Transfer of Electrons: Redox Lesson

Tuesday in class we were taught a lesson over redox reactions and the different types there are. Redox reactions consist of electrons being transferred from the metal to the nonmetal. If a species loses electrons, it is said to be oxidized, and this is considered the reducing agent. If a species gains electrons, it is said to be reduced, and this is considered the oxidizing agent. An easy way to remember this is from the acronym OIL RIG. It stands for: Oxidation is loss; reduction is gain. Here's a visual for it:

http://www.ict4us.com/r.kuijt/images/en_oxidation_reduction.jpg

The first type of redox reaction we learned of was redox single-replacement reactions. In this reaction, the metals have changed places, the reaction is based on reactivity, and the driving force is the transfer of electrons. For this type of reaction, it it good t remember that "like attacks like". In this way, metal attacks a metal, while a nonmetal attacks a nonmetal.

The second type we learned of was synthesis. These reactions happens when two or more reactants come together and form one product. So A+B creates AB. Decomposition is the exact opposite of this, so there is one reactant breaking down to two or more products. This would then be AB creates A+B. 

Here are some examples of synthesis reactions:

http://www.biochemhelp.com/images/synthesis-reactions.jpg

The final type we talked about was combustion reactions. In this type of reaction, when a hydrocarbon reacts with water, the products are always water and carbon dioxide. Here is an example:

Here are some video's to further explain these concepts:
https://www.youtube.com/watch?v=RX6rh-eeflM
https://www.khanacademy.org/science/chemistry/oxidation-reduction/redox-oxidation-reduction/v/oxidizing-and-reducing-agents-1

Acid Base Reactions Lesson

Monday during class we took our notes on reactions between acids and bases. These types of reactions will produce a water and a salt, and the water produced is the driving force of this reaction.
Here's a small example of what it would look like:

http://lrs.ed.uiuc.edu/students/mihyewon/images/HClNaOH.gif

Within the acid-base reaction, there is a possibility for both strong acids and bases, as well as a weak version of both. Here are some characteristics of both.

strong acids:

• produce H+
• protonate completely
• HCl, HBr, HI
• are the strongest if the oxygens outnumber the hydrogens by 2 or more

strong bases:

• contain an -OH- anion
• disassociate completely 
• all group 1 and 2 metals plus the -OH anion are the strongest

weak acids:

• do not protonate completely
• are not on our memorized list

weak bases:

• do not disassociate completely
• are not on our memorized list

A good thing to remember is when looking at the molecular diagram, to always look for the parents. If there are more parents, this means it is weak, or if there are less, it is strong. 

http://mgh-images.s3.amazonaws.com/9780073402680/5120-4-3IRC1.png

Here's a link to walk through the solving of these problems: http://science.widener.edu/svb/pset/acidbase.html
Here's a video for further explanation: https://www.youtube.com/watch?v=ANi709MYnWg

Driving Forces

This lesson was what I believe will be the first of many confusing ones. Our teacher, Mrs. Frankenberg began to teach us what driving forces are, and at least one of these must be present for two separate components to react. The various driving forces are the formation of a solid, liquid, gas, or the transfer of electrons. Driving Forces Video For Help
This lesson was focused on the formation of a solid product from aqueous reactants. This reaction is what is called a double replacement reaction where two different compounds react to create two different compounds, by switching the positive ions, or cations switching in the products. For this to occur, the products must be aqueous and ionic, and one of the products must be a solid, and in order to know which compounds are solid, we have to memorize the solubility rules.
Here are those rules:

https://45.media.tumblr.com/tumblr_ly36p9y1NI1r0vb3to1_500.gif

This is the standard for this type of reaction:

http://study.com/cimages/multimages/16/double_displacement_reaction.png

Chapter 7 in Class

Lately in class, we have started a new unit in class over chemical reactions. A few key things we learned to recognize if it is a chemical reaction is if: 1.) color changes 2.) a solid forms (this would be a double replacement reaction-precipitate) 3.) bubbles form 4.) heat and/or a flame is produced, or heat is absorbed. Some of the other basics we learned is within the reaction, everything to the left of the arrow is called reactants, while everything to the right is called products. Next, there are four main labelings we have been doing, these being gas (g), liquid (l), solid (s), and aqueous (aq), and these all play a part in how you go about breaking down and figuring out equations. Next, we learned that subscripts tell the number of atoms of each element in a molecule, and coefficients tell the number of molecules, and these are both clear when combining elements and balancing. This balancing I mentioned is also something we learned; it is making both sides of the reaction equal or balanced in the number of elements that are present on each side.
Here is a helpful video I found that reinforces all these basics: https://www.youtube.com/watch?v=sROBNKKJwfY

Solubility Lab

Friday in class we did a lab called the Solubility lab, and of course we had to pass a pre-lab to get in first. At first I did not get in because I did not properly finish the problem, but we were shown what we did wrong, and as long as we promised to never do it again, we got into the lab. The night before the lab, we were given a table where there were around 45 different double replacement or precipitate reactions. To prepare for the lab, we predicted the outcomes of the reactions, to whether it would form an aqueous product or a solid. Aqueous is a term that we learned that means it can be dissolved in water. It was very crucial in knowing the solubility rules of the products, here is a link listing all those we needed to remember:http://www.softschools.com/quizzes/chemistry/solubility_rules/quiz1333.html
Here is a picture of the chart of all the different combinations we had to predict.

