Tuesday, September 14

Today we started class with checking our answers for the 1.2 measurements reading sheet (packet pages 19&20). Next, we went over and completed problems 13, 14, 15, and 17 in our unit packets on page 7. These problems were measurements of volume which consists of cubic meters/centimeters, milliliters and liters. We were introduced to a new theory stating that 1 cm cubed=1 mL. That piece of information was key to solving these four problems.

This is my work for the problems above:

After going over and completing those problems on page 7, we were introduced to scientific notation. This can be located on packet page #8. Scientific notation, aslo known as exponential notation, is a way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation. On this packet page we converted numbers from standard decimal notation to scientific notation, and then we converted from scientific notation to standard decimal notation. When converting you need to keep in mind that the rule of significant figures still applies. A helpful website for understanding scientific notation is:

http://en.wikipedia.org/wiki/Scientific_notation

When converting, you always write the notation with the FIRST NONZERO NUMBER. (decimal) REST OF SIGNIFICANT FIGURES FOLLOWING *(times) 10 to the Xth power. To determine the exponent (x), you count how many spaces you have to move the decimal (right or left) in order to reach that first nonzero number. If the exponent is positive, that means there is a larger number with numerous zeros after it and you will be moving the decimal point to the left. If the exponent is negative, it would be a very small number and you have to move the decimal point to the right.

If you are trying to convert the numbers from scientific notation to the standard decimal notation, you have to move the decimal place and then fill in zeros. If there is a negative exponent, you will move the decimal point to the left ____ spaces. If there is a positive exponent, you will move the decimal point to the right ___ spaces. Like I said before, significant figures are still in effect for these problems.The last section (3) on page 8 in the unit packet is practice using scientific notation on a calculator. When entering the operations on the calculater, you have to make sure to include all parentheses in order for the answer to come out correct. There is a special "EE" button on the CAS calculators especially for scientific notation. After getting an answer on the calculator, you were then to put those answers back into scientific notation, but more simplified than the original.

The last thing we talked about in class was chemical and physical properties. A chemical property is a property of a substance which describes how the substance interacts (reacts) with another substance. A physical property is a property of a substance which describes the substance without describing its interaction with other substances. This was followed up by a demo lab where Mr. Henderson heated a colorless test tube over a methane burner. The test tube then turned a purplish color and took solid iodine and changed it to a gaseous iodine. This was used during the process of sublimation which includes freezing, melting, boiling, etc.

Here is a link to an interactive website to help you understand the difference between chemical and physical properties:

http://www.teacherbridge.org/public/bhs/teachers/Dana/chemphys.html

Monday, September 13

We started class today with Mr. Henderson telling us to get out our calculators, lab notebooks, packet, and to make sure we had patience. We began class by reviewing Lab MM6, the Conservation of Mass Lab. During this lab, we measured the mass of chemicals before and after a chemical reaction. The purpose was to figure out if mass was retained or changed during a chemical change. One person from each lab group went to the front of the room to record their data so we could see what the overall data of the entire class was. This is what the class data turned out be:

We then discussed whether or not the results of the lab shows that mass is retained during a chemical change. Some people said that mass was lost, since some of the masses decreased lightly. Others said that the mass stayed the same because it only changed slightly. Mr. Henderson told us that the mass had stayed the same. He said that in chemistry, 157.37=157.21. This could be because of the uncertainty or some of the chemicals may have fallen out when it was measured for the second time.

Once we finished reviewing the lab, we started to learn about metric conversions. We were told we had to memorize four of the prefixes. We learned a great way to remember them.

1 kilometer=1000 meter

100 centimeters= 1 meter

1000 millimeters=1 meter

10^9 (1,000,000,000) nanometers=1 meter

We also learned a way to remember the many different prefixes by using a scale.

We learened how to use this scale to do metric conversions. If you wanted to convert a kilometer to a meter, you move the decimal place 3 places to the right since the base unit is 3 spaces to the right of the kilo. If you wanted to convert millimeters to meters, you move the decimal place 3 places to the left since the base unit is 3 units to the left of the milli. We practiced doing this by doing a worksheet, page 7 in the packet.

We then went over problems 7 and 8 form the worksheet. 7 was converting 1 mL to kL. First we learned to convert it to L. If you move the decimal place 3 to the left, you get 0.001 L. If you move that 3 more places to the left, you get 0.000001 kL. for 8, the problem was to convert 1.0 Mg to mg. Mg was not on the scale, but it was listed on the worksheet as 10^6. If you calculate 1.0 X 10^6, you get 1,000,000 g. It still needs to be put into mg from g, so you move the decimal place 3 spaces to the right. The solution to that is 1,000,000,000 mg (10^9 mg).

We finished class by being assigned our homework to do a Webassign reading sheet for tomorrow and our Delicious Assignment, which is due on Friday. Overall, it was a very productive class.