All About Phases

Today in chemistry class we started out by learning about phase diagrams. They are representations of the state of substances based on the temperature and pressure conditions. The pressure is listed on the y-axis( in mmHg) and the temperature on the x-axis (in degrees celsius). The points on the graph indicate that states are in equilibrium. Point A, the triple point, is a point where all three states are in equilibrium. If a substance is gotten to exactly the right temperature and pressure of its triple point, all three states will be present.

We learned that the state of a substance can be manipulated by using pressure. For example, a tank of propane gas used for grilling is kept at high pressure in order for it to remain in liquid state in the tank before it is needed. However, when the valve is open to get the propane gas to the grill, the pressure is lessened and the propane needed is changed to gas form.

Mr. Lieberman did a demo where he simulated boiling by putting dry ice in a beaker of water. He said that once the pressure in the gas bubbles equals the pressure in the water, vapor will be formed.

Mr. Lieberman also did a demo that proved that pressure affects the state of water and any other pure substance. He put a beaker of water inside a vacuum and started lowering the pressure. The water started boiling within 30 seconds and produced vapor.

Lastly, Mr. Lieberman showed us dry ice in all three states by putting some in a tube and sealing all the holes. He then held this tube into a beaker of water and we watched the dry ice turn into liquid form from its solid state. Also, we saw vapor bubbles frequently during many attempts at perfecting this demo. These vapor bubbles indicated the presence of a hole in the seal of the tube. Finally we saw dry ice in liquid form!

This has been Korri H!!

The next scribe is Katie I.

Don't forget to do the worksheet!

Hydrate Lab Day!

We started class with finishing the back sides of our quizzes for 10 minutes. Then we started the pre-lab for the Hydrate Lab we did in class. We first discussed three rules to follow when operating a Bunsen Burner. The first rule is to not leave it on unattended, do not touch it while hot, and keep all hair tied back and loose sleeves out of the way. The next question we discussed was to find:

a. The mass of the hydrate

b.the mass of the water lost during heating

c. the percent water in the hydrate

We were given the mass of:

Empty Test Tube: 18.42 grams

Test Tube and Hydrate (before heating): 20.75 grams

Test Tube and Anhydrous Salt (after heating): 20.41 grams

To calculate these you had to:

a. 20.75 g -18.42 g= 2.33 g

b. 20.75g- 20.41 g =.34g

c. .34g/2.33g=14.59% (round for significant figures)=15%

After this question you had to complete the table given on the Hydrate Lab sheet.After this, we got together with our lab groups and began the Hydrate Lab here are the steps:

1. We took the mass of the pyrex test tube.
2. We added around 2grams of blue hydrated (with water) copper (II) sulfate.
3. We then massed the test tube with the copper (II) sulfate in it.
4. We then set up the clamp and tilted the tube slightly down so the evaporating water can leave the test tube.
5. Then then focused the heat from the Bunsen burner on the copper (II) sulfate and heated it evenly until it turned white. We tried to avoid burning it. (turned brown if burned)
6. Then we wiped out the excess water droplets and massed the tube with the anhydrous salt.

So that was our Hydrate Lab! The next scribe is... Ellen Hirsch!!

This was Korri Hershenhouse! Don't forget to do your How Much Are You Worth Project for monday! Also don't forget to complete the webassign and do the post lab also for monday!

The Homecoming Genie

1. Today in our chemistry class, Mr. Lieberman introduced us to the Homecoming Genie. The genie only comes out of its silver bottle once a year around homecoming! He got the genie from his high school chemistry teacher so its an old tradition. He told us that the Homecoming Genie would only come out if we had enough homecoming spirit. Even after he called the genie it still wouldn't come out, so we didn't have enough spirit yet! Hopefully it'll come out tomorrow if we all wear green and silver! After we experienced the homecoming genie, Mr. Lieberman started discussing the alchemy notes (as seen in the above post) with us. He discussed how the alchemists laid the basis for the foundation of chemistry today. They tried to do experiements like turn metals into gold and make immortality potions. Even though these experiments failed (obviously) for the alchemists, the did contribute greatly to science. They discovered:

• elements such as mercury and sulfur


• developed new glassware


• developed new lab procedures (wearing safety goggles)

We learned about the atomic theory:

• Law of Conservation of Mass: Mass is neither created nor destroyed during chemical reactions


• Law of Definite Proportions: a given chemical compound always contains the same elements in a specific proportion by weight.


• Law of Multiple Proportions: when two elements combine to form one or more compounds the weight of one element combined with the fixed weight of the other element are in a ratio of small whole numbers

We learned specifically about a few important early alchemists:

Robert Boyle : developed theories about elements- an element is a pure substance that cannot be broken down into other substances

John Dalton: built on the atomic theory-

• elements consisted of tiny particles called atoms


• elements were pure because all atoms in one element were identical and had the same mass


• elements differed because their atoms had different masses


• compounds consisted of the atoms of different elements combining together


• Atoms:small,indivisible, indestructible particles that had their mass, behavior and size based on what element they are

J.J. Thompson: made the cathode ray: tube with a small amount of gas inside (lead to television)

• he discovered electrons when he used a magnet to attract/repel the electricity inside the ray


• came up with the Plum-Pudding Model:

  

So.. that's what we did on September 27th in Mr. Lieberman's Honors Chem class.. Don't forget your green and silver tomorrow so we can see the Homecoming Genie!! ~Korri Hershenhouse

PS. The next scribe will be Ellen H!!