Post 4 Gas Laws

We did the airbag lab today that involved mixing baking soda and vinegar (5%) to produce CO2 in a bag. Starting this lab we found the volume of the bag by filling it with water before converting this amount (mL converted to L) into mols using the equation PV=nRT. After getting the mols, we used this number to find the grams of baking soda needed (stoichiometry) and the mL of vinegar needed (mols of vinegar x 20/1.05 [density]). After that, the lab was smooth sailing.

Post 3 Gas Laws

Other important laws include:
Charle's Law which involves temperature (in Kelvin) and Volume. It can be used in the equation V1T2 = V2T1.
*remember, when using temperature in Celsius, convert to Kelvin by adding 273.15
chemteam
 
Avagadro's Law uses volume and moles in a similar equation.
 Chemistry
chemteam

Finally, Combined Gas Law is a combination between Charle's Law and Boyle's Law using temp, pressure, and volume.
chemteam

Post 2 Gas Laws

Know certain laws that using different parts of the equation (P1V1)/T1 = (P2V2)/T2.
Boyle's Law leaves temp and mols constant while volume and pressure change.
nasa
khanacademy
Common units of pressure:

Post 1 Gas Laws

Characteristics of Gases:
- gases expand spontaneously to fill their container
- gases are highly compressible
- gases form homogeneous mixtures
- gas molecules are relatively far apart from one another and exert little influence on each other
chem4kids
purdue
And here's some extra details, just for fun.
mikeblaber
 

Post 2 Energy and Phase Changes

Here's some sources and practices.
youtube
youtube
hyperphysics
hyperphysics
boundless
boundless

 

Post 1 Energy and Phase Changes

Energy and phase changes are physical changes of state where intermolecular bonds are broken (not intramolecular bonds).
To determine this, use the equation q=mc∆t where q= thermal energy in J, c= specific heat capacity, and ∆t= change in temperature.

Post 4 Biodiesel

We burned some Chick-Fil-A oil to make our biodiesel fuel for the boats.

Our boat was made from coroplast which is also commonly used in signs and guinea pig cages (which is my personal use for it). We used a whole ton of hot glue to keep the boat water proof but on racing day it passed the line and a little over 22 sec.

Here's some boats in action: youtube
                                              youtube

Post 3 Biodiesel

Today is a free blog day so I decided to do some extra research on the putt putt boat project. Most noticeable in its appearance in the movie "Ponyo", the putt putt boat is a simple powered, miniture model.
Here's a website that explains how the boat runs and works. sciencetoymaker
And here's a website that explores the differences between multiple fuel sources. consumerreports
Tomorrow we'll be starting the project that involves making a boat and racing it against each other.

Post 2 Biodiesel

We are now starting a new project on putt putt (pop pop) boats.
Here's a website I found most useful on how to make a putt putt boat. nmia
Here's another website with instructions. allencentre

Post 1 Biodiesel

Our new topic is biodiesel, and we recently did a project to raise awareness of using biodiesel through a video.
Here's a link to our video. youtube
Here's the website. biodiesel

Post 4 Chemical Bonding

We had a fun pancake party to celebrate the last day of school before spring break!

And here's a site that reviews over the lectures of this unit.
chem1

Post 3 Chemical Bonding

We did an easy lab that went over chemical bonds by showing us the 3d version of the compound compared to the Lewis structure. As such, it helped us draw diagrams as well as determine the shape created.
 
Here's an example of our work.

Post 2 Chemical Bonding

Resonance is when more than one Lewis structure can be drawn. As such, compounds must have multiple bonds and when you move the bond (double), the neighbor must be able to take the bond like in cases where H can only have one bond and thus can't double bond.
An introduction to this is shown by chemwiki.
Also know the difference in vocab as molecular shape is the molecular geometry (shape) and electronic geometry is determined by the element (lone pairs of electrons and bonds).

