Chemical Equilibrium

Hey everyone! I guess I have to scribe for today because no one's been doing it lately! 

okay lets start.. 

Lately we have been learning about Chemical Equilibrium. 

What we did last class was learn about "Le Chatelier's Principle" 

This principle states that "When the system at equilibrium is subjected to stress, the system will adjust so as to relieve the stress." 

Changing of Concentration

In a system, a change in the concentration of products or reactants present at the equilibrium, combine to form a stress. At equilibrium, the ratio of products to reactant concentrations is constant. 

When adding more reactant or removing of the products, it would upset the equilibrium. 

To relieve the stress, you need to form more of the products or use up the reactant. 

note: 

a) Increasing the concentration of a reactant shifts an equilibrium to the products (or right hand) side because the rate of the forwards reaction is increased. 

b) Increasing the concentration of a product shifts an equilibrium to the reactant (or left hand) side because the rate of the reverse reaction is speeds up. 

c) Decreasing the concentration of a reactant (by removal or by compounding it with something else of by precipitation) shifts an equilibrium to the reactants (left hand) side because the forwards reaction is slowed down. The reverse reaction will 'overtake' the forwards reaction. 

d) Decreasing the concentration of a product shifts an equilibrium to the products (right hand) side because the reverse reaction is slowed and the forward reaction 'overtakes'. 

 

Pressure Changes 

N2O4(g) <-----       ----->2NO2(g)

                                                      Very light yellow, almost colorlesss              Brown 

Increases pressure will cause more collisions to take place between gaseous molecules (pressure is a measure of the number of particles per unit volume). 

• An increase in pressure will favour the reaction involving the most particles. 
• An increase in pressure favours 2NO2 molecules reacting more than one N2O4 reacting. 
• The reverse reaction speeds up. 
• The equilibrium shifts to the left hand side.    Ex. A lighter color is produced, after an expected initial darkening caused by the original color being 'compressed'. 

If the pressure is decreased, the initial color thins but rapidly darkens. The equilibrium has shifted to the right hand side because the reverse reaction has slowed down. The collisions have been reduced in frequency. 

Pressure changes only matter if there is a different number of gas molecules on each side. Pressure changes are irrelevant if there are no gas molecules in the reaction. 

Ex. 

H2(g) + I2(g) <----     ----> 2HI(g)

There is no change in Equilibrium position. 

Temperature Change 

An increase in temperature speeds up an reaction. An endothermic reaction is helped more by a temperature rise than an exothermic reaction. 

Endothermic

N2O4(g) <---------                 ---------> 2NO2(g)

                                                      Dinitrogen tetaoxide              Exothermic            Nitrogen Dioxide 

                                               ( very light yellow, colorless )                                                   ( brown ) 

• Increasing temperature will favour the forwards reaction more so that the reverse, and so the color darkens and the equilibrium shifts to the right hand side. 
• Decreasing temperature slows the endothermic reaction the most, and so the forward reaction slows drastically and the reverse reaction wins, which means that the color lightens as the equilibrium shifts to the left side. 

Effect of a Catalyst 

A catalyst makes an easier path for the reaction, the path for the reverse reaction is made equally easier. A catalyst will not shift an equilibrium position because both rates are equally increased. The equilibrium is achieved quicker in time and under easier conditions.

However, 

If a catalyst is added to a system which is not at equilibrium, the system will reach equilibrium much quicker since forward and reverse reaction rated are increased. 

Well, I think that's basically what we learned on Monday. 

Remember to do all your worksheets and have a good day everyone! 

The next scriber will be..... ARI5 ! =)   

hey guys ok so i'm going to be doing the blog post for the past few classes since i forgot to do it last week =\.

ok so to begin,

by examining the change in amount of substance at a particular time or over a period of time, the rate of reaction can be determined. The representation of such a reaction may be seen as the following once recorded onto a graph:














In order to calculate the rate we would use the formula:
RATE =

(final concentration of A) - (initial concentration A)
__________________________________

final time - initial time

- OR -

RATE = [A]final - [A]initial

_________________________

[t]final - [t]initial

INSTANTANEOUS RATE: of a reaction at a specific time is determined by calculating the slope of the line tangent to the point on the concentration vs time curve.

We also learned two types of reactions, exothermic and endothermic.

