Construction of an Air Bag Lab

So our only lab this unit (I think) is the construction of an air bag lab.

 Basically, we have to figure out how to inflate a plastic bag (size unknown) enough to where it can be pinched in but not enough to where it blows up.

We are utilizing vinegar and baking soda to produce the gas.

To figure out this amount of gas, we need to use stoichiometry and gas laws.

Here are some links is you need help with that:

https://socratic.org/questions/how-do-you-solve-a-gas-law-stoichiometry-problem

http://www.science.uwaterloo.ca/~cchieh/cact/c120/gastoichiometry.html

http://people.uwplatt.edu/~sundin/114/l114-17.htm

Reflection on the Quiz

Yesterday we took a quiz in class, and I don't think it went very well at all.

I am gong to make a post reviewing all of the stuff that was on the quiz that I did not know so that I know it for the test.

The first thing that was covered a lot was the kinetic theory of gases. The postulates are:

• Gases consist of small particles (molecules) that are in continuous, random motion.
• The volume of the molecules present is negligible compared to the total volume occupied by the gas. 
• Intermolecular forces are negligible.
• Pressure is due to the gas molecules colliding with the walls of the container. 

The rest of the questions that stumped me were mostly just logic and conceptual, so I can't really post anything that would help with that.

Hopefully your quiz went better than mine!

Avagadro's and the Combined Gas Law

Avogadro's Law tells us for that a gas at constant temperature and pressure, the volume is directly proportional to the number of moles of gas present.

Equal volumes of gas at the same temp and pressure will  have the same number of particles.

This holds true for gases at low pressures.

The mathematical formula for this law is V1n2=V2n1

*The volume of 1 mol of gas at STP (0 C or 273.15 K) is 22.4L.

-------------------------------------------------------------
The combined gas law is the only law with 6 variables.

This is a combined formula of all the gas laws when all variables change.

The mathematical formula for this one is P1V1T2=P2V2T1

Here are some links if you need more help:

http://www.chemteam.info/GasLaw/Gas-Avogadro.html

http://www.chemistry.co.nz/avogadro.htm

http://www.chemteam.info/GasLaw/Gas-Combined.html

Charles' Law

The next law we learned about is Charles' Law

This law tells us that temperature and volume vary directly with each other at a constant pressure.

The temperature for this law must be in Kelvins, but to convert C to K all you have to do is add 273.15.

As temperature increases, the gas wants to expand, and since pressure is constant, it can only increase in volume.

The mathematical formula for this is V1T2=V2T1

Absolute zero, or where there is no kinetic movement at all, is -273.15 C.

Boyle's Law

Today we learned about the first gas law, Boyle's law.

It tells us that the relationship between pressure and volume is inverse.

It holds a constant temperature and only deals with pressure and volume. 

But, the only gas that holds strictly to this relationship is an ideal gas at low pressures.

The mathematical formula for this law is P1V1 = P2V2

Intermolecular Forces

Intermolecular forces are forces of repulsion or attraction between neighboring molecules. They are weak compared to the intramolecular forces, the forces which keep a molecule together.

Weakest to strongest, they are London dispersion, dipole dipole, hydrogen, & ionic bonding.

Here is a simple picture illustrating how to determine which type of bonding is present.

Another thing to remember is that stronger intermolecular forces result in higher boiling points, seeing as the bonds require more heat to be broken due to their strength. 

Here are some links I found helpful:

http://chemistry.bd.psu.edu/jircitano/IMforces.html

http://www.chem.ucla.edu/~harding/notes/notes_14C_noncoval02.pdf\

Heating Curve and Phase Diagrams

In this unit there are two main graph/image based pieces of information: heating curves and phase shift diagrams.

Here is the heating curve. It is important to note that you calculate energy from A-B, C-D, and E-F by mc^T. B-C is mLf and D-E is mLv.

Here is the phase shift diagram. The first, top left section is solid, the central upper is liquid, and the lower right is gas. Point B is the critical temp and pressure and point A is the triple point, 

It is important to know how to read these graphs well in order to observe the behaviors of solids, liquids, and gases in different temperatures and pressures!

Here are some links so you can learn more: 

http://ch301.cm.utexas.edu/section2.php?target=thermo%2Fenthalpy%2Fheat-curves.html

http://www.kentchemistry.com/links/Matter/HeatingCurve.htm

http://study.com/academy/lesson/phase-changes-and-heating-curves.html

Back to the Basics

Before diving into this unit, it is really important to know the basic information on solids, liquids, and gases! It is, after all, what this whole unit is based off of.

