atoms. Therefore the equation should be like this:

380Fe x 3 molecules of O2 = 285 molecules of O2
4 molecules of Fe

This is simple stoichiometry. To use stoich, you much always start with a balanced chemical equation.

We also filled out pg 14, which is more of this simple stoich.

Pages 15 and 16 are for homework. They will be stamped on Monday.
Remember the quiz had been moved to Monday!

-Rima S.

Mole Problems

Today in chemistry we went over homework pages which was pages 1 & 2.

Then we worked on page 3 and completed the first 2 problems by converting atomic masses to calculate how many moles were present. Problems c,d and e were to be completed for homework along with page 4.Then we started the lab, 'Mole Stations Lab' where we went from station to station to convert masses to moles and moles to masses. Some converstions to remember are:
1 mole= 6.02 x 10²³ atoms or molecules.

To find the molecular mass you add the masses of all the compounds. That can be used later to find the number of moles of an element.
Danielle F.

Introduction to Moles

January 25, 2011

We began class by stamping our homework, the Mole Lab, and reviewing pages 7 and 8.
(Review)
- a compound is ionic if it contains a metal such as NaNO3, and is simply named sodium nitrate
- if the metal is a transition metal, the compound includes roman numerals, such as Fe3N2, which is named iron (II) nitride
- a compound is covalent if it contains two nonmetals such as PCl5, which includes a prefix, in this case, phosphorus pentachloride

- to calculate the molar mass of a compound, first write the compound's formula. Then take the number of atoms of the first element and multiply it by the element's atomic mass, found on the periodic table. Continue to do this with each element, and add up the masses of each element at the end. For example,
carbon dioxide --- CO2
(one carbon atom, 1 x 12.01 (the atomic mass of carbon)) + (2 x 16.00) = 44.01 g
44.01 g is the molar mass of carbon dioxide (for each mole of CO2 there is 44.01 g)

To calculate the number of moles of 50g of carbon dioxide, use the multiplication method that I can't remember the name of. It involves canceling out units of measurement by putting them diagonally across from eachother ------ x ------- (< like that)

SO...
begin the equation with 50 g of CO2.
50g x 1 mole/44.01 g --- grams cancel out, so you are left to divide 50 by 44.01, to get the answer 1.14 mol CO2

Pages 1 and 2 just went into more depth with the multiplication method with the name I can't remember.
Here's an example problem: What is the mass of 3.57 x 10^-4 mol of N2O5?
start off with what the problem gives you-
3.57 x 10 ^-4 mol N2O5 x 108.02* g/ 1 mol -- mol cancels out, leaving you to multiply 3.57 x 10^-4 by 108.0 to get .0386 g N2O5 (you might want to round that)

*you get 108.02 (the molar mass of N2O5) by (2 x 14.01) + (5 x 16.00)

Thats basically it. The homework was to finish pages 1 and 2.

Chain Reactions and Review

January 14, 2011

Dear Period 8,

On Friday we went over Chain Reactions and Nuclear Reactors.We also received the 1st semester review packet. Webassigns are extra credit and The Test is on Monday January 10, 2011.

Notes: The atomic # determines the type of element. Isotopes is the term used to describe an element written in this format. Uraniium has an unstable nucleus, so it is always found decaying. The atoms that it is found with are atoms it has transmuted into.

Link to Alpha, Beta, and Gamma review: http://gbs-moodle.glenbrook225.org/moodle/mod/resource/view.php?id=652

Chain Reactions:

Examples: Uranium-239

Mass: 239

Atomic Numbef: 92

Event 1-2-3-4-5-6-7
# of Reactions 1-2-4-8-16-32-64

Nuclear Reactors:

Control rods- absorb neutron to slow down a chain reaction

Fuel rods- contain 3% of U-235

Moderator- Slows down neutrons, so control rods can absorb them.

Fission- Splitting of atoms for energy

Fusion- Combining atoms to release energy ex. sunstars

The answers to the review guide: http://http://gbs-moodle.glenbrook225.org/moodle/mod/resource/view.php?id=666

Homework: Finish review guide, Webassigns extra credit, and study for Quest

Anson. V

Jan. 4 2011

Today Mandarino stamped pg. 3 for homework. the homework for today was pg. 9 and #3 on pg. 10. we learned about radioactive decay as well as aplpha and beta particles(also waves). we learned that isotopes are atoms with the same protons but different neutrons. we learned half-lives were the time period it takes for a substance undergoing decay to decrease by half.

