Mini-Project #3: Making Playdough

Sugars and Polysacharrides!
Components of Starch and other Saccharides

Materials:
- 2 Cups Flour
- 2 Cups Water
- 1 Cup Salt
- 2 Tablespoons Vegetable Oil
- Food coloring!

Procedure:
1. Mix all of the ingredients together, and stir over low heat.
2. When the dough pulls away from the sides and clumps in the center, remove the pan from heat and allow the dough to cool enough to handle.
3. Turn the dough out onto a clean counter or silicon mat, and knead vigorously until it becomes silky-smooth.
4. When you're done store it in an air-tight container.
5. If it begins to dry out, you can knead a bit of water in again to soften the dough back to usability.

Safety Precautions:
- Do not burn yourself on the hot pot.
- It is safe to eat this, but the taste will be unfavorable.

Scientific Principles:
1. Playdough is made out of starch, which is a polysaccharide.
2. Polymers are long molecules consisting of repeating structural units.

Mini Project #2: Rock Candy

In chemistry class, we made rock candy, also known as crystallized sucrose.

Materials:

Popsicle Stick

String

Lifesaver (to weigh the string down)

Glass Beaker

Pot with Saturated Sugar Water (1 cup water, 3 cups sucrose)

Instructions:

1. Tie your lifesaver onto a string, which should be the length of the glass beaker you are using.
2. The tie the string (and attached lifesaver) to a popsicle stick and place into the glass beaker. The string should hang about 1/2 - 1 inch off the bottom of the beaker and should be placed strategically in the middle, so it avoids touching the sides.



3. Boil a pot full of saturated sugar water.
4. Pour the hot solution into the the glass beaker.
5. Place the beaker in a place where it will be undisturbed. Crystals will form when the liquid cools down after a few days to a week.

* Crystals will not form on nylon string.




Safety Procedures

Use hot mitts to handle the pot full of boiling hot water!

Wear your goggles in case hot water splashes into your eye!

Do not use a wishing weight or anything metal to weigh down your string. This could be potentially toxic if you're going to eat your rock candy.

Scientific Principles
1. Crystallization:
Crystals are formed when a substance arranges itself in repetitive arrays. The supersaturated sugar solution contains more sugar than water. As the solution cools over days, the sugar forms as a precipitate on the string.

2. Evaporation:
Over time, the water molecules from the supersaturated sugar solution leaves the rock candy. The crystals thus grow molecule by molecule.

PHOTOCREDIT TO FIONA CHAN AND MARCIA LEE!

Chemistry Standard: Calorimetry

Chemical Thermodynamics
Students know how to solve problems involving heat flow and temperature changes, using known values of specific heat and latent heat of phase change.

Also known as...
CALORIMETRY

You can use a calorimeter to measure the heat quantity of a substance.


Or it can be defined with the infamous equation:
Q = MC∆T
M = Mass
C = Specific Heat Capacity
∆T = Change in Heat Temperature (Final temperature - initial temperature)

A useful constant for C would be the specific heat of water which is 1 cal/grams°C or 4.184 J/grams°C. Ice's specific heat capacity is .5 cal / grams°C and steam's specific heat capacity is 0.4 cal / grams°C.


Water, ice, and steam!

I will demonstrate how to solve for each of the variables (mass, specific heat capacity, and ∆T) in the following video. The step-by-step instructions are supplemented below.

Solving for Q:

A 21.0g sample of water is cooled from 34.0°C to 28.0°C. How many Joules of heat were removed from the water?



In order for calculate the values of ∆T, C, or M, you must use algebra to solve the equation for each of the variables.

I have solved the equations already!