Here are the basics:

Gas:
Spread out
Particles move very quickly/sporadically
No definite shape

Liquids:
More compacted than gas
Particles move slower, vibrating
Takes shape of container

Solids:
Particles very close together
Little to no movement
Has definite shape


You should also note that on phase change diagrams, the order goes solid, liquid, and then gas from left to right as it is traditionally ordered.

Here's a helpful video https://app.schoology.com/course/309537052/materials/link/view/548386589

Biodiesel Lab

For our biodiesel lab we are engineering put put boats that run off of the biodiesel we create in lab!

The lab itself isn't very hard, but creating the put put boat was actually extremely difficult.

Here are some pictures of our lab:

Overall, I thought this was a super fun lab and I learned a bit more about what biodiesel really consists of!

Finished video

Today we finished our video for the biodiesel contest!

We did end up using Powtoon to make our video and I think it turned out pretty good.

Here's a link to our submission on youtube in case you wanted to check it out:

https://youtu.be/biqN5kinpR4

Biodiesel Project

For an into to our Biodiesel unit, we are compiling a video to inform people about biodiesel. We are going to enter this into a competition hosted by the American Lung Association.

Today in class we received a really informational pamphlet about biodesiel, so I think we are going to incorporate that somehow. 

Also, I think we have finally decided that we are using Powtoon! It's a really good website to make animated videos that we cab voiceover.

If you want to know more about biodesiel, here are a few links:

http://www.biodiesel.com/

http://biodiesel.org/

http://www.afdc.energy.gov/fuels/biodiesel.html

https://www.fueleconomy.gov/feg/biodiesel.shtml

http://journeytoforever.org/biodiesel.html

http://nbb.org/

Test Day

Today we took our test over the Chemical Bonding unit and overall, I thought it went ok. I didn't have much time to study due to soccer and other issues lately, so I didn't feel as prepared as I could have walking into it.

There were a few questions on the test about covalent/ionic bonds, as well as some about polarity that I'm pretty sure I got wrong.

Overall, I thought the test was pretty straightforward and I'm hoping that that equals a good grade...but most likely not!

Hybridization

One of the things that we learned this short unit was hybridization in correlation to chemical bonding.

The name is a lot scarier than the actual process, I promise you.

All you need to do is count the number of electron domains, or places where potential bonds can occur on the atom, and put that number in the basic electron configuration model (spdf).

If you remember, S has 1 orbital, p 3, d 5, and f 7.

So if a bond has 5 electron domains on the structure, it has a hybridization of sp3d.

If a bond has 7 electron domains it would be sp3d3.

As this picture demonstrates, the hybridization corresponds with the electron pair geometry of a bond, due to both being determined by the number of electron domains.

Here are some links if you want more info:

https://chemistry.boisestate.edu/richardbanks/inorganic/bonding%20and%20hybridization/bonding_hybridization.htm

http://chemwiki.ucdavis.edu/Core/Theoretical_Chemistry/Chemical_Bonding/Valence_Bond_Theory/Hybridization

http://www.mhhe.com/physsci/chemistry/carey5e/Ch02/ch2-3.html

Also, here's a chem pun because it's funny. Ha. Ha.

Lewis Structures

The entirety of this unit is based on the ability to create the BEST lewis structure for each bond.

There are a few guiding rules to doing that,  ut mostly it is just practicing and trial and error.

One rule is that electronegative elements do not like to carry positive charges, so if one does it is most likely not the BEST structure.

Another rule is that charges on elements prefer to be spread out over the entire bond, instead of all piled onto one elements. For example, if one O in NO3 has a -3 charge on it while the rest are at 0, there is a better Lewis structure possible.

One more thing to make certain is that the charges on each part of the bond correspond with the overall charge. You can't have 2, -1 O's on a bond and have the overall charge be +4.

Here's a picture demonstrating this concept:

Here are some additional links if you want some more help:

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/lewis.html

http://www.chem.ucla.edu/harding/lewisdots.html

http://antoine.frostburg.edu/chem/senese/101/bonds/faq/simple-lewis-structures.shtml

Periodic Trends

The last thing we learned in this unit was periodic trends.  These trends include: electronegativity, ionization energy, electron affinity, atomic radius, melting point, and metallic character.

A super, duper easy way to remember these trends is this:

All trends increase up and to the right except for metallic character and atomic radius.

These 2 trends increase down and to the left.