Then Friday during class, we actually mixed the chemicals, and we were able to actually see in the dish if they were solid. Majority of what we predicted was right, and only a few were off, but it was fascinating to have a real- life example of what is normally seen as boring balancing and figuring out products. Here is what some of our dishes looked like after mixing:

Unit test Reflection

Today in class we took our exam over the entire chemical composition unit. There were 36 questions on the quiz, and although the material wasn't necessarily hard with all the practice I had done, it was still difficult to finish in time.The unit was mainly surrounded around moles, with conversions and using them in problems. The test included things such as empirical and molecular formulas with complex problems, mole road map conversions, molar mass, where you add up the periodic table masses, percent composition problems, and hydrated compounds. I did not do as well on the quiz, so here are some links that I used to help prepare myself:
Hydrated Compound Practice Problems: http://www.chemteam.info/Mole/Determine-formula-of-hydrate.html
Empirical formula help:http://www.chemteam.info/Mole/EmpiricalFormula.html
Molar mass explanation and quiz: http://www.softschools.com/quizzes/chemistry/molar_mass/quiz1120.html
Molar mass sample:

https://i.ytimg.com/vi/L4y8-x9ww_A/maxresdefault.jpg

Formula of a Chloride Lab

Today, we conducted a lab in class where we attempted to determine the formula of the compound zinc chloride by measuring the variety of masses when zinc reacts with hydrochloric acid. During the experiment, we had to measure the beaker, then add a pellet of zinc and remeasure the mass. Once this was done, we measured out 10mL of 3M HCl and added it to the beaker with the zinc. Once our partner group was ready, we placed our mixture on the hot plate and turned the heat up to around 7-8. We had to wait a while, and the reaction was done when there was little to none liquid left in the beaker. Once it was at this stage, we took it off the hot plate and let it cool off before recording the final mass. We used these three masses then to determine the empirical formula.
Here are some pictures from our experiment and my notecard of all our final calculations with the work!

here is a basic video on the procedure, just on a larger scale! 

https://www.youtube.com/watch?v=M2BqSLBDf00

Empirical Formulas

Today in class we learned about empirical and molecular formulas. There are a few key differences between the two including the empirical formula has the lowest whole number ratio and it cannot be reduced, where the molecular formula can have a reduction. It is also important to remember that the molecular formula can be the empirical formula. We learned how to find the empirical formula when you're given the percent composition of each element in the compound. When you are given this, you simply convert each percent first into grams (it will be the same exact number) then use the atomic number off of the periodic table to then convert it to moles. Once it has been converted into moles, then you will divide both numbers by the smaller number. If there happens to be a decimal, that decimal will be multiplied to reach a whole number. Remember to multiply the other numbers also by the whole number that got you to that whole from the decimal.
Here is an example of how these conversions are done!

https://www.chem.tamu.edu/class/majors/tutorialnotefiles/emp2d.gif

Moles and Molar Mass

The past two days we have gotten started on our new unit. The first day we focused on what a mole is, that being a quantity of measurement and shown as 6.02x 10^23 representative particles. We have walked through the steps of converting between grams, volume, and mass, ultimately with moles in the middle of this action. Here is the chart that will show this process. You use this chart as essentially conversion factors to get to where you want. On the second day we were introduced to this process with compounds rather than just one element. The difference with that process is that the atomic mass must me multiplied by the amount there are. For example, C3H8 would have to multiple the atomic mass of carbon by 3 and hydrogen by 8.

 

Here is a video I found explaining the road map: http://m.youtube.com/watch?v=mBVL0PHPrhg

Pre-Test

Monday in class we took the entire period doing a pre-test for our upcoming unit. To be honest, I was completely lost during the entire test and I didn't know how to solve any of the problems. Most of the problems were numerical, so if I didn't know the formulas of how to figure them out, I had to guess. I did some research and found some websites to help going into this unit.
This link will help with basic understanding when just starting to dig in:
http://easyscienceforkids.com/chemical-composition/
This link goes more in depth of empirical formulas and how to do the calculations:
http://pages.towson.edu/ladon/empiric.html
Here's a picture of how working out empirical formulas will look:

http://web.tenafly.k12.nj.us/~shilfstein/emp1c.gif