Curtis Washington

Mr.Olson showed us his new video describing the characteristics of moles in his video "molesong with curtis"

HOW I CONVERT

Today, we rewatched the "how I convert" video" to refresh our minds about cancellations and units.

Salt Lab

Today we did a salt lab trying to make salt evaporate from a pan of water. We filled the pan about half way with water and dumped a half a cup full of salt inside. Using a stick, we stirred the the salt until it thoroughly dissolved into the water. We then left the liquid on the table. When we came back, the salt was all that was left in the pan!

SIGFIG.

The concept of significant figures is often used in connection with rounding. Rounding to n significant figures is a more general-purpose technique than rounding to n decimal places, since it handles numbers of different scales in a uniform way. For example, the population of a city might only be known to the nearest thousand and be stated as 52,000, while the population of a country might only be known to the nearest million and be stated as 52,000,000. The former might be in error by hundreds, and the latter might be in error by hundreds of thousands, but both have two significant figures (5 and 2). This reflects the fact that the significance of the error (its likely size relative to the size of the quantity being measured) is the same in both cases.

A practical calculation that uses any irrational number necessitates rounding the number, and hence the answer, to a finite number of significant figures. Computer representations of floating point numbers typically use a form of rounding to significant figures, but with binary numbers.

The term "significant figures" can also refer to a crude form of error representation based around significant figure rounding; for this use, see Significance arithmetic.

Time to dig out the mole

Think of moles as a "chemist's dozen". Just as 12 eggs is a dozen eggs, 6.02 × 1023 eggs is a mole of eggs. 6.02 × 1023 molecules of oxygen is a mole of oxygen.
The number of grams in a mole is different from substance to substance. If you're like most students, it's this that's confusing you. Picture it this way: a dozen elephants have a different weight than a dozen rabbits- but in each case, you have a dozen animals. Similarly, a mole of oxygen gas has a different weight than a mole of water- but in each case, you have 6.02×1023 molecules.

Why use moles? You often want to know how many molecules you have in a sample of a substance. Counting the molecules individually would be completely impractical. Even if you had a way to see the individual molecules, there are just too many, even in a tiny sample. Moles were defined to solve the problem of counting large numbers of molecules. With moles, you count the number of molecules in the sample by weighing it.

Holy Moley!

A mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly 12 grams of carbon-12 (i.e., 6.023 X 1023). This involves the acceptance of two dictates -- the scale of atomic masses and the magnitude of the gram. Both have been established by international agreement. Formerly, the connotation of "mole" was "gram molecular weight." Current usage tends to apply the term "mole" to an amount containing Avogadro's number of whatever units are being considered. Thus, it is possible to have a mole of atoms, ions, radicals, electrons, or quanta. This usage makes unnecessary such terms as "gram-atom," "gram-formula weight," etc.

its smelly

Today we did a lab on the different smells contained in a bottle. Each bottle was labeled a different letter and we were given a chart to fill out. We also had to decipher if the smell was sweet or sour. Writing down our guesses, we wafted each smell again to make sure. We then went outside for stronger smells. I have to say, those smelled the worst. Some smelled like cotton candy and others smelled like fish. This was an interesting lab as we made connections. I hope we do more labs like this.

Formulas of the first ten straight-chain alkanes

name: condensed formula:
methane CH4
ethane C2H6
propane C3H8
n-butane C4H10
n-pentane C5H12
n-hexane C6H14
n-heptane C7H16
n-octane C8H18
n-nonane C9H20
n-decane C10H22

Rules for naming acids

An acid is a substance that produces hydrogen ions in a solution. If the anion does not contain oxygen, the acid is named with the prefix -hydro and the suffix -ic attached to the root name for the element. When the anion contains oxygen, the acid name is formed from the root name of a central element of the anion or the anion name, with a suffix of -ic or -ous. When the anion ends in -ate the suffix -ic is used. When the anion name ends in -ite the suffix 0ous is used in the acid name.

molecule test

Today we took a test based on molecules. Learning about molar masses and how to calculate the amount of moles, we were able to figure out how many atoms there were. A lewis structure is a representation of a molecule or polyatomic ion showing how valence elctrons are arranged among the atoms in the ion. A duet rule is surrounded by two electrons while an octet is surrounded by eight electrons. A bonding pair is a pair of electrons that are shared between two atoms forming a covalent or polar-covalent bond. A single bond is a covalent or polar covalent bond in which two pairs of electrons are shared by two atoms.