Here are some links from khanacademy that go over the unit up to this point.
drawing dot structures
formal charge and dot structures
resonance and dot structures

Post 1 Chemcial Bonding

Our newest lecture is over chemical bonding which involves the type of bonds as well as the shape of those elements as they bond. In covalent bonds, where bonds are shared rather than given or taken, elements can not be between a cation and an anion as this is an ionic bond, and thus this lecture doesn't apply.
First, when given a formula, make a have need share box in which:
H is the number of the element in that bond times the valence number (found in the periodic table).
N comes from the total electrons needed to be stable so you take the number of the element times 7 (where elements become stable but there are exceptions).
S determines how many bonds necessary by taking the added number of needs minus the added number of haves before dividing it by two because all bonds come in pairs of electrons.

The exceptions are:
H, He, Be = 2e-, B = 6e-, and elements in period 3 and beyond can have expanded octets including the major ones, the non-metals S, P, Xe, and Kr.

Here's some links to get into the unit:
hyperphysics

Post 4 Aqueous Solutions

As a reminder, here's some links that sum up the unit.
youtube
about
youtube
 

Post 6 Electronic Structures

We did another worksheet on the periodic table involving finding the different elements and where they would be place on the table. It was a fun but tedious task that involved 42 different elements in which we separated them through metal, metalloids, and non-metals. We then grouped them in columns based off of reaction in which Ah = Na (1+) and Ak = Cl (1-) before ordering them through density. We then fine tuned the chart by looking at ionization, which was the last thing we considered, and trying to keep certain elements we were already aware of in certain areas. In the end, our density across the periods were slightly off. Regardless, you can't help but respect those who have made the period table such an easy chart to maneuver.

Post 5 Electronic Structures

We did a lab involving wavelengths and small vials of liquid to measure the absorbance and %T (transmittance) of the said liquids. In doing so, we have discovered that A and %T have an inverse relationship in which the higher the A, the lower the %T. This corresponds with Beer's law.
 Absorbance = e L c in which e is the molar extinction coefficient, L is the path length of the cell holder, and c is the concentration of the solution.
 

Post 4 Electronic Structures

Orbitals:
s - spherical shaped
p - dumb-bell shape with x,y, and z axis
d,f - complex shapes
 
khanacademy

Rules for Placing Electrons:
Aufbau Principle: electrons enter orbitals of lowest energy first
Pauli Exclusion Principle: an orbital can only contain two electrons with opposite spin
Hund's Rule: within a sublevel, electrons enter singly before pairing up
chemwiki
kentchemistry

 

 

Post 3 Electronic Structures

A brief run down of periodic trends:
electronegativity: increases up, right
electron affinity: increases up, right
ionization energy: increases up, right
atomic radius: increases down, left
nonmetallic character: increases across, up, right
metallic character: increases across, down, left

Here's some websites:
chemwiki
chem

Post 2 Electronic Structures

Quantum Numbers:
n - principle quantum number, are generally the periods on the periodic table although they run as s (1-7), p (2-7), d (3-6), and f (4-5)

l - the angular momentum quantum number in which s=0, p=1, d=2, and f=3

m1 - the magnetic quantum number where s is 0, p (-1 to 1), d (-2 to 2), and f runs from -3 to 3

ms - spin quantum number, which represents where the valence electron lands on the orbital (either up or down) in
+1/2 and -1/2 respectively

 chemed

Post 1 Electronic Structures

We did the flame test lab that involved testing the color of flames, visible wavelengths, of different metals using a Bunsen burner. The flames were very pretty, ranging from pink to green, and we repeated this process with a glass filter.

We were given a mystery substance, unknown c, which, based on color, is most likely CaCl2. Using the colors, we then determined the wavelengths and used the equation E=h(c/wavelength) to get energy which is then multiplied by Avogadro's number to get J per mol.
Here's a demonstration that goes over a similar process as the lab. youtube
This goes into further detail and provides the wavelengths per color. smc

Post 6 Acid and Base

Today was the test which I found to be very difficult, but regardless here's a review over calculating the Ka from the pH and molarity.
chemwiki
Take the pH and convert this to molarity (H+) by using the equation 10 to the negative x power.
Take this number and square it (x^2), then divide it by the given molarity minus the pH's molarity (x).

