RedOx Reactions & Oxidation Numbers

Today's lesson was more on the difficult side for me. I was fine with double replacement, but I'm a bit iffy on the acid base reactions and the redox ones we learned about today. There is a lot to memorize, and some aspects are confusing. I think I will just need to watch some review videos and do vigorous sessions of practice.

http://www.kgs.ku.edu/Hydro/GWtutor/Plume_Busters/remediate_refs/redox_chemistry.htm

To summarize, redox reactions are reactions in which electrons have been transferred. This transfer can be separated into either reduction or oxidation, memorized by the mnemonic, OIL RIG. This means "Oxidation is Losing (Electrons) and Reduction is Gaining (Electrons)". We also learned about oxidation numbers in which each ion/element follows a set of rules to determine the number of electrons they lose/gain.

I am a bit worried for Thursday's unit exam, as I am still confused on some portions of this unit. I should study. A lot. Bozeman's video on Redox reactions helped with today's lesson, and I plan on looking at Crash Course's as well.

Quiz and Lecture Reflection

The 11 question quiz we took today was not bad in means of content, but the timed aspect of it gave me much stress. Additionally, I kept getting the wrong balance for the balancing equation questions, and I had to use extra time to focus on those to make sure I was getting the right balance. And even further, I didn't have much time to look over my answers. I really need better time-management skills, especially when under pressure.

http://study.com/academy/lesson/neutralization-reaction-definition-equation-examples.html

In other news, the lecture today on acid-base reactions was new and a bit difficult, as it's very different than the reactions we've been learning about so far. We'll definitely have to know what distinguishes strong v. weak acids/bases, which is what makes it so complicated for me. I don't really understand the difference between a strong and weak acid or base. This video from Crash Course looks pretty helpful.

Chemical Reactions Lab

Friday's lab was a lab I thoroughly enjoyed! The lab had us combining various substances and seeing whether they'd have a chemical reaction or not. For the most part, our predictions were correct. We found two exceptions to the solubility rules. Potassium iodide and copper chloride would not have a reaction based on the solubility rules, but did indeed have one when we combined the two substances in lab. Additionally, we predicted that some reactions would result in a product of lead chloride, but lead chloride is actually soluble. It was really fascinating to watch how once one substance touched the other, the product immediately changed color or texture. Some products were really cool-looking while others produced an unpleasant color and texture. 

I see you, Column 1 Row 2!! (One of the most unpleasant substances)

On another note, we have a quiz tomorrow that will only contain 11 questions. One part of me is extremely grateful as it's very short, but another part of me is dreading it and fearing that I will miss some questions, giving me a much higher chance of getting a bad score on it. We'll see though.

Describing Chemical Reactions

Our lesson today revolved around breaking a molecular chemical formula, which uses the double replacement we learned yesterday, into a complete ionic formula, which shows the charges of each ion found in each reactant and product. Finally, that complete ionic formula can be reduced into the net ionic formula, which cancels out all repeated ions. I thought this lesson was pretty simple, no tricks or anything. The lesson used a lot of the solubility rules which are still pretty difficult for me to remember as there are many exceptions to each rule.

https://www.pinterest.com/pin/393220611187663524/

Tomorrow is a lab day, and I am super stoked for it. It seems really fascinating and cool, and I cross my fingers that me and my lab partner will get into lab.

On a side note, I got my grade back for the last unit exam, and even though I did not receive a bad score, I'm not 100% happy with it, ya know? I'd wish I'd prepared some more which would've helped (BICARBONATE!!!!!!!).

Kick-off to Chemical Reactions

Yesterday, we started our Chemical Reactions unit. We first learned about balancing equations. This was pretty basic, and it was almost like chemistry commen sense. Of course you have to make sure both sides of the reaction are balanced in terms of charge and amount of atoms/ions. We also learned the CHO method.

https://www.pinterest.com/pin/45528646206046702/

Today, we had a lesson on predicting chemical yield. As I came into class about halfway through due to club pictures, I missed a large chunk of the lecture, unfortunately. However, I got the notes from my lab partner, yet I was still slightly confused on the stuff I had missed. After a bit of practice, I think I have the hang of it. One thing I need to look over a lot is the solubility rules for Friday. It'll be rough. Wish me luck.