M = Q / C∆T
∆T = Q / MC
C = Q /M∆T

Phase change problems (such as melting from a solid to a liquid) can be solved by using the same formula but by also using the extra formulas:

Q = ∆HVap = 540 cal
Q = ∆HFus = 80 cal

Trips to Mills Canyon

View Mills Canyon in a larger map

I did not embark on this wonderful, positively invigorating trip to view the best-kept secret of Burlingame, also known as MILLS CANYON! I was not too upset at missing at missing this opportunity, though. I see nature in its finest form quite often, actually, because 1) my cousin has a house in the wilderness of Santa Rosa and 2) I've walked on wild trails before. Therefore, going to Mills Canyon would have not been a new experience.

Mini-Project #1: Make Invisible Ink

How to Make Invisible Ink
Chemical Properties of Lemon Juice


Materials:

Half a lemon

Water

Spoon

Bowl

Cotton Bud (Swab, Ball)

White Paper

Lamp or other light bulb

Procedure:

1. Squeeze some lemon juice into the bowl and add a few drops of water.
2. Mix the water and lemon juice with the spoon.
3. Dip the cotton bud into the mixture and write a message onto the white paper.
4. Wait for the juice to dry so it becomes completely invisible.
5. When you are ready to read your secret message, heat the paper by holding it close to a light bulb.

Safety Precautions:

Safety first, goggles on!
The acid from the lemon can burn your eyes.

Scientific Principles:
Since lemon juice is acidic and also organic, an oxidation reaction occurs when heat is applied and the words will turn brown. Any other acidic substances will work as well. Catherine and I used vinegar as a substitute.





PHOTOCREDIT: Marcia Lee

The project itself failed slightly, as we did not have a lightbulb to hold the paper to, so we attempted sticking it close to the fire. The vinegar began to oxidize slightly, but we did not dare sticking the paper any closer to the fire. By the way, the message reads "HI! WE LOVE CHEM!"

IProposeWe: Make Fireballs that are Cool Enough to Touch!

Links:
How to Make a Fireball
Step-by-Step Video Tutorial



Materials:

2" x 5" strip of cotton cloth

A cotton threaded needle

Lighter fluid (must be naphtha or kerosene)

Lighter or matches

There are two procedures to this experiment. First, the creation of the ball itself...

Procedure:
1. Thread the needle.
2. Fold the cotton strip into a ball and pierce it with the needle.
3. Wrap the thread around the ball. Pierce the ball one more time and break the thread.

And of the fireball:
1. Place the ball on a fire proof surface, such as a pan or our chemistry tables.
2. Soak the ball with lighter fluid, being careful to avoid hands or clothing.
3. Pick up the ball with tongs before putting it in your hand (to check if the ball is indeed too hot to touch, but it shouldn't).
4. Hold the ball while rotating it in your hand to avoid burning.
5. Put out the fireball when the cotton starts to become black and burn.
6. To blow out the fire, you need to blow on it hard or suppress the fire (by putting the lid on the frying pan, for example).

Safety Precautions:

Avoid synthetic material such as nylon. These will burn and melt.

Avoid holding the ball when the fire begins to consume the cotton or it will be too hot to hold.

Scientific Principles:
1. This is a reaction of combustion, meaning oxygen is a reactant (the air) and carbon dioxide and water are products.
2. This is an exothermic reaction. Energy, in the form of heat, is being released.

STP and Star Review (#12)

STP is not sexually transmitted pleasure.
In fact, it is the standard conditions for temperature and pressure. These conditions happen to be 0 degrees celsius (or 273 K) and 1 atm. 1 mol of any gas at STP has a volume of 22.4 Liters.

By the way, all gas temperatures must be in K (Kelvin).

0 K is absolute zero. You can't go any lower on the temperature scale. Absolute zero is centigrade is -273 C. (C = K - 273)

On a random note, Gay-Lussac discovered the law that as air pressure increases, so does temperature. Yesterday, we tried to find the molar mass of air. I guessed 29.92 g/mol. It actually came out to be approximately 30 g/mol. We figured this out by creating a vacuum in a test tube, measuring the mass of the vacuumed (evacuated) testtube and then when it was released.