Here's a picture to more clearly see the trends:

Quantum Numbers

Another way to name elements on the table is with quantum numbers. There are a total of 4. First there is t he Principal Quantum Number (signified by the letter 'n'). This can be found just by identifying which energy level the element is in.

The Azimuthal Quantum Number (signified by the letter 'ℓ') is based on the sublevel:

s= 0

p-1

d=2

f=3

The Magnetic Quantum Number (signified by the letter 'm' or mℓ) is also based on the sublevel. Depending on the number of orbitals, this will either be 0, -/+1, -/+ 2, or -/+3.

The Spin Quantum Number (signified by the letter 's' or ms) is based on the magnetic quantum number, but it is whichever number you run out of electrons on, when you're making the electron configurations. 1 electron is a +1/2 spin, 2 electrons is a -1/2 spin. 

Resources

I like to make one dedicated post a unit just for all the great resources I found. I feel like this makes it easier for people to sort through them and find which ones help. Here are all of the great sources I've been studying from:

http://sciences.unlv.edu/Chemistry/hatchett/pdf/103/CH09Solutions.pdf

https://edocs.uis.edu/hbapa1/www/CHE141/Flash/pdf/Chapter7.pdf

http://www.chemteam.info/Electrons/LightEquations1.html

http://www.chemteam.info/Electrons/QuantumNumbers.html

http://www.chemteam.info/Electrons/Video-given-ionization-energy-calc-wavelength.html

http://chemwiki.ucdavis.edu/Core/Inorganic_Chemistry/Descriptive_Chemistry/Periodic_Trends_of_Elemental_Properties/Periodic_Trends

Calculations with Energy

There are 2 very easy, yet important equations involved with finding energy, wavelength, and frequency.

One of them is:

The value of C is 3.0x10^8.

The second equation is E=h * f

E stands for energy.

h stands for Plank's constant, which is 6.63 * 10^-34

f stands for frequency, which can be calculated with the above equation. 

Light Spectrum

Additionally. being able to put the different sections of light in the light spectrum in order is crucial to understanding calculations.

The spectrum goes, in order of increasing wavelength and decreasing energy:

Gamma Rays
X-Rays
UV Rays
Visible Light
Infared Rays
MicroWaves
Radio Waves

Here's a visual depiction below:

Identifying Sublevels

The most important fundamental skill for this entire unit is being able to see a periodic table and label it accurately. 

For the unit, the table needs to be labelled into a s, p, d, and f group, as well as the primary energy levels.

On this periodic table here the red represents the s, with 1 orbital and 2 electrons. Yellow represents the p sublevel with 3 orbitals and 6 electrons. The blue represents the d sublevel with 5 orbitals and 10 electrons. Finally, the green represents the f sublevel with 7 orbitals and 14 electrons.

How to Find M of NaOH and M of Actetic Acid

On the test today there were 4 problems involving finding the average NaOH from a titration as well as the average concentration of Acetic Acid. The only problem was that I forgot how to do it. So here I am now making a blog post so that maybe I'll remember it for the final or something.

To find the concentration of NaOH, or the titrant, you take the moles of KHP, and divide it by the volume of NaOH used in the titration in L.

Since our reaction occurred with a 1:1 molar ratio, to find the concentration of acetic acid I just set up a MaVa=MbVb problem. (amount of vinegar)(x)=(M of base)(amount base used)

Unknown Acid Lab

One of the most stressful labs done this unit was the Unknown Acid lab. I think this is partly due to the fact that the power went out in the middle of our titration. 

The procedure for this one was similar to the vinegar and acetic acid lab. We standardized the NaOH and then titrated the unknown acid. The only difference is that this acid dissolved with heat so we used a magnetic stirrer and a hot plate to dissolve the acid. 

Kendall and I ended up getting a 3% error so I am pretty pleased with how this lab went. 

Here are some cool pictures we took during the dissolving of the unknown acid. 

Vinegar Acetic Acid Lab

Over the past few days in class we have been completing the Percent Acetic Acid in Vinegar Lab. As the name suggests, we are finding the concentration of Acetic Acid in commercial vinegar.

To do this, we put an NaOh solution in a buret. Then we measured out .5 g of KOH and added it to 75 mL of water with 3 drops of Pheno. We titrated the NaOh into the KOH solution until it turned pink and recorded how much NaOh was used. 

Then we completed the same titration process with the buret and the NaOh but with a solution of 10mL vinegar and 100 mL water, also with 3 drops of indicator. 

After recording how much NaOh was used, we can now use stoich and molar mass to determine the amount of C2H3O2 in commercial vinegar. 

