Check out the prezi for a summary of our 2 week experiment
You’ll find out what our students thought of the experiment. I hope you enjoyed it as much as we did and find their reflections helpful!
Category Archives: Uncategorized
Oxidation Number Calculation
One of the most necessary procedures in Chemistry is learning how to calculate oxidation numbers. Oxidation states are straightforward to work out and to use, but it is quite difficult to define what they actually are in any quick way. How do we calculate oxidation numbers?
First off, an oxidation number is the the degree of oxidation of an atom, ion, or molecule; for simple atoms or ions the oxidation number is equal to the ionic charge.
For example, the oxidation number of hydrogen is +1 and of oxygen is -2.
It helps to use a periodic table to determine oxidation numbers.
In between +2 and +3 we do not assign any numbers because there tends to be more than one oxidation number assigned to those elements.
Although the above method is dependable, oxidation states change. Elements can be oxidized or reduced.
- Oxidation involves an increase in oxidation state or the decrease in number of electrons
- Reduction involves a decrease in oxidation state or the increase in number of electrons
Recognising this simple pattern is the single most important thing about the concept of oxidation states. A few rules to follow when looking for the oxidation number include:
- The oxidation state of an uncombined element is zero. That’s obviously so, because it hasn’t been either oxidised or reduced yet! This applies whatever the structure of the element – whether it is, for example, Xe or Cl2 or S8, or whether it has a giant structure like carbon or silicon.
- The sum of the oxidation states of all the atoms or ions in a neutral compound is zero.
- The sum of the oxidation states of all the atoms in an ion is equal to the charge on the ion.
- The more electronegative element in a substance is given a negative oxidation state. The less electronegative one is given a positive oxidation state. Remember that fluorine is the most electronegative element with oxygen second.
- Some elements almost always have the same oxidation states in their compounds but some, like Hydrogen although usually +1, can be different.
A few examples that you can work out are below.
What is the oxidation state of chromium in Cr2+?
For a simple ion like this, the oxidation state is the charge on the ion – in other words: +2 (Don’t forget the + sign.)
What is the oxidation state of chromium in CrCl3?
This is a neutral compound so the sum of the oxidation states is zero. Chlorine has an oxidation state of -1. If the oxidation state of chromium is n:
n + 3(-1) = 0
n = +3 (Again, don’t forget the + sign!)
I hope this helps you as much as it has helped me.
-Nnana Amakiri
Energy and Temperature Dependence
How does energy and temperature affect reaction rates? I grew interest from this topic when I sought to gain a deeper and more clear understanding of how energy and temperature affect the rate of a reaction.
Consider the reaction from a chemical reference online:
H2 + Cl2 -> 2HCl
On a molecular level, bonds must be broken (H-H and Cl-Cl) before the reaction can proceed too far into products. This means that as the reactant molecules come together, the collision must