EXOTHERMIC: the product possess less energy than the reactants, during the reaction heat is lost from the system and (delta)H is a negative value.

ENDOTHERMIC: the product possess more potential evergy than the reactants, this energy is absorbed from it's surroundings, increasing the system's energy content, giving a positive (delta)H value.

ok so thats pretty much what we have been duscussing, on monday Mrs. Kozoriz, wasn't there but the sub gave two worksheets one we finished in class (reaction rate 52; CHANGE IN H2O0 WITH TIME) and one we had to work on for the rest of the class (reaction rate 17; A model for reaction rates).

THE NEXT SCRIBE WILL BE........... hm........ lucky : *****Niwatori-san******

Monday November 3/08

HEY everyone!!!
I am truely sorry about the very late post, my internet was down and i couldnt do anything last night. ANYWHO,
Yesterday in class, was just a work period. We had to finish the analysis from the lab. And if you haven't done the lab yesterday was the chance.
Ms.k gave us a word search to do if we were done.
either than that, i don't really know what to right because it was just a work period.

Sorry Ms.K, i know you dont like these kinds of blogs, but i dont know what to write. (or in this case type)

christine will be be the next blogger =)

Experiment: Part I

Hello there!!

Okay, so what we did today is the experiment:

Factors affecting the rate of a reaction.
Materials:
24-well test plate
HCl Solution
Water
Zinc Nitrate Solution
Iron Nitrate Solution
Acetic Acid
Copper Nitrate Solution
Toothpicks

And a few pieces of the following:
Magnesium
Aluminum
Zinc
Copper
Iron

Part I:
1.) Add 20 drops of 3.0 moL/L HCl Solution to each of five wells of the 24-well test plate.
2.) Place a small piece of Mg in the first well, a piece of Al in the second, a piece of Zn on the third, a piece of Fe in the fourth, and a piece of Cu in the fifth.
3.) Observe and Record your observations.
Questions:
1.) What gas is produced? How do you know?
2.) Write a balanced equation to represent the reaction.
3.) Do all the metals take the same time to react?
4.) Rank all the metals in order of reactivity.
4.) Add 13 drops of water and 7 drops of 3.0 mol/L HCl solution to one well. Use the toothpick to stir the solution.
5.) Add 13 drops of water and 7 drops of 3.0 mol/L Acetic Acid to a second well. Stir.
6.) Add 20 drops of 1.0 mol/L aqueous Zn(NO3)2 solution to a third well, 20 drops of 1.0 mL/L Fe(NO3)3 to a fourth well, and 20 drops of 1.0 mL/L Cu(NO3)2 to a fifth well.
7.) Place a small piece of Mg in each of the five solutions.
8.) Observe and Record your observations.
Questions:
1.) What happened in each test tube? I dentify the products in each case.
2.) Write a balanced equation to represent each reaction.
3.) How much time does the Mg take to react in each solution?

The next blogger is Angela!

Atomic Structure Test

Atomicstrucutretest

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The Review..."Ëlectrons in Atoms"

Hola !!! hello everyone!!! this is Maria scribing for Tuesday's class.... This will be a short recap for the review on the test tomorrow.

Light and Quantized Energy

>Electromagnetic radiation. is a kind of ENERGY that behaves like a(n) WAVE as it travels through space.
--- Light is one type of electromagnetic radiation, others ex. include: X rays,
All waves can be characterized by their wavelength, amplitude, frequency,and speed.
>Wavelength.. is the shortest distance between equivalent point on a continuous wave.
>Amplitude.. is the height of a wave from the origin to a crest or from the origin to a trough.
>Frequency.. is the no. of waves that pass a given point in 1 second.





the photo shows the wavelength and the amplitude.






---A (n) Quantum is the minimum, amount of energy that can be lost or gained by an atom.---

Quantum Theory and the Atom.

1. Ground State. the lowest allowable energy state of an atom.

2. Bohr's Model of the atom predicted the FREQUENCIES of the lines in hydrogen's atomic emission spectrum.
3. According to Bohr's atomic model. >the smaller an electron's orbit, the lower the atom's energy level.
4. Also the larger an electron's orbit, the higher-energy orbit.
5. Bohr proposed that when energy is added to a hydrogen atom, it's ELECTRON moves to a higher- energy orbit.
6. ---- the hydrogen atom emits a photon corresponding to the difference b/w the ENERGY LEVELS associated w/ the 2 orbits transitions b/w.
7. Bohr's atomic model failed to explain the atomic emission spectrum of elements other the Hydrogen.


ex. Bohr's atomic model

QMM (Quantum Mechanical Model ). the modern model of the atom that treats electrons a waves.
Atomic Orbital. a three-dimensional region around around the nucleus representing the probability of finding an electron.