Chemical Composition Test Reflection

After taking the unit test today, I believe it is safe to say that I am smiling on the outside, but feeling pain on the inside. I studied a lot for this test, and even then, I don't think it was enough to prepare me for today. The majority of the questions were moderately easy, but I didn't get a chance to double-check them, so I pray to the chemistry gods that they were correct. The rest of the test, I was either confused on the wording, completely blanked on how to solve them, or simply didn't know how to do them. I guessed on roughly five of the questions which isn't too bad, I guess. We'll see though...

https://raymcdonald.wordpress.com/2011/11/09/caste-your-anxious-moments-on-jesus/

Throughout this unit, the majority of the concepts were not difficult at all, I guess just applying those concepts on the test was what made it so difficult. I am definitely going to need to review this chapter for the final exam. This is probably the first chemistry exam/quiz that I have not felt fairly confident in my answers. I'm really hoping that I did decent on it.

Formula of a Chloride Lab

I think with all this practice, these empirical formulas are becoming easier and easier to solve. Today's pre-lab quiz was really simple, and I was stoked that we were able to confer with our partners. It allowed me to catch some simple calculation errors that would've maybe given be the incorrect answer. However, I think the concept of finding empirical formulas is very simple. I just need to practice and memorize some more. The lab we did today was similar to Monday's lab, except this time, we heated zinc and hydrochloric acid. After a couple minutes on the hot plate, the zinc would dissolve into the acid, as shown in this picture.

The resulting product was a solid resembling table salt. 

Like the Formula of a Hydrate lab, we took the masses of the beaker, beaker plus zinc, and beaker plus zinc/acid. These masses would be used at the end to calculate the empirical formula of zinc chloride.

Overall, this lab was interesting. The only thing I absolutely despised was the SMELL of the chlorine gas. It smelled kind of like metal, but VERY pungent metal. Looking forward to future labs.

Empirical Formulas

Today's lesson was pretty simple, but chockful of tedious types of problems. We finally learned what empirical formulas are, as many empirical problems were on the pretest which I did not understand at all. However, after the lesson today, I am now aware that they are really simple. Empirical formulas are simply the lowest whole number ratio of the elements in a compound. For example, H2O is an empirical formula as the numbers of elements cannot be reduced any further. On the other hand, N2O4 is not an empirical, rather a molecular formula because it can be reduced. When it is reduced to NO2, it becomes an empirical formula. So, pretty straightforward. We also learned how to find the empirical formula of a compound using a given mass or percent of an element in that compound. 

Here are some empirical formulas practice websites: Chemistry.about and SoftSchools

Bozeman Science also has a video that contains some empirical formula lessons.

I am looking forward to our lab tomorrow. Hopefully, I will be able to look over the lab and my notes tomorrow and a bit tonight as I have not had much time due to having to stay at school until after 8 p.m for the fall play tech week. BTW,  everyone should come to the play!! Opening night is tomorrow at 7 p.m, and tickets are 5$. I'd love to see some of my chem pals support drama club!

Formula of a Hydrate Lab

On Monday, we had our pre-lab quiz for the copper sulfate hyrdate lab. To my relief, my partner and I both passed! I had been stressing over it for the entire day, so I was very glad to have passed. We first took the mass of the test tube and then the mass of the test tube and the copper sulfate. Next, we used the bunsen burner to heat the substance until it turned white, indicating that it had changed into an anhydrous salt. Apparently, we were supposed to take the exact number that was shown on the scale, but instead, we rounded the mass numbers to the nearest thousandths as that was what was on the lab paper. This led to a large percentage of error when we calculated for "n" of the hydrate based on our mass numbers. It was actually 14%! We went back and tried to recall the exact numbers that were on the scale. We also had to reweigh some of the items to get the accurate mass reading. When we re-calculated for "n" with our more accurate mass numbers, we still got about 14% error. Our last option was to heat the substance some more, making it much more whiter. This led to a decrease in the mass of the test tube plus the anhydrous salt. With THIS new mass number, "n" was much closer to the needed value of 5, giving us only a 1% error!