I'll update this later!

Today's Guest Visitor

Today, in class, we had a great presentation by David Webb, a member of the American Vacuum Society. Wow, I had no idea such a society existed dedicated to researching the laws of physics, especially vacuums, where there is no sound. We performed a variety of experiments to further instigate our knowledge of vacuums. The first experiment we did is to figure out how much atmospheric pressure is applied to us at all times. Apparently, atmospheric pressure (at sea level) is 14.7 PSI. Whoo hoo. We held a heavy metal bar called the "Earth Bar" to show just how much pressure is being applied to us at all times.

We also used a pressure machine. Basically, it sucked all of the atmospheric air out of a canister. When you put a tied balloon in there, it got bigger. The same thing happened with marshmellows (but after withdrawing the marshmellows, they became shriveled up). Another interesting experiment proved that lack of air, or a vacuum, did not carry sounds. We put a dinging doorbell into the pressure machine, sucked out the air, and voila - the ringing stopped!

By the way, I found this column on vacuums quite interesting. I'm assuming you would probably feel the same. I also learned that something sticks to something, for example a suction cup on a shower glass door, works because of the atmospheric pressure pressing against the cup and creating a vacuum. The force of a vacuum is really strong. When you suck the air of something, it becomes very hard to open it.

Fun Fact: Toricelli, inventor of the mercury barometer, was one of the first inventors who sustained a vacuum.


The machine used looked something like pictured above, just simpler.

Gases and Back from Japantown!

On Monday, we started a new unit about gases. Gas molecules are always moving around; their molecules are the most spaced out apart (compared to liquid and solid). They have "kinetic" energy that goes up when temperature and speed go up. Gas pressure can be measured in a variety of units - mm/Hg, in/Hg, Torr, kPa, and atm. Gases are determined by pressure, volume, temperature, and number of particles. The combination gas law is P1V1 / T1 = P2V2 / T2.
It is a combination of Boyle's Law, Gay-Lussac's law, and Charles's Law.


Near absolute zero, a gas acts as a solid. Absolute zero for gases is 0 K or -273 degrees Celsius. However, temperatures for gases should be measured in Kelvin. There are also a variety of formulas to calculate the volume, pressure, or temperature of a gas. The following formulas, include ideal gas law, kinetic energy laws, and more.


Contrary to popular belief, there is no air in balloons that float. Instead, there is helium.


Ah, it feels so weird to be back from school after a long day of doing nothing...aka going to Japantown with my best friends from Japanese class. Yay! At Japantown, we went on a scavenger hunt about Japanese culture with an assigned group (Emily, Kristel, Elaiza, Rochelle, KT, Charles, and Bruce) Afterwards, we ate at Sapporo Ya. I had chicken teriyaki and ramen and tempura. And coke. MMMMM, yum. Most of my group were freshmen, who were eager to learn about Japanese culture and speak better 日本語。Nooo, I don't want to learn. xD LOL, some people ditched 7th I think. I'm not that bad. I'm eager to learn about chemistry!

MC Delta T

That's calorimetry dogg.
Calorimetry is the measurement of specific heat capacity.
Specific Heat Capacity is the amount of energy required to raise the temperature of 1 gram of a substance by 1 degrees celsius.
The specific heat capacity of water is 1 calorie per grams degree celsius.
and 1 cal is equivalent to 4.184 Joules.
Temperature and heat flow can be understood as the movement of molecules.

Whew, that was confusing.
By the way, calories are different from Calories. 1 Calorie is 1000 calories (cal).


These are some calorimetry problems (with their solutions) that we worked on.

Hmm, what else...?
During phase changes, energy is not required.
See how the line is straight in the following graph?

