做一次喷了六次水

做一次喷了六次水

Tuesday, May 18, 2010

MiniProject #3: Ice Cream

做一次喷了六次水We made ice cream today in chemistry class. I think this was the best thing we've ever done in this class, except maybe the glass bending. I only remember doing this once in fifth grade. It brings back memories of my childhood and happiness. How wonderful.

Materials
  • Ice
  • Milk
  • Sugar
  • Plastic Bags
  • Salt
  • Vanilla Extract

Instructions
1. Mix ingredients for ice cream in one bag.
2. Mix salt and ice in other bag.
3. Put ice cream bag into salt and ice bag.
4. Shake until ice cream forms.
5. Take out ice cream.

Caution: If lactose intolerant or diabetic, do not consume. Make sure ice cream is not contaminated by salt.

Links that explain what to do.Very well.

This involves thermodynamics. The salt lowers the freezing temperature of the ice. Apparently, using rock salt doesn't lower it as much as table salt (surface area, no doubt), allowing it to freeze slower and smoother. The ice starts melting and the heat is transferred from ingredients to icy water.

Photo Credit: Suleiman Jweinat

I eat ice cream

Saturday, May 15, 2010

MiniProject #2: Denatured Proteins

I made some playdoh by denaturing proteins. I wonder if that's how commercial playdoh is made normally. Either way, this lesson was very helpful in demonstrating the properties of proteins.

The ingredients we used were:
  • cup powdered tempera
  • salt
  • water
  • oil
  • food coloring
  • flour
We basically just mixed them together and stirred them in a pot that was heated on a hot plate.
It was easy. The mixture solidified and we could play with it.
Caution: Hot things are dangerous. Do not touch them. Playdoh is nasty tasting (though not poisonous), do not eat.

I liked this lab because it was easy and fun. All we had to do to make the playdoh was mix the ingredients and heat it up. Then we had the rest of the period to play with the playdoh. I think I made quite a large chunk of playdoh. I didn't keep it though.
This is a picture of my project (Photographic Credit: Suleiman Jweinat)
The final result of the project.

!WARNING! Science Ahead
Proteins are made up of amino acids. When protein is denatured, the secondary and tertiary bonds can be broken or disrupted, but not the main peptide bonds. Examples of bonds that can be broken or disrupted are hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic interactions. Therefore the amino acid sequence, or the primary structure, remains unchanged.
In our experiment, we broke the bonds with heat, but they can also be broken with alcohol, acids, bases, or heavy metals.
Learn more

Thursday, May 6, 2010

My Standards Post: Le Chatelier's Principle

Standard 9a.Students know how to use Le Chatelier's principle to predict the effect of changes in concentration, temperature, and pressure.
LeChatelier's principle predicts what will happen when a reaction at equilibrium is affected.
It shows how the changes in pressure, temperature, and concentration affect the rate of the reaction. A simplification of how Le Chatelier's principle works is that the shifts the reaction towards the side that will reduce the change.
Examples
1.
Fe3+(aq) + SCN-(aq)
(colourless)

FeSCN2+(aq)
(red)
For this reaction, increasing the concentration of Fe3 or SCN will shift the reaction rate towards the right to use up more of the Fe3 or SCN.
2.
2NO2(g)
(red-brown)

N2O4(g)
(colourless)
For this reaction, increasing the pressure would shift the reaction rate towards the side that has the least number of gas particles. There are two particles on the left and one on the right, therefore the reaction rate would move towards the right.
3.
Ag+(aq) + Cl-(aq)
(colourless)

AgCl(s)
(white)
+ 112 kJ



For this reaction, heat is being released. If the heat is increased, then the reaction will shift towards the right.
Here are some more examples.

Le Chatelier's principle has many practical uses in manufacturing. The principle is used to speed up the rate that the chemicals are manufactured. This makes it practical or profitable for a variety of chemicals to be made.

This is Henri Le ChatelierThis is also Le Chatelier

Field Trip or Let's Walk Around in Circles


View Mills Canyon in a larger map
I really didn't like the field trip. We walked up a hill to go see a long loop in a forest. We couldn't see anything besides the trees next to us, the spiky plants, and the poison oak. We walked around in the mud and looked at trees while longing for sunlight. There was supposedly a creek, but I think it was just a drainage ditch. Once we went around in a loop once, we still couldn't leave and we were told to "explore." I ended up sitting in a tree, bored out of my mind. Sid and I started playing with trash around the "park." We found cable wire and beer bottles next to a house. Basically, we were all bored and playing in an environment unsuitable for children. Mr. Olson even left during our fieldtrip.

Monday, April 26, 2010

Miniproject #1: Bending Glass

As I mentioned before, we had a series of days in which we melted glass with bunsen burners and shaped them however we wished. The things we used included:
  1. glass tubes with lower melting points
  2. files
  3. Bunsen burners
We basically just used the files to make a small cut and then break the tubes. We turned on the Bunsen burners and held the tubes in the flame until they melted.
Caution: Fire is dangerous. Hot things are dangerous. Do not touch them. Glass shards are dangerous. Do not stick them in your eye.

This lab was the best out of all the others that we have done. My only regret is that it seems to have ended right after I got the hang of melting the glass (I'm a slow learner). Its actually very easy to melt and fuse glass once you get it into the right spot in the flame. I accidentally bumped into Suleiman's project and now we have a joint project (Pun intended).
This is a picture of my project (Photographic Credit: Suleiman Jweinat)
The fruition of my wonderful artistic abilities
!WARNING! Science Ahead
Glass usually contains silica. It is an amorphous solid, basically meaning that its molecules don't have a repeating pattern in all three dimensions like crystals. It has many uses including: optics (lenses), building material, containers, etc. Like all materials, melting it causes the molecules to move around more allowing glass to be shaped. That is what happened.
Simple English Wikipedia is wonderful.

Friday, April 23, 2010

Glassbending

We heated up glass and bent it. We used Bunsen burners to heat up the glass. The glass was also a special glass with a lower melting temperature. We made lots of cool designs.
Here's some glass melting.

I'll be making a mini project post about this later. It will discuss my experience bending glass more indepth.

Friday, April 16, 2010

IProposeWeMakeIceCream


Materials
  • Ice
  • Milk
  • Sugar
  • Plastic Bags
  • Salt
  • Vanilla Extract

Instructions
1. Mix ingredients for ice cream in one bag.
2. Mix salt and ice in other bag.
3. Put ice cream bag into salt and ice bag.
4. Shake until ice cream forms.
5. Take out ice cream.

Safety Precautions
If lactose intolerant or diabetic, do not consume. Make sure ice cream is not contaminated by salt.

Links that explain what to do.Very well.

This involves thermodynamics because the salt lowers the freezing point of ice but makes it colder.