The difference b/w Bohr model and QMM(Quantum Mechanical Model ).
QMM treats electrons as waves and does not describe the electrons paths around the nucleus.
Bohr model treats electrons as particles traveling in specific orbits.














Electron Configurations
>The arrangement of electrons in an atom < style="color: rgb(204, 102, 204);">Ground-State Electron Configuration.
--3 Rules define how electrons can be arranged in an atom's orbital.--
Aufbau Principle. states that each electron occupies the lowest energy orbital available.
Pauli Exclusion Principle. states that a maximum of 2 electrons may occupy a single atomic orbital, but only if the electrons have opposite SPINS.
Hund's Rule. states that a single electrons with the same spin must occupy each equal-energy orbital before additional electrons w/ opposite spins occupy the same orbitals.


Well folks good luck on tomorrows test!!! the next blogger will be...............

• NCC-74656 Intrepid Class...

Electronegativity worksheets.

Hello Everyone! 

In todays wonderful chemistry class we worked on the three worksheets that we had to do over the weekend! 

Just in case you missed out on some of the questions, here are the answers : 

Worksheet 1 : Determining Electronegativity difference and Percent Ionic Character. 

1. a) 2.23 b) 1.27 c) 0.58 d) 1.26 e) 0.68

2. (A) Na and Cl would be considered ionic. 

3. % ionic character, electronegativity difference - direct relationship 

4. a) 70% b) 36% c) 10% d)33% e)12% 

5. ionic percent + covalent percent = 100 

6. a) 30% b) 65% c) 90%  d) 67%  e) 88%

Worksheet 2: Section 6.3 Periodic Trends 

1. (C) 2. (C) 3. (D) 4. (B) 5. (A)  6. (A) 

7. Ionization energy is the energy required to remove an electron from a gaseous atom. 

8. A high ionization energy value is not likely to form a positive ion because it has a strong hold on its electrons. 

9. first ionization energies increase as you move from left to right across a period because as you go across the period, the nucleus hold on to its electrons more tightly. 

10. In a group, first ionization energies decrease as you move down a group. This decrease in energy happens because atomic size increase as you move down the group. The valence electrons farther from the nucleus, less energy is required to remove them. 

11. * don't have. 

12. It indicated the relative ability of its atoms to attract electrons in a chemical bond. 

13. Electronegativy increase as you move from left to right across a period and decrease as you move down a group. 

Worksheet 3: Section 9.5 Electronegativity and Polarity

1. Its the ability to attract electrons in a chemical bond. 

2. Fl,  3.98,  Halogens,  group VII A 

3. Fr,  0.7,  Alkali metals,  group I A 

4. Group -> decreases Period -> increases 

5.  > 1.70 = ionic bond  < 70 =" covalent">

6. True

7. False 

8. (C) 9. (D) 10. (B) 11. *don't do*  12. (C) 13. (B)

14, 15, 16, 17.  *don't do* 

Here are the answers to our awesome and fun worksheet! =) 

After going over the worksheets we got a review that is needed to be done by tomorrow! 

Make sure that everyone studies because the test will be on WEDNESDAY, OCTOBER 22 2008! 

GOOD LUCK EVERYONE! =) 

next scribe is...  M

Atomic Structure: Electronegativity

Hello everyone, this is Nelsa blogging for Friday's class! This time, I'm going to save after every sentence. I am not going to go through losing everything again.

Soo, let's get to the point.


I. ELECTRONEGATIVITY

electronegativity: Indicates the relative ability of its atoms to attract electrons in a chemical bond.

Basically, as you move across the periodic table - from left to right - electronegativity increases, and as you move down the periodic table, electronegativity decreses.

In grade nine (.. or last year), we were told that a bond between a metal and a non-metal is ionic, and a bond between two non-metals is covalent. That's still true for the most part, but on Friday, we found out why that's true. Chemical bonds between different atoms are never completely ionic or covalent, and what type of bond it is depends on how strongly the bonded atoms attract electrons.