Homegoing! and Equilibrium

3/26/10

What is equilibrium? Basically, the forward rate of an equation is equal to the reverse rate. Equilibrium resists change. Molecules also need to overcome activation energy in order to start a reaction. Activation energy is the minimum amount of energy needed (in the collision) for a reaction to occur. Molecules react by colliding with sufficient energy and with proper orientation. Catalysts speed up chemical reaction, but they aren't consumed and don't mess up with equilibrium.



2/19/10

Today was the Homegoing Rally. :D Instead of electing princes and princesses, we elected teachers as the Homegoing King and Queen. Mr. Williams and Ms. Dove won! LOL. I voted for Mr. Williams and Mr. Olson. XDD

The Academy of Villains performed for us at the rally today. Compared to what I've seen, they were outstanding. Some of the guys did backflips and frontflips...and just amazing breakdancing moves. I don't even know how to describe them. But they were on America's Best Dance Crew. :D and they're going on America's Got Talent soon! LOL, since Krystina and I were sitting on the floor, they were hecka close to us. O_O We got a pretty good view. During the rest of the rally, our view was obstructed by some people's fatty legs. XD

The teacher's dancing was pretty funny too. That little kid was really cute! Who was he anyway? And the singers of the National Anthem were pretty creative and nice sounding as well!

MONDAY'S A HOLIDAY! <3333 AMERICA!
got to go, bell rang.

Decomposition and Balancing Equations

I really hope we do the elephant toothpaste experiment in class! According to this website about the uses of hydrogen peroxide, elephant toothpaste can be made by decomposing (with the help of catalyst)...well, hydrogen peroxide!


A viscous liquid with strong oxidizing properties!

Hydrogen peroxide decomposes into oxygen and water. The oxygen rapidly tries to escape the container, thus provoking the fast explosive reaction of elephant toothpaste. The soap that was mixed in with the water in the experiment begins to foam. The oxygen further promotes the bubbles to foam.

And ta-da! Elephant toothpaste.

Food coloring adds to the mystery!

On a lighter note...balancing equations is also something I enjoy!
This is a great guide for helping.

For example,
2NaCL + H2So4 -> Na2So4 + 2HCl
That's balanced! Before it looked like:
NaCl + H2So4 -> Na2SO4 + HCl
That's not balanced. x_X See?

Chemistry Lab: Predicting the Formula of a Precipitate

So, my friend, what IS a precipitate?
The answer? An insoluble solid coming out of a solution.



In this lab we performed, double replacement reactions occurred. Reaction 1: Silver nitrate and sodium chloride form silver chloride and sodium nitrate. In the other reaction, silver nitrate and sodium acetate formed silver acetate and sodium nitrate. (Remember, metals replace metals!) A precipitate formed in reaction 1, but not in reaction 2. In reaction 1, AgCl (silver chloride) was the precipitate.

Silver Chloride:

Has a very low solubility in water!

PAUSE: Someone keeps playing the ukulele. -_-; It's kind of annoying, but they play well. lol.

Anyway, in single replacement reactions, metals can be arranged in order of how reactive they are. Metals high in the reactivity series usually displace metals lower down.

REACTIONS!

There are five types of reactions:
1. Synthesis: two elements combining into a compound
2. Decomposition: a compound being separated into elements
3. Single Replacement: metal/H switches with metal/H or halogen switches with halogen
4. Double Replacement: the cations swap anions; sometimes a precipitate is formed.
5. Combustion: CxHy + O2 -> CO2 + H2O + Heat.
Basically, heat is always a product.

(Sorry, Mr. Olson, I plagiarized your reactions worksheet).

Speaking of combustion, the idea of spontaneous combustion fascinates me. Apparently, Robert Francis Bailey was a homeless man who suddenly - well, spontaneously combusted. And thus, he died in the flames.

So I guess the spontaneous reaction combustion that affected poor Mr. Bailey was an exothermic reaction. x___X

Other reactions include oxidation and reduction reactions. In oxidation, electrons are stolen by the electron-hungry Oxygen. In a reduction reaction, electrons are gained. Any reaction where electrons are transferred is called a redox reaction.

