8/31/09

TEST TOMORROW OVER CHAPTERS 1 & 2!

Answers to problems we went over in class:

6a. 1800 cm^3

6b. .002 m^3

6c. 1.8 x 10^6

Answers I got for the rest of them (I can't guarantee these are correct):

7a. .01 kg/m^3

7b. 1.3 g/mL

7c. 78 kg/dm^3

8a. 130 mm^3

8b. 19 cm^3

8c. 5.0 m

8d. 4000 m ^3

9. 26,000,000 m^3

10a. 13.38 g

10b. 100 mg

10c. .015 L

10d. 315 cm^2

10e. 14.47 kg

10f. 353 mL

8/28/09

Sorry I didn’t put the blog up earlier, it was a crazy weekend. We all know that we have to first of many chemistry tests on Tuesday. To study you need to:

• Know all the vocab of chapter one and two, whether covered or not

• Branches of chemistry

• Matter

• Class of matter

•Intensive/extensive

•Homo and heterogeneous

•Elements (know how they are organized aka metalloids alkaline and alkaline earth metals, the works)

• Types of elements

• Know what a theory is and how to use the scientific method

• Know the SI units on page 35 and their abbreviations

•Significant figures

•Know how to use conversion factors to solve word

Problems

Ex. Shelby swam 30 meters in 30 seconds, calculate her speed in mph.

How and what to study

First read the chapter, I know it’s not the most fun thing to do on a Sunday but read the chapter.

Second, use the “Cliff notes” on page 21, if you don’t understand something go back over it, there’s an index

Work the practice problems at the end of the sections, on your homework, and on page 881. SI problems on page 40.

Study you quizzes!!!

Pray a little bit

ASK QUESTIONS ON MONDAY

If I missed anything text me to tell me because this is what I’m doing

oh and my advice, don't study monday night at ten you will fail and I will laugh at you.

8-27-09

Thursday August 27, 2009
Today in class, we simply just took notes and discussed what we were taking the notes on. Here are the notes from today’s class:

Mathematical Operations Using Scientific Notation
3. Division
The M factors are divided, and the exponent of the denominators is subtracted from that of the numerator.
Ex.
D=M/V = 5.44/8.1 X 10^7-3 g/mol
=0.6716049383 X10^3
=6.7 X10 ^2 g/mol

Using Sample Problems
Analyze
The first step in solving a quantitative word problem is to read the problem carefully at least twice and to analyze the information in it.
Plan
The second step is to develop a plan for solving the problem.
Compute
The third step involves substituting the data and necessary conversion factors into the plan you have developed.
Evaluate
Examine your answer to whether it is reasonable.
1. Check to see that the units are correct.
2. Make an estimate of your expected answer.
3. Check the order of magnitude in your answer.
4. ***Be sure that the answer given for any problem is expressed using the correct number of significant figures.***
Ex.
Calculate the volume of a sample of aluminum that has a mass of 3.057 kg. The density of aluminum is 2.70 g/cm^3.
V= M/D 3.057 kg converts to 3057 grams using conversion factors

V= 3057 g / 2.70 g/cm^3
V= =1132.222……
V=1130cm^3= 1.13 X 10^3 cm^3

Direct Proportions
Two quantities are directly proportional to each other if dividing one by the other gives a constant value.
-read “y is proportional to x”
Inverse Proportions
Two quantities are inversely proportional to each other if their product is constant.
-read “y is proportional to 1 divided by x”

8-26-09

Scientific Notation - in Scientific Notation numbers are written in the form M X 10^n, where the factor M is a number greater than or equal to 1, but less than 10; and ^n is a whole number.
Ex.
0.00012 mm = 1.2 X 10^-4; NOTE, if you move the decimal point to the left it is a positive exponent, if you move the decimal point to the right it is a negative exponent.

"Rules"
1. Determine M by moving the decimal point in the original number to the left or right so that only 1 nonzero digit remains to the left of the decimal point.
2. Determine ^n by counting the number of places that you moved the decimal point; (either to the left or the right.)

Mathematical uses.

1. Addition and Subtraction- operations can be performed only if values have the same exponent.
Ex.
4.2 X 10^4 kg + 7.9 X 10^3 kg = 4.99 X 10^ kg, however it is rounded to 5.0 X 10^4 kg.!
you could also solve this problem by switching to 10^3, however it would cause more work..

2. Multiplication and Division- M factors are multiplied or divided, then the exponents are added together.
Ex.
(5.23 X 10^6 um)(7.1 X 10^-2 um)
= (5.23 X 7.1)(10^6 = 10^-2)
= 37.133 X 10^4 um^2
= 3.7 X 10^5 um^2. <----- final answer!

NOTE, ALL SIGNIFICANT FIGURES' PROPERTIES APPLY TO ADDITION, SUBTRACTION, MULTIPLICATION, AND DIVISION OF SCIENTIFIC NOTATION!

Welcome

Welcome to the CBHS Honor's Chemistry Blog! Tonight you will begin reading this blog and posting or commenting. You will receive credit! You should have an email in your CBHS student email account inviting you to this blog. Your first assignment is to enroll and comment on the blog about today's class.

Dr. B