Post 5 Acid and Base

The test is coming up for this unit so here's some things to go over.
Generic things to know:
chemed
clackamas
Finding Ka:
chemteam
Ice tables:
chemwiki 
And here's my notes on the most recent lecture about titrations.

Post 4 Acid and Base

We finished a second lab that involved a similar run as the first but we now had an unknown solid acid that we used. First we had to dissolve the solid in the water using heat before cooling it down and titrating it.

Here we placed it on a plate burner with a stirring rod.

Here it turns vibrant pink but the color begins to fade after awhile.

Post 3 Acid and Base

We did another vinegar lab that involved titrating KHP and vinegar samples using NaOH that turned the solution bright pink after mixing with phenolphthalein. It was the first time we used a buret, and it was difficult to control the drops, but regardless, it was a fun lab.
Here's the procedure:

 

1) Put on your splash-proof safety glasses, and keep them on throughout the lab.

2) Drain your buret into the waste beaker.

3) Rinse your buret with a small amount (several mL) of your NaOH solution, and drain into your waste beaker.

4) With the valve closed, add your NaOH solution until it is above the zero mark, and carefully drain until the meniscus is exactly at zero.

5) Obtain 0.5 – 0.8 gram of KHP, and record the mass to the nearest 0.001 g.

6) Transfer the KHP (without losing any) to the Erlenmeyer flask. Rinse the plastic tray with several mL of distilled water, and pour the rinse water into the Erlenmeyer. The goal is to transfer 100% of the KHP into the flask.

7) Add about 75 mL of water to the Erlenmeyer, and swirl to dissolve all of the KHP.

8) Add 2-3 drops of phenolphthalein.

9) Titrate the sample until a faint pink color remains, and record the volume of NaOH used to the nearest 0.1 mL.

10) Open up the vial with the blue cap. This vial contains commercial vinegar.

11) Pipet 10.00 mL of the vinegar into the Erlenmeyer flask. Dilute the volume to about 100 mL with distilled water, add two drops of phenolphthalein, and titrate with your NaOH solution. Record the volume of NaOH used.

12) If time permits, repeat steps 5-11.

13) Drain your buret, fill it with distilled water, and clean up you station.

Here's some websites that go over it.
khanacademy
chemwiki

Post 2 Acid and Base

Getting for the first quiz of this unit.
Acids [H+] and bases [OH-] together produce a salt and water. Acids produce conjugate bases and bases produces conjugate acids. These can then change through reactions.

When converting H+ to OH- use the equation H+ = Kw/ OH- in which Kw = 1.0 x 10^-14 and this equation can be used with OH- interchangeably

H+ to pH and OH- to pOH uses -log and going from pH to pOH would subtract 14.

Here's a link that provides information. mrwiggersci

Post 1 Acid and Base

We did another lab that involved the titration of vitamin c and iodine, which produced a clear color, and starch, which turned the solution blue to determine the concentration of vitamin c within different juices. Unsurprisingly, the grapefruit juice contained the most.

Post 3 Aqueous Solutions

Our latest unit includes both stoichiometry and molarity in calculations that, just like stoichiometry, convert volume (ml, L) using molarity (mol/L) into mols which are then converted into the new unit.
Here's a video that goes over it. youtube
Here's another website that goes over the step by step process of  calculating molarity using stoichiometry. yeahchemistry

Post 2 Aqueous Solutions

We have recently finished gathering the data for the murder investigation lab which involved double replacement chemical reactions, determining which reactions produced solids which when then used to determine that the mystery poison was silver carbonate. Here's a link to the lab. murder mystery lab

We discovered that the culprit was Mr.Green.
Here's a reminder on: double replacement youtube
                                   solubility rules chem 
                                   molarity occc , chemteam

Post 1 Aqueous Solutions

We did a lab that went over the concentration of stocks which involved diluting a stock of food colored water until the coloring had disappeared. Overall, it was a fun simple lab that got us into the new unit.

 Here's a website that goes over it. chemteam