We'll need the electronegativity difference to figure out the character of the bond. Having a difference of 1.70 is considered 50% covalent and 50% ionic. A number that's greater than 1.70 is then considered ionic and a number that's less than 1.70 is then considered covalent.



II. IONIZATION ENERGY

ionization energy: The energy required to remove an electron from a gaseous atom.

An atom with a high ionization energy value has a strong hold on its electrons, which means they are less likely to form positive ions. The opposite is true for atoms with a low ionization energy value.

When you move across the periodic table - left to right - the ionization energy increases, and when you move down the table, the energy decreases.



III. ATOMIC RADIUS

The electron cloud surrounding a nucleus doesn't have a clear edge, therefore the atomic radii can't be measure directly.

atomic size: How closely an atom lies to a neighbouring atom.

For metals, the atomic radius is half the distance between adjacent nuclei in an element [d/2], and for elements that occur as molecules, the radius is half the distance between nuclei of identical atoms that are chemically bonded together.

As you move across the periodic table - left to right - the atomic radii decreases, and it increases as you move down a group.



IV. IONIC RADIUS

When atoms lose electrons and form positively charged ions, they become smaller. When atoms gain electrons and form negatively charged ions, they become larger.

Moving across the periodic table - left to right - will decrease the size of positively charged ions, and increase the size of negatively charged ions. The ionic radii of both positive and negative ions increase as you move down the table.


That's basically a summary of what was on those sheets that (you should) have gotten on Friday. Mm, we were given two worksheets for homework, and one that we did in class together.

Yeah.. that's it! I hope you guys had a good weekend. Happy Monday! xD

Next scribe will be ALVINA.

Electron Configuration (shortcut)

Last class we learned how to write however many electrons in which orbitals and whatever sub-levels, and taking oxygen as an example, this is how it looks like:

But guess what, there's a shorter way to write this!!It looks like this:

Yeah, I also found it weird that oxygen had helium in it's title .. O_O


So to teach you guys how to do this technique, I shall show you this diagram:











Erm .. I just realized now that I shouldnt have blocked the names of the noble gases .. but I worked freakin hard on this, so too late to redo it.
so you should hold a periodic table on you


The periodic table is arranged so that all the S's, P's, D's and F's are together. AIN'T THAT NEAT ?!
I did the colors like how it is in our periodic table. All the elements in the shaded purple area, are S's, all the elements in the shaded orange area are D's, and so on.

Lets take this slowly.
Look at the element you want to name
1)You start at the first noble gas before that element (see diagram/periodic table)
- and the journey begins!
2)You write down your journey from the noble gas, to your element.
HOW DO YOU DO THAT?!
- every color you pass by, is a checkpoint. At the checkpoint, you write the row number (black numbers on the side),
3) then you write whats shown above it. =) .. ..
..
..
..
EXAMPLE If you didn't understand anything up there, ignore it, and you'll get it here. (hopefully)
Look at the oxygen example I did up there.
1) The noble gas before oxygen, is HELIUM
[He]
2) Now on your journey you go till the end of the purple area. CHECKPOINT!.
At Be, Look to your right, "2" then above you "s^2"
[He] 2s^2
3) Now move to the yellow area, and reach the finish line! O!
Go to the O, look to your right/left "2" look above you "p^4"
[He] 2s^2 2p^4
Hense, :
Lets do two more examples.
Oxygen was easy.
Lets do a medium,
THEN A HARD!

EXAMPLE 2: Gallium
1) Noble Gas: Ar
[Ar]
2) Purple Checkpoint
[Ar] 4s^2
3) Orange Check Point
[Ar] 4s^2 3d^10
4) Finish line
[Ar] 4s^2 3d^10 4p^1:



EXAMPLE 3: Gold
1) Noble Gas
[Xe]
2) Purple Checkpoint
[Xe] 6s^2
3) GREEN CHECKPOINT
[Xe] 6s^2 4f^14
4) Finish line
[Xe] 6s^2 4f^14 6d^9:



*DON'T FORGET THE GREEN AREA! The F's! It fits in after Barium, number 57 =)*




I don't like blogging, because I never have time for it, so I always usually start around midnight, and I'm a perfectionist when it comes to blogging. I go over it dozens of times making sure it makes sense, I draw pictures on all kinds of photo editing stuff, I emphasize and group stuff to make it appealing to the eyes, so you're not looking allover the place.
I'm a complex person. PLEASE DON'T CHOOSE ME TO BLOG NEXT!

