10/4/2011 Chemistry

Today in chemistry, first we went to page 399 in the textbook and discussed the states of matter.

Solid: amorphous or crystalline, definite shape and volume

Liquid: no definite shape, definite volume

Gas: no definite shape or volume

Discussed information:

The density of solid materials is usually more dense than the other states of matter, with the exception of water and some other materials. Water expands as it freezes, instead of shrinking in volume like most materials. This is why ice floats. Crystalline solids have molecules that are arranged in a repeating pattern. Most solids are crystalline. Mrs. Sorensen makes an analogy between little kids and the states of matter, in warm weather they run around (like a gas' molecules move quickly with no order), in fall temperatures they kind of huddle up, but still run around a bit (like a liquid's molecules), and in winter they huddle up (like a solid). Crystalline solids sometimes form crystals. We briefly discussed what a unit cell (page 400) was, and then we read about amorphous solids (page 403). We discussed how the myth started that glass is a liquid, but it is actually is an amorphous solid, and how some old textbooks say that it is a liquid. This myth was started by the observation that in old houses, the bottoms of the windows were thicker than the tops. We also discussed that the bigger the crystals, the more imperfections that they have and the less clear they are. Mrs. Sorensen also has two bouncy balls, one that is a "happy" ball and one that is a "sad" ball. They look exactly the same, but the "sad" ball is an amorphous solid and the "happy" ball is a crystalline solid, and the "happy" ball bounces and the "sad" ball does not.

(page 397) We also discussed viscosity, which is a measure of the resistance of a liquid to flow. Mrs. Sorensen also "raced" marbles inside of graduated cylinders with different liquids inside. Two of the liquids did not allow the marble to quickly move down, and they went very slowly. One of the liquids had a dent in the surface because of the marble impact. Seth dropped his marble too quickly and we had to retest between him and Brandon, with the result that Brandon's was found to be faster. Dustin's marble was in 3rd place, and Carson's marble was last. The fastest liquid was water, the second fastest was bubble water, the third fastest was corn syrup and the least fast was Germ-X.

Later, we started to make oobleck and flubber.

Oobleck:

Dixie cup + water + corn starch + stir

Flubber:

Person 1:

30mL water + 2 scoop spatulas of borax + heat (be careful) + stir while being heated

Person 2:

60mL glue NOT IN GRADUATED CYLINDER (measure 60mL water, put in a Dixie cup, mark level with sharpie, empty cup, fill with glue up to mark) + 30mL water + food coloring + stir