November 1, 2010

Today is Monday, November 1 (can u believe that it is already November?!?!?!) and we took our quiz and started learning on our new subject: DENSITY !!!! yay !!!

Here is what we did in order:
- First we corrected our review sheet for sig figs.
- Then we took our quiz
(which was on Significent Figures, Uncertainty, Scientific Notation and Measurement)
- And for the remainder of the class we took notes on Density and we got a worksheet for homework.

* Here is a quick lesson on Density:
Facts;
- Density = mass divided by volume
- Volume = mass divided by density
- Mass = density times volume
- Density of a solid = g/cm cubed
                      liquid = g/mL
                      water = 1.0 g/mL or 1000 g/L
- If the density of an object is greater than the density of liquid the object will sink
And if the density of an object is less than the density of liquid the object will float

Examples of Density Problems (see if you can figure them out)
1) Calculate the density in g/mL of aluminum if a 50 mL block weighs135 g.

2) Calculate the mass in a 200 cc block of Titanium with a density of 4.51 g. per cc.

3) Calculate the mass of a liquid with a density of 3.2 g/mL and a volume of 25 mL.

4) An irregular object with a mass of 18 kg displaces 2.5 L of water when placed in a large overflow container. Calculate the density of the object.

5) A graduated cylinder has a mass of 80 g when empty. When 20 mL of water is added, the graduated cylinder has a mass of 100 g. If a stone is added to the graduated cylinder, the water level rises to 45 mL and the total mass is now 156 g. What is the density of the stone?

Since density is known worldwide and can be connected to so many things here are some news articles and papers that you should check out! 
1. http://www.warsawvoice.pl/WVpage/pages/article.php/22750/article
2.http://news.softpedia.com/news/Saturn-s-Rings-Are-Proxies-for-Galaxies-164138.shtml
3. http://www.usnews.com/science/articles/2010/11/01/revealing-the-galaxys-dark-side.html
Here is a website that focuses all on science news and very interesting news:
1. http://insciences.org/articles.php?tag=Chemistry


Images to help with density:

 

A density joke that ought to make you chuckle!
 - In world war 1 a great big british mine found itself sinking through the ocean right next to a great big german mine. After a while the great big british mine said - 'I say, we seem to be sinking at exactly the same rate - we must have the same density!'
'Somehow I doubt zis!' replied the great big german mine; 'It is just zat great mines sink alike...'

And four videos about Density & Volume & Mass!
- http://www.youtube.com/watch?v=fqLCwuKMBMA
- http://www.youtube.com/watch?v=rxb_6UANXqU
- http://www.youtube.com/watch?v=grWG_U4sgS8&feature=related
- http://www.youtube.com/watch?v=uvy4nWh0KwE&feature=related

Last but not least for next class....................
- We are doing Lab 2E. So dont forget to make a chart of the procedures and make a copy of Table 1.
- Finish the density problem worksheet.