Oh, and next blogger will be .. NELSA :)

Electron Configuration

Okay so its my turn to blog, but today was confusing a bit so i might not do a good job.
Today we learned about electron configuration.

Which is about how energy levels of electrons are designated by principal quantum numbers(n)
each energy level is divided into sublevels. in each level maximum # of electrons is set. we name each level, and the 1st level is called 1s (s for sublevel)
ahhh so hard to explain>>>
in each orbital we can fit 2 electrons.
okay so in "S" we have 1 orbital.
when we reach a higher level we name it differently like 2p which has has 3 orbitals
so the diagram would be.
S= 1 orbital
p= 3 orbitals
d= 5 orbitals
f= 7 orbitals

1s²
1= 1 level
s= number of orbitals
2= number of electrons.

example:
1s², 2s²
which would mean 1st level has 2 electrons which fills the whole orbital
2nd level had 2 electrons but only fills 1/3 of the orbitals.

I hope this helped cuz i didn't understand it at first.
Angela to scribe tomorrow!

Atomic Structure

The class did 2 experiments on spectroscopy. They viewed gas discharge tubes through spectroscopes to see the line spectrum that is produced. Hydrogen, helium, mercury, nitrogen, oxygen, and strontium were some elements that were viewed. The line spectra was reproduced on the lab sheet.
Another lab that was done in class was to produce cool blue light. Students mixed luminol, perborate and copper sulfate in a beaker of distilled water. When the copper sulfate was added, the chemical reaction started. With the lights out in the classroom, the colour in the beaker was a blue luminescent one. This was an example of chemiluminscence.
We also covered the historical aspect of the quantum theory-read some bio's of the scientists involved in developing this theory.
Also saw a neat simulation showing an electron absorbing a certain amount of energy (photon) and travelling to an outer orbit. When the electron fell back to a lower orbit it gave off the energy in the form of coloured light.

Today in class ...

So today in class we worked on those work sheets and did the questions on oxidation and reduction and the " O.A & R.A " .. Agents .. I honestly hate that balancing thing it's soo hard ! .. um i don't really know what else to say soo good luck on the test everyone !

next scribe is Ari5

Identifying Redox Reactions

Redox

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Chem with Niwatori-san! =p

well so far we covered our unit learning as quoted by Antony-san
Ternary Nomenclature: Acids and Bases
Solubility
Identification of Unknown Solutions
Equations: Ionic, Net Ionic
Concentration, Titration, Neutralization
Moles, Volume




so from here we cleared a unit woo now we got 5 more units to cover so now is the time to pick up the pace people! Let's work hard in the future travels in chemistry!

This unit was finished today with a Test so hopes for the people who missed it come to Ms . K right away and ask for that test somehow!


LABS LABS LABS until we get into our heads as scientists we are hah! Better leave that to Ms. Kozoriz while we just do the experiments and the work included. Oh yeah next time let me get a scribe role where it isn't the test day people -_- dude this is like my second Test scribe once for physics now one for chem jeez what a coincidence huh? -_-

Oh well... luck of the draw.. =p

GAMBETE PEOPLE!! (gambete japanese for go for it! or work hard!)

next scribe is AngelaG *clap clap clap* (passes baton to her) "have fun!" ^o^

Where is the Next Blogger?

Okay, so since no one is blogging....

I'll blog for today...

We had a test today(again..:-)) about:

Ternary Nomenclature: Acids and Bases
Solubility
Identification of Unknown Solutions
Equations: Ionic, Net Ionic
Concentration, Titration, Neutralization
Moles, Volume

.....Titration Lab.....

Helooooooooo!!!!!

Today, we continue to answer the following questions on the titration lab booklet.

The purpose of this lab is to determine the unknown concentration of substances.


Photo of concentration of sodium hydroxide to a test tubes containing a known concentration on sulfuric acid until it becomes pink.

And last but not the least a short video about the titration......lab
CLICK HERE....
i guess i have nothing 2 say.



Well, DON't FORGET 2 answer the booklet it's due TOMORROW.







NEXT SCRIBE IS................Niwatori-san......

Titrtation Lab

Hello...