** you can see the solution start to turn pink.

Resources

This post is simply for me to share some of the resources I have found that are helping me this unit!

• https://www.chem.purdue.edu/gchelp/howtosolveit/Equilibrium/Calculating_pHandpOH.htm

• http://www.chemteam.info/AcidBase/AcidBase.html

• http://www.chemteam.info/AcidBase/pH-Strong-Acid-Base.html

• http://www.chemteam.info/AcidBase/Strong-Weak-AcidBase.html

• http://www.sciencegeek.net/Chemistry/taters/Unit8pH.htm

• http://calculator.tutorvista.com/pH-calculator.html

Converting Using the Ph Grid

Using this grid. you can easily see how we convert from H to OH, OH to pOH, pOH to H, and so on!

Don't know why we do all of this? Well, I'll explain.

When converting from pH to pOH you simply use the equation pOH + pH= 14. This is because the pH scale is 14 and the amount of hydroxide ions you have will always be counterbalanced by the amount of hydronium ions to equal 14.

We convert between H and OH with the natural ionization rate of water over the H or OH concentration to find the amount needed.

The H concentration is 10^-pH because moving up or down by an increment of 1 on the pH scale equals 10 times more acidic or basic of a solution. And that is measured by the H/OH concentration.

I hope those explanations helped you remember why we are using these equations!

Vitamin C Lab

So today in class we did the Vitamin C lab! We started out by making a 1.00 mg/ml standard solution of vitamin c by crushing a 500 mg tablet and adding 500 ml of water. We took 20 drops of that and added in 3 drops of startch, our indicator. We added startch into the reaction because when we add iodine, we'll know the reaction is done when the solution turns dark blue. That means there is no more vitamin C solution to react with. Anyways, after the 3 drops of startch we added drops of iodine into the solution until it turned (and stayed) a dark blue. We tested pear nectar, V8, apple juice, and white grapefruit juice. 

In the end, grapefruit juice had the highest vitamin c concentration and pear nectar had the lowest. 

Analysis of Commercial Hydrogen Peroxide

This lab involves combining molarity and stoichiometry to determine the percent of commercial hydrogen peroxide, This is produced when you react peroxide with potassium permanganate.

First we allocated solutions of KMnO4 and H2O2 and measured their masses.

Then, we added 20-25 drops of H2O2 to a test tube, plus 4 drops of sulfuric acid.

Then we added KMnO4 until a faint pink color remained.

Once we did this, we calculated the percent of hydrogen peroxide through stoichiometry and molarity problems.

Molarity Lab

The second lab we are doing this quarter is about a murder mystery! It is kind of a play off on the game Clue, and our job is to figure out what mystery chemical was used to murder Ms. Scarlet.

First we set up double replacement reactions to see which substances had the likelihood of producing a clear liquid (as seen on the scene of the crime).

Then, we went back in lab and ran an experiment with NaCO3 and the mystery substance to see what precipitate it produced. We collected it in filter paper and are waiting for it to dry!

Once we collect the dried substance on Tuesday we can then determine the molarity of the substance and identify the murderer. 

Edit-- the murderer is Mr. Green because the molarity of AgNO3 is .06. 

Quiz

Today in class we took a quiz over the first part of chapter 15 and some review over stoichiometry and limiting reagents. Overall, I thought the quiz was pretty okay (even though that's what I thought for the last 3 tests and we all know how that went).

So far in Chapter 15, we have learned about dilution, molarity, hydrogen bonding, and saturated, unsaturated, and supersaturated solutions. I am really curious to see how these all tie together in the second half of the chapter.

If anyone struggled with the quiz or was looking for more practice for the real test, here are some helpful links I used to study for today's test.

https://app.schoology.com/course/309537052/materials/gp/455085153

http://www.chemteam.info/Solutions/Dilution.html

http://www.chemteam.info/Solutions/Molarity.html

**Overall,, I find the chemteam.info website really helpful.

Dilution lab

Today in class we did a dilution lab! We started with a stock solution containing 20 drops of red food coloring and took equal portions of that stock, added 9 mL of water to each aliquot, and put that new substance in a new cup. We kept doing this until the liquid was clear. 

Overall, this lab was really helpful in learning how to solve real life dilution problems!

Here are some links if you need more help with dilution:

http://www.docbrown.info/page04/4_73calcs14other3.htm
http://chemistry.about.com/od/chemistryquickreview/a/dilutionmath.htm
http://chemistry.about.com/od/chemistryquickreview/a/dilutionmath.htm