December 14- Double Replacement Lab

Today in class we mainly reviewed our results from the double replacement lab that we did yesterday(Monday the 13th). The equations from the lab are as follows: If you still have any questions about balancing equations than you should either talk to Mrs. M or go to the TLC because we will be having our quest about Balancing equations this Thursday(December 16th).

Today we were also given back our partner quizzes, in which we were informed that we didn't do to well on, so tonight for homework we have to correct them. If you were absent or still haven't taken the partner quiz then you can get it straight off the moodle. The answer key to the quiz will be posted later.

DON'T FORGET: Our chemthink and webassign are both due at 11:59 tomorrow night.

Study for our upcoming quest!

Chandler F.

Scribe Post: Thursday, November 9, 2010

Hello,
Today in class, everybody present collected an Activity Series sheet, which basically showed which metals and nonmetals were more/ less active.  Next, we read the lovely scribe post from last night.  After that, Mrs. M made a quick announcement.  She told us that she would not be in class tomorrow, that page twenty is our homework, we have a partner quiz tomorrow, and to be ready for a quiz monday, a quest next thursday, and a CSI/ Winter Break party next friday.  She also told us that we will be reviewing as well as starting the next chapter on both tuesday, and wednesday.  Afrer that, Mrs. M stamped, and reviewed page eighteen (last nights homework).  Page eighteen was about balancing equations.  When balancing, equations, it is essential to make sure you balance the equation.  How do I do that? You must be asking yourself right now.  Well, when balancing an equation, you must make sure to see that all the elements in the reactants and products are equal, like a teeter-toter.  Lastly, we did page nineteen, which was about predicting products.  You do this by seeing what kind of a reaction it is, depending on wheter it is a synthesis, decomposition, single replacement, double replacement, or combustion. 

Thats all folks.

Reactant Types

Today in class, we went over the homework from last night. Then, we talked about reactant types. There are five different types of reactants:

Shown using variables:

1. Synthesis(combination)= A+B ->AB

2. Decomposition= AB ->A+B

3. Single Replacement= A+BC->B+AC

**A must be more reactive than the element it is replacing (In this case it is B).

4. Double Replacement= AB+CD->AD+BC

5. Combustion= C6H12+O->6CO2+6H2O

** Combustion works with hydrocarbons. It will ALWAYS produce CO2+H2O.

Shown using formulas:

1. Synthesis: 2Mg+O2->2MgO

2. Decomposition: 2H2O->2H2+O2

3. Single Replacement: Cu+2AgNO3->2Ag+Cu(NO3)2

** If the element is less reactive than the element it is replacing, there will be no reaction.

4. Double Replacement: Pb(NO3)2+K2S->PbS+2KNO3

5. Combustion: C4H10+6.5O2->4CO2+5H20

Homework tonight is page 18. Don't forget!

Polarity

Polarity is a theory in chemistry that tries to explain the unequal sharing or sharing of electrons. These types of sharing electrons define what type of bond a substance is. The bonds are either polar, meaning that the substance has an unequal sharing of electrons, like water, or if it is non-polar, meaning the substance has an almost uniform electric balance, like methane. Also, polarity can also affect the physical characteristics of a substance like melting point, boiling point, freezing point, etc.
The pull between the elements is considered electro negativity, and it is measured and justified by the formation of an electric dipole. What a dipole is is a separation of positive and negative charges into two poles. Furthermore, whichever element has more pull is deemed delta negative, represented by the greek symbol for delta, also with a negative sign. The one with the least pull is deemed delta positive.

Alec W.

The Valence-Shell Electron-Pair Repulsion (VSEPR) Model

At the start of class Mrs. Mandarino stamped the homework pages 18 &19.

Then we reviewed Molecular Geometry, and we started on Molecular Geometry lab.


Molecular geometry is the three dimensional arrangement of the atoms that constitute a molecule. It determines several properites of a substance.

The Valence-Shell Electron-Pair Repulsion (VSEPR) Model

There are basic shape types for molecules.