Okay, so what we did today (and also learned) is the Titration Reaction (Lab. or Experiment...)

Titrations are procedures which are usually used to determine the unknown concentrations of substances . It is a common laboratory method of quantitative/chemical analysis that can be used to determine the unknown concentration of a known reactant. Because volume measurements play a key role in titration, it is also known as volumetric analysis. A reagent, called the titrant, of known concentration (a standard solution) and volume is used to react with a solution of the analyte, whose concentration is not known in advance. Using a calibrated burette to add the titrant, it is possible to determine the exact amount that has been consumed when the endpoint is reached. The endpoint is the point at which the titration is complete, as determined by an indicator.

THE EXPERIMENT
Materials: 1-50mL beaker
3 Micropipettes
Phenolphthalein Indicator
10 mL Graduated Cylinder
Distilled Water
0.1 mol/L NaOH
0.1 mol/L H2SO4


Procedures:

1.) Using the Graduated Cylinder and a micropipette, count and record the number of dropd required to obtain 1.0 mL of distilled water. REPEAT the process 3 TIMES.

2.) Add 5 mL of Distilled water, and 1 drop of Phenolphthalein Indicator to the 50 mL beaker.

3.) Using a 2nd micropipette, add 20 drops of 0.1 mol/L H2SO4 to the beaker.

4.) Using the 3rd micropipette, add the 0.1 ml/L NaOH drop by drop until the addition of one drop permanently changes the colour of the solution. Recprd the number of drops required to reach the endpoint of tartration.

5.) Rinse the contents of the beaker. "Repeat Steps 2-4 a total of 3 times!!!!"

The Next 'Blogger' is M:-)

Two Days Befor My Birthday!! a.k.a sep 16th :)

OK SO todayyyy we looked at page 7 in the YELLOW booklet thing.

Page 7:

What volume of a 0.250 ml/L solution of carbonic acid is needed to neutralize 30.0g of sodium hydroxide?
Q1: write the nutralization reaction
A1: H2CO3 (aq) + 2NaOH -> Na2CO3(aq) + 2H2O(s)
Q2: Determine the number of moles of base.
A2: 30g NaOH x (1mol NaOH/40g NaOH) = .75 mol NaOH
Q3: Calculate moles of H2CO3 Needed to neutralize the base.
A3: 1mol acid 2 mol base
.375 mol acid .75 mol base
Q4: Calculate the volume of H2CO3 required
A4: V=n/c = (.375 mol H2CO3)/(.250 mol H2CO3)
V=1.5 H2CO3(aq)

WE ALSO GOT a NEw booklet on Neutralization Reactions and did the questions on the back of the booklet :D

It was overall a productive day andd personally, i don't understand what we covered ... But its not too too bad .

OH!!! AND we had a lock down in effect and ppl were yelling i the halls and so on so that was kinda the most interesting peek of the class :)


NEXT SCRIBE IS ***NCC-74656***

scribe post

Hey guys,

ok so today in class we learned how to Write Ionic and Net Ionic Equations.

Q: why is a "total ionic equation"?
A: Because every spieces which breaks down into it's ions when dissolved in water has been written in ionic form.

Q: What is a "net ionic eaquation"?:
A: an equation that includes only those compounds and ions that undergo a chemical change in a reation which occurs in aqueous solution; shows the reaction that occurs, omitting the spectator ions.

Vocbaulary:
Spectator: ions found in solutions both before and after a chemical reaction; they "watch" the reaction occur.
Salt: a compound composed of the negative ion of an acid and the positive ion of the bases.

so off the sheet Ms. Kozoriz gave us today titled:

"Summary of Writing Total Ionic and Net Ionic Equations"

it shows the 7 steps in writing these equations. These steps are:

STEP 1: identify type of reaction and possible products.

STEP 2: look up solubility of both products.

STEP 3: Indicate states of reactants and products.

STEP 4: Write chemical equations for reaction.

STEP 5: balance the equation.

STEP 6: Write total ionic equation.

STEP 7: Write Net Ionic Equation.
(on that sheet we are given two different examples which follow these steps.)


WHAT IS NEUTRALIZATION?
Neutralization: a neutralization reaction is one whose products are a salt and a water.

aN equation such as:
ACID + BASE -----> SALT + WATER

CALCULATING AN UNKNOWN CONCENTRATION:
We would follow the 4 steps:

1) write the balanced neutralization reaction

2) calculate the number of moles of the solution. (stoichiometry)

3) calculate the moles of acid/base used.

