I'm disgustingly blunt! lol We really appreciate the time you take to help us with this important information! You are such an

asset!!! You are a natural instructor!

(7:00 tonight OK? LMAO!)

Anytime is good with me BG, but I need a full 24 hours to get ready for you. You know you always run me down, and I need another 24 hours to rest. LOL Anytime BG. Anytime. Thanks for the kind words.

Sorry guys for not having this up sooner, some shit came up. But here is the next installment for you. Best of luck.

Significant Figures.

Because doing chemistry requires many types of calculations, we must consider what happens when we do arithmetic with numbers that contain uncertainties. It is important that we know the degree of uncertainty in the final result. Although we will not discuss the process here, mathematicians have figured out how uncertainty accumulates and have designed a set of rules to determine how many significant figures the result of a calculation should have. In school my chem teacher called them "Sig Figs" and my physics teacher called them "Sig Digs" (as in significant digits.) Doesn't matter. There are rules to counting sig figs and you should follow them whenever you carry out a calculation.

These include.

1. Nonzero integers. Nonzero integers ALWAYS count as significant figures.
ex. 1653 has four Nonzero integers, ALL of which count as sig figs.

2. Zeros. There are 3 types.
a. Leading zeros are zeros that PRECEDE all of the nonzero digits. They NEVER count as sig figs.
ex. 0.0025 the 3 zeros simply indicate the position of the decimal point. The number itself only has 2 sig figs, those are the 2 and the 5.

b. Captive zeros are zeros that fall between nonzero digits. They ALWAYS count as sig figs.
ex. the number 3.0008 has 5 sig figs.

c. Trailing zeros are zeros at the RIGHT END of the number. They are ONLY significant if the number is written with a decimal point.
ex. The number 100 has only 1 sig fig. However the number 100. would have 3 sig figs. The decimal point at the end makes them significant. (Ok there may be some confusion here. If it is a number like 154680 the 0 on the end doesn't count. If it were 154680. then the zero would count as a sig fig. However a number like 0.0005640 the last zero does count. The first 4 don't mean shit. But the one after the 4 does. It does have a decimal point (I know it was way in the front, but there is still a decimal point in there.) hence the reasoning in why it counts. It is as if you weighed out a gram of coke on a nice scale. It would say 1.00. Your scale weighed that bitch right out evenly to 2 places after the decimal, so those 3 numbers are significant. If it weighed it out to 1.01 all three would be significant as well. Here I will make it easy for you. ANYTHING AFTER THE DECIMAL COUNTS, as long as it isn't a preceding zero!!! How does that clear shit up for you???) LMFAO

3. Exact Numbers are often calculations involving numbers that were not obtained using measuring devices but simply by counting.
ex. 10 experiments, 3 apples, 8 molecules. Such numbers are called Exact Numbers. They are assumed to have an infinite number of sig figs. Exact numbers can also arise from definitions.
ex. 1 inch is defined as EXACTLY 2.54 centimeters. Thus in the statement 1in.=2.54cm. neither 2.54 NOR 1 limits the number of sig figs when used in a calculation.


Rules for counting sig figs also apply to numbers written in scientific notation.
ex. The number 100. can also be written as 1.00x10^2, and both versions have 3 sig figs.
Now this is where scientific notation offers two major advantages. The number of sig figs can be represented easily, and fewer zeros are needed to write a very large or very small number.
ex. the number 0.000060 is much easier to write as 6.0x10^-5 and the number has 2 sig figs written in either form.

Practice problems. Just state the number of sig figs in each number.
1. Sample of Orange juice contains 0.0108g of Vit. C
2. A single hair has a mass of 0.0050060g
3. 5.030x10^3 ft
4. In the bicycle race 110 riders started but only 60 finished.
5. 0.00100 m
6. 2.0800x10^2 L
7. 480 Mustangs
8. 1.0000576893000


Rounding

When you do calculations on your calculator you will most likely end up with a number with more digits than the number of sig figs the result allows. So you must round it to fit that need. Here are the rules to rounding.

1. If the digit to be removed
a. is less than 5, the preceding digit remains the same.
ex. 1.33 rounds to 1.3.

b. is equal to or greater than 5, the preceding digit is increased by 1.
ex. 1.36 rounds to 1.4, 4.25 rounds to 4.3

2. In a series of calculations, carry the extra digits through to the final result THEN round off. That means you should carry ALL the digits that are on your calculator until you arrive to the final number (your answer) and then round off. (Basically keep your damn numbers as long as you can, and when you are done with the problem and have your answer then round that bitch to the right amount of sig figs. Don't worry about the other ones, just your answer is rounded. Got it???)

Another thing, Suppose the number 4.348 needs to be rounded to 2 sig figs. In doing this we ONLY look at the FIRST NUMBER to the right of the 3. (In this case, other cases would be the first number to the right of the last sig fig.)
This means that the number will be rounded to 4.3 because 4 is less than 5. It is INCORRECT to round sequentially.
ex. Do NOT round the 4 to 5 (Because of the 8 on the end) to get 4.35 then round the 3 to 4 to get 4.4
That is just plain WRONG. So don't fucking do it. When rounding off use ONLY the first number to the right of the last sig fig.

Problems.
1. 1.0002485 to 3 sig figs
2. 78543 to 4 sig figs
3. 0.0004500032840 to 1 sig figs
4. 890008974000. to 7 sig figs
5. 1.00067854 to 8 sig figs
6. 222 to 1 sig fig
7. 897465.000173 to 9 sig figs
8. 756348 to 3 sig figs.

You are SUCH a great teacher!!! Where were YOU when I first tried to learn math, Satan, my love? HMMMMM?

(and if anyone says, "He wasn't even born yet, BG," I'm gonna !!)

gotta start reading this, planning on taking a chem class next year, bought an old chem book from the library for a dollar. chemistry can def. come in handy, gonna try and make anhydrous acetone with epsom salt(not sure if this even works, which is were chemistry would play a big role)

That would be organic chem. First off how pure is the acetone you have??? Secondly once it is made, it will suck water right out of the air so you have to use it quickly and properly. Are you sure you need it to be anhydrous???