Final thoughts on the lab: I believed it was a pretty interesting lab; It was super cool to watch the blue gradually turn into white as the water evaporated. Hopefully, next time we will remember to use the whole mass reading on the scales to prevent errors.

Hydrates and Anhydrous Salts

On Friday, we learned about hydrates and anhydrous salts and how to solve conversion problems with them. I believe that these past couple conversion lessons are pretty easy with a lot of practice. It is however difficult to remember all of these rules and formulas for various types of problems, but I just need some more practice. The big picture idea for this lesson is that hydrates are substances that contain water molecules, and anhydrous salts are substances that previously contained water molecules. When water is removed from the hydrate, the anhydrous salt is what is left over. ChemTeam  contains some good practice problems for figuring out the formula for a hydrate.

http://fphoto.photoshelter.com/gallery/Compounds/G0000P8DRfn82fkA/C0000AGiG6IN5fGI

We have a pre-lab quiz coming up on Monday which I am extremely anxious about. I have been studying quite a bit, but I am worried that a question will completely throw me off, and I won't be able to participate like during the Aspirin Lab. I will be practicing those hydrate problems to become more efficient at doing them in order to use my time wisely during the pre-lab quiz. The lab looks very interesting, and I very much hope I will be able to participate. Fingers crossed.

First Lessons on the Mole

Today and Wednesday were lecture days. After being so confused while taking the pre-test, I was surprised to learn how fairly simple these first couple concepts are. It is mainly converting moles into various units and vice versa for both elements and compounds. Doing more practice will definitely make me more efficient at doing these sorts of problems. This site, Chemistry.wustl.edu, looks very helpful. I believe I have stated before that one of my favorite chemistry videos to watch are Bozeman videos; this one corresponds to the Mole lesson. Another video of his that is very detailed and easy to follow is this one explaining mole conversions.

http://t-shirtguru.com/2013/01/31/mole-problems-t-shirt-mentalfloss/

At first, I was a bit confused since I thought that moles and molecules were the same things, but in reality, moles are just a unit of measuring particle amount. Moles can either be of atoms of an element or molecules of a compound. Additionally, it will be crucial to memorize those polyatomic ions and nomenclature rules. I will definitely be reviewing those as making a naming mistake leads to wrong answers.

Chemical Composition Pre-Test

Today we took our unit pretest on chemical composition. The test contained questions regarding density and molecules. I was uber confused on the questions asking how many molecules in a specific mass or volume. Some questions I tried and re-tried calculating, but it didn't work, so I just guessed. This unit seems to be one of the harder units. I hope those confusing concepts will be made clear after the lectures. One concept I had not ever heard of were empirical formulas.

http://jencrazyscience.blogspot.com/2012/09/chemical-composition-of-earth.html

I am very curious as to what and how to calculate problems according to molecular mass. I also need to review the poly-atomic ions. Additionally, I am also very interested as to what the project/lab will be for this unit.

Reflection of the Measurement Unit

This unit has drawn to an end as we took our unit test on Thursday. Overall, this unit was not too difficult for me. Some concepts, such as significant figures, took a bit more of review and memorization, but after a bit of practice, I got them down completely. I practiced using Science Geek and KhanAcademy. However, the actual unit test, I am not so confident about. The majority of the test covered the basics of what we learned and were fairly simple, but many questions combined sig figs and dimensional analysis and took a VERY long time to answer. I had to triple check my answers, and some questions I did not even have time to look back at which makes me very worried. Nearing the end-of-class bell, I was frantically trying to recalculate my answers to make sure they were right. Hopefully, I am. 

One thing I was definitely not confident about were the dimensional analysis questions that required MULTIPLE steps, much more than the ones we practiced in class. I will look over this site for some additional help. This video from Crash Course also looks promising.

http://brookdale.jdc.org.il/?CategoryID=311

Reflecting on the party on Friday, I thought everyone brought in some delicious food. However, it didn't help that I came to class with a full stomach, so I was not able to enjoy everyone's food to the full extent. Good job everyone though!