Linear: In a linear model, atoms are connected in a straight line. The bond angles are set at 180 degree.

Trigonal plannar: The trigonal planar shape are somewhat triangular and in one plane. The bond angles are set at 120 degree.

Tetrahedral: "Tetra" means 4. This is when there are four bonds all on one central atom, with NO extra unshared electron pairs. The bond angles between the electron bonds are set at 109.5 degree.

Trigonal Pyramidal: Pyramidal-shaped molecules have pyramid-like shapes. Requires three dimension in order to fully separate the electrons. The bond angles are set at 107 degree.

Bent: The final basic shape of a molecule is the non-linear shape, also known as bent or angular.


Trigonal Planar: 115 degree


Trigonal Pyramid: 105 degree

Electron Pairs on Central Atom

2/2/0 - Linear
3/3/0 -Trigonal Planar

3/2/1

4/4/0- Tetrahedral
4/3/1

4/2/2

Example:

PCl3

4/3/1 - Trigonal Pyramidal

xAFU3ts6tVM/TOM4KplfatI/AAAAAAAAAAM/lqChlwS3emM/s1600/pcl3f.gif">xAFU3ts6tVM/TOM4KplfatI/AAAAAAAAAAM/lqChlwS3emM/s320/pcl3f.gif">

HW: Tuesday, Nov.16,2010 = Molecular Geometry Lab (questions), Chemthink & Webassign

Quiz | Review | ions

At the start of class Mrs. Mandarino stamped the homework pg. 11.

Then we reviewed Lewis structure

Example:

H2O

2 x 2e- = 4e-

1 x 8e- = + 8e-

12e- Needed

Minus the total of Valence e- 8e- Total Valence e-

4e- Shared

--------.. ---------- -Has 2 single bonds with equal 4 valence e-
[ H - O - H ] -Has 4 Dots to fill in the ammount of valence
------- `` --------- e- needed.

Next we took the first quiz of our series of quizzes.

Then we went over Covalent ionic bonds.

example:

PO4(3-)

Step 1:

Count the # of atoms total. In the case its 5. 1 P + 4 O = 5.

Step 2:

Take the total # of atoms and times that by 8. This will equal the amount of Valence e- needed

5 x 8 = 40 Valence e- needed

Step 3:

Count the total number of Valence e- for both atoms.

P = 5 valence e- O4 = 24 valence e-

Step 4:

Add the valence e-. [P] 5 + [O4] 24 = 29.

Step 5:

In order to follow the octav rule you must add the 3- e- to the total number of valence e-

29 total Valence e- + 3- = 32 valence eletrons.

Step 6:

Substract the amount of valence e- needed from the amount of total e-

40 valence e- Needed - 32 Valence e- total = 8.

The total amount equals the amount of valence e- shared.

Your math should look something like this.

5 x 8 = 40 Needed

5 + 24 = 29 Total valence e-

29 + 3 = 32 Total valence e- with the 3-

40 - 32 = 8 Shared

The Lewis Structure should look something like this.

------ .. ------

| :O: | 3-

| .. | .. |

| : O - P - O : |

| .. | .. |

| :O: |

| .. |

------ ------|

Ryan G.

Lewis Structures

Today in Chem, Mrs. Mandarino got the party started by showing the class how to draw Lewis Structures. 

And here are some guidelines to drawing Lewis Structures!

Step One: Count the total number of valence electrons in the compound.

Dont forget! If you are finding the structure of an ion, remember to add electrons for a negative charge and subtract electrons for a positive charge.

Step Two: Predict the arrangement of the atoms in the molecule, drawing a line to represent a single bond between each pair of bonded atoms.

• The first atom listed in the formula is usually the central atom.
• Also, remember that Hydrogen can only be bonded to one other atom.

Step Three: Find the number of valence electrons left over after forming the single bond.

• Remember, each single bond you draw counts for two electrons.

Step Four: Place electrons around the outside atoms until each is surrounded by eight electrons. (The octect rule)

• Hydrogen does not follow the octect rule, it will only have two electrons, Boron does not follow the octect rule as well, it will only need 6 electrons.

Step Five: Place any left over electrons around the central atom.

Here's an example of how a Lewis Structure looks for CO2

Kamila W.

