Redox: Transfer of Electons

In redox reactions, electrons are transferred from the metal to the non-metal. My class and I leaned that redox reactions are either single-replacement, synthesis, or decomposition and if a reactions occurs depends on the oxidation number and the oxidation series of the elements and compounds involved. More info on the oxidation rules can be found on chemwiki.

Oxidation series tell how easily an element oxidizes compared to another element. Metals only compare with metals and non-metals with non-metals. Chemprime gives a brief explanation of oxidation series.

In redox reactions, the element losing electrons are oxidized and the element that gains electrons are reduced element. The oxidized elements is the reducing agent and the reduced elements is the oxidizing agent.

Honesty I find most of this stuff confusing and am going to have to study to have any clue what to do on the lab tomorrow. I don't remember anything from the last lecture.

Acid-Base Reactions

Acid-Base reactions driving force is the productions of water. In additions, they produce a salt. Acid-Base reactions are chemical reactions that take an acid and a base to form water and a salt, which is the cations of the base and the anion of the acid. More info on acid-base reactions here.

Acid-Base reactions are similar to double replacement reactions, but differ in the fact that they only have one ionic compound while double replacement has two. Reactions also differ in the fact that weak acids and bases can effect the outcome differently than strong acid and bases. Basically strong acids and bases completely disassociate while weak acids and bases don't. More information on the specifics can be found here.

Chemical Reactions and Precipitation

Another long and hard unit where nomenclature is crucial to the success on the tests and quizzes. Chemical reactions is the topic of this unit, where I have to learn if and how two different chemicals join together in a chemical reaction. Reactions only occur if their is a driving force present in the products of the chemical equation. We leaned that chemical reactions either: form a solid, form water, transfer electrons, or form a gas. First we went over double replacement reactions, which form a solid from two aqueous solutions, and is one of the four basic chemical reactions. More information on them here.

To be able to successful complete double replacement reactions, I need to know my nomenclature and solubility rules. Here is a quiz on the rules.

Chemical Reactions Lab

This is our first lab of the chemical reactions unit and it was pretty cool. We mixed 10 drops of 9 different kinds of chemicals with each other and saw which ones reacted and which ones didn't. A little less than half changed colors, which means the two chemicals had a reaction with each other. All of the reactions where called precipitation reactions, when two soluble salts combined together to get one insoluble one. Below is a picture of one of the plates of mixed chemicals.

Post-Test Terrors

Oh my, hardest test ever. I've never seen a test where so many people in my class, way over the majority of the class, not finish, many of the people weren't even close. In hindsight I should have have studied a little bit more, especially my polyatomic ions. I ended up forgetting what the formula for bicarbonate was, and was unsure on a few others, probably should have done this a couple of times before hand. I also missed an easy question because I thought 6.02 x 10^23 was Mendell's constant and not Avogadro Number so that stinks. Ended up guessing on like 7 questions, but was happy she gave an free one (just told us which one to circle).

Upcoming Test

I hate Monday tests. Or at least extremely dislike. It means I have to study over the weekend or at least look over the materials and I'm not a huge fan of that, rather do that on the weekdays.

Over all I think I'm gonna gonna do pretty well, at least on the first half of the unit. I ended up getting 15 out of 17 correct on the test, or a 88%. I'm still kind of confused at the point of the both empirical and molecular formulas, and when I think upon it further, the latter of the two makes more sense. Why would there be a formula which isn't even the actual formula of the compound (empirical)? Found some more information upon both of these formulas here.

Empirical and Molecular Formula

The empirical formula is the simplest formula for a compound. This is different form the molecular formula, which is based of the actual number of atoms in a compound. Now I don't really understand why there are two types of formulas if the both tell you basically the same thing. I would think that all formulas would be reduced down to their simplest form anyways.

This chart shows the difference, and sometime there's none. The way to find the empirical formula from just knowing the elements present and the percent abundance is kind of confusing but manageable. The math behind it can be found here.

Post Quiz Thoughts

Just had the weekly quiz today, and oh my. It really wasn't that terrible, but the first question made me think my teacher had it in for me. It was one of those multiple step problems and in hindsight I did it totally wrong. Turns out I should leaned about converting moles into volume of gasses, as that question pertained to chlorine gas.

After the first page, which too a long time, the rest of the quiz wasn't so bad. I answered all but one other question confidently, and that was because I was totally clueless of the chemical formula of the substance mentioned in the question.

Had a lab on hydrates yesterday, and it was pretty interesting. If you want to know more about them look here. The lab was fun because I got to use a Bunsen burner for the first time, and that weird looking contraption used for starting the flame is pretty cool too. Basically we just heated the water out of a hydrate then figured out how water was in the chemical formula.

Moles and Measurement

Back to moles, the mathematical kind. Now I kinda understand how their used and what for. One mole stands for 6.02 × 10^23 representative particles. Essentially representative particles is the estimated number of particles in an sample.

Moles are used for converting the mass of an sample into the number of atoms it contains and vise versa. It kinda works like a middle man between measurements. To do these conversions, you also need to know atomic mass, which is found on the periodic table. A mole map is helpful in these conversions.

The number that is associated with moles is named after Amedeo Avogadro, who did not discover the number, but it is in tribute to him because of the accomplishments related to molecular theory he achieved in his life. More information on him is here.

Still confused? This website should help.