Stoichiometry!

The definition of stoichiometry is the relation between the quantities of substances that take part in a reaction or form a compound.



To calculate...

Basically, given gX x (mol X/g of X) x (mol Y/ mol X) x (g Y/mol Y)= g Y.

Moles, or Avogadro's Number, are a key component in stoichiometry. Also, balancing the equation when writing it, is essential. This is how you balance an equation: click here!

To solve, first of all you write the units. And you simply have to write the given! (Do you write the given?). And then cancel your units.

It seems complicated, but after completing a few practice equations, I eventually mastered the art.

Red to Blue, BASE-A-ROO!

Today was Career Day! Lisa, Catherine, Krystina, Marcia, and I all went to the military presentation. Now we want to go and enlist in the army. :D We all looked like sissy girls surrounded by a mob of tough looking dudes and girls that also looked like guys (besides us). We also went to the physical therapist which is Mr. Olson's wife. Actually, we started in the auditorium watching the actor/beatboxer/breakdancer/painter. I wish I was as cool as that and had many talents. I hate rain. D: I have to walk home in the pouring, freezing rain. I already was sick last week, so hopefully, I won't get sick again. -_- By the way, Krystina just reminded me that winter formal is upcoming. Krystina hopes to get my cousin to buy her a $400 dress, including shipping (from Asia) and tax. Then we were prance around Winter Formal looking like the happy children that we are! Haha, I'm confused. -_- Steve LAIIIII, haha, I doubt you'll even read this.

We're "learning" about acids and bases in chemistry. The pH scale (potential of hydrogen) ranges from 0 (acidic, high H+) to neutral (same amount of H+ and OH-) to 14 (basic, high OH-). Strong acids completely dissociate. Acids are proton donors; bases are proton acceptors. Also, we're using logarithms in chemistry. pH = -log[H+]. That is how you determine the concentration of hydrogen ions in a solution. Click here for a useful link about a pH challenge. To determine whether a substance is acidic or basic, you can stick litmus paper in it. Bases turn red litmus paper blue and acids turn blue litmus paper red. Blue to red = AC-ID! Red to blue = BASE-A-ROO! Acids are sour and bases are bitter.



Hydrochloric acid, a very strong acid. Also present in the stomach.

#2 Post of Spring Semester!

Haha, when I logged on, my desktop was full of icons. LOL someone was bored...I had to delete them all. All 200 of them. o_o Ugh, I had a crazy week last week. o_o I don't feel like talking about it. bwaha. Okay, I shouldn't have mentioned it then. -__- Sorry, I had a long day.

Anyway, we're currently learning about solutions. In a lab that we conducted last week, we mixed solutions by dissolving a solid (cobalt chloride).
The expected absorbency was .24 and my group's mixture absorbed exactly that! We also made a solution by diluting a concentrated solution (potassium permanganate). The expected absorbency was this .18 and our groups was .17. :D Nice! By the way, we had to calculate to solve these labs. We used equations to determine variables such as molarity, volume, and moles of solute. Molarity = moles of solute divided by liter of solution. We also used labs to conduct the properties of solutions such as solubility, density, and how freezing temperatures of solutions vary. For example, ice water with salt has a lower freezing temperature than pure water itself. When pressure is high, gas is more soluble.

Like Dissolves Like

Dissolving is process by which a solid or liquid forms a homogeneous mixture with a solvent. When the solvent and the solute mix together, they form a solution. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules. Like substances dissolve other like substances, depending on their chemical polarity.

1. Polar compounds can dissolve other polar compounds and ionic compounds.
For example, water (polar) can dissolve NaCL/Salt (ionic).
Salt before being completely dissolved:

and after...


2. Non-polar compound can only dissolve non-polar compounds.
If you try to mix water (polar) and oil (non-polar), the two won't form a solution.

But oil will dissolve other types of oil, since they are both nonpolar.