Naming Covalent Bonds

Monday, November 8, 2010

Naming Covalent Bonds

Today in class we began to learn how to point out, formulate, and name Covalent Compounds. Today we began class by starting working on our journals, by the end of class we had finished pages 2,3,4,5. Page 6 was our homework for tonight. Page 1 is extra credit.

How to name COVALENT Compounds:
** Write the name of the first element, add appropriate prefixes except for mono
** Write the name of the second element, drop the ending and add -ide.  Add prefiexes indicating the number of atoms.


In naming covalent compounds we use Greek prefixes:

1-mono

2-di

3-tri

4-tetra

5-penta

6-hexa

Then you add the name of the Element

**Exception- The First element for covalent compounds NEVER has a prefix!**

GOT THAT?!

-Patrick W.

Unit Review

Today we began class by stamping pg 14 and going over the answers.
The answers are as followed:

a) magnesium iodine
b) cobalt (II) sulfide
c) copper (I) sulfide
d) Calcium oxide
e) aluminum chloride
f) manganese (IV) oxide
g) Barium Fluoride
h) Sodium Sulfate
i) Iron (II) Carbonate
j) Calcium Phosphide
k) Manganese (IV)Oxide
l) Aluminum Sulfate
m) Mercury (II) Oxide

Rules to remember when naming ions
-write the cation (first part of name)first,then the anion.
-Make sure to drop the ending of the anion(second part of name) and add -ide. ex: Calcium chlorine turns into calcium chloride.
-When given a polyatomic ion look up the name
-When given a transition metal, determine the number of electrons lost and indicate the charge using roman numerals.

ex: FeCl3 (This means we have 1 Fe and 3 Cl)
Look up the charge of Cl, it's -1

Fe
Cl-1
Cl-1 = -3
Cl-1
Because there are 3 Cl's with a -1 charge, there is an overall -3 charge
Next you determine what charge you would need in order for the ion to be neutral.
In this example you need a +3 charge, so the new name becomes: Iron (III) Chloride

Next we reviewed the entire unit as a class, by filling in the Review & Topic outline pages 1 and 2.
Some of the material we reviewed included:
-Whether an element will gain or lose and election and the amount it will gain/lose.
-Completing an orbital diagram and the electron configuration
-How to write the formula of 2 given ions
-How to name the compounds when given the formula
-Naming polyatomic ions
-Naming transition metals in a formula

Homework
Study for the test tomorrow!
Webassigns due Thursday at 11:59pm

Periodic Properties Review

First in class we decided that we would take the chemistry lab test on Wednesday. Next we went over the Periodic Properties 2 worksheet (pages 12 and 13). On page twelve we went over the first five questions, they compared the first two columns of the periodic table (Alkali Metals and Alkaline Earth Metals). Remember: columns are the rows moving from top to bottom, they are sometimes also called groups. Mrs. Mandarino also noted that we must know what the term valence e- means; which is the outermost e-. (This word will be used on the test tomorrow).

Then we went over page thirteen; we firsts discussed electronegativity. Electronegativity is an atom's ability to attract a shared e-. Once a bond of valence electrons is made, both atoms will share the electrons in a shared e-.

Factors that will affect electronegativity:

• Amount of energy levels (atomic size); Less energy levels=valence electrons will be closer to nucleus=smaller atom will "hog" shared e- more.
• Shielding electrons; more shielding electrons=weaker pull from nucleus=atom will not "hog" shared e-.
• Number of protons in nucleus of atoms that are in the same period; greater pull from nucleus=smaller atom will "hog" shared e- more.

When going down-electronegativity will decrease.

Why?

-> valence e- are further from the nucleus=weaker pull=atom will not hog shared electron.

When going across-electronegativity will increase.

Why?

-> valence e- are closer to nucleus=stronger pull=atom will "hog" shared e-.

The Periodic Properties Review sheet is under the Unit 3 Periodicity Assignments. If you click on it, all the questions are answered and done for you. If you don't understand any of the questions, be sure to look back at all the worksheets we were given (pages 1-13) will help, also look through the fill in the blank worksheets we did in class. If you want extra practice or more to review print the Periodicity Practice Exam under the Unit 3 Periodicity Assignments.

*Remember: if you're having trouble always go back to atomic size.*

Also: The test is tomorrow and and the lab test was moved to Wednesday.