4) calculate the concentration of the acid/base.

Using the formula:

concentration = n / v (moles / volume)

We can solve questions to determine the amount of acid of base needed to neutralize the solution:

** calculate the concentration of hydrochloric acid, if 25.00 mL is just neutralized by 40.00 mL of a 0.150 mol/L sodium hydroxide solution.



1) HCl(aq) + NaOH -----> H2O(l) + NaCL(aq)

2) (moles = c x v)
= 0.150 mol/L x 0.040L
= 0.006 mol NaOH

3) moles of HCl = moles of NaOH

4) (c = n / V)
= 25 mL x (1 L / 1000 mL) = 0.025 L
= 0.006 mol HCl / 0.025 L = 0.24 mol/L HCL

ok that's about it. i was working on the lab during class so i'm still reading over todays notes. so for anyone whose having problems if you don't get it try reading the notes it can be found in the yellow booklet (pages 4 - 6) and i believe i recall Ms. Kozoriz assigning page 7 for homework so just incase might wanna work on that!

the next scribe will be the_bdl

SORRY

Well Hello Fellow Classmates.

SORRY for the late blog, something was wrong with my computer and my dad just fixed it =/
SOO thanks for waiting =)

First thing we did was we went over one of the homework pages.
Which was Reactions In Aqueous Solutions


Well on friday we did a lab called The Aqueous Lab
we had to make equations inorder to find out 4 solutions.
We also could try to find it out by mixing solutions together.

ANYWAYS, i dont know what else to write, but im pretty sure thats all we did on friday..
sorry once again for the late post! =)
AND next to scribe is CHRISTINE

Labs Are Fun.. When Something Happens

Hello everyone, my name's Nelsa, and I'm apologizing for the late/early post. I could sit here for fifteen or so minutes telling you all about the happenings of yesterday that prevented me from blogging.. but I won't because that's just not cool, and you guys probably don't care anyways.. SO. Moving on.

Yesterday, we had a lab where we had a whole bunch of chemicals that we mixed together. The point was to figure out which ones formed a precipitate. Most of them did not form a precipitate, sadly, but me and Angela were hopeful all the way, hahaha.

That was basically the whole class. We received some.. solubilty charts/tables/lists, whatever floats your boat, and I believe she told us that we'll be using them today. Hmm. Oh and also, buy your periodic tables for $0.50! They're so nice and colourful. =)

So that's it. I swear I make better posts than this, it's usually more thought out, but I'm rushing right now. NEXT TIME. Oh btw, *quick look at scribe list* next scribe shall be Christine. Hopefully you see this? =/

chem. 09/08/08

Today in chem. class we learned something new, aqueous reactions.

Most of today's lesson consists of precipitation reactions.

Ms. K showed us how ionic compounds when put into water, dissolve.

When you have a solution that involves a chemical change in color, heat, odor and gas forming are usually called precipitating reactions. ( double displacement reaction, when two aqueous solutions are mixed ) Chemical reactions are occurring

I think we went over a little bit on net ionic equations and spectator ions.

She also showed how the certain chemicals moving together.

I think it was lead and nitrate ions moving around in the beaker and when the iodide and potassium was added with the lead and nitrate ions, it first moved randomly all around. Then iodide and lead started to form a big cluster of ions. Once it got big enough, the particles started to sink to the bottom. This was the part where you can notice substances floating on the bottom.

Tomorrow we're all going to start on a lab assignment on developing solubility rules. It to see if certain chemicals create a precipitation reaction or not.

I think i can remember certain things being said in today's lesson. I know for sure that my last year chemistry teacher went over this because i have already did this lab before. ( if its the same one I'm thinking about)

Well that's all i can remember from today's class.

Alvina

Scribe List

This is The Scribe List. Every possible scribe in our class is listed here. This list will be updated every day. If you see someone's name crossed off on this list then you CANNOT choose them as the scribe for the next class.


This post can be quickly accessed from the [Links] list over there on the right hand sidebar. Check here before you choose a scribe for tomorrow's class when it is your turn to do so.

ALVINA(2) M Niwatori-san

nelsa Ari5 'Tiaa Melissa

AngelaG christine

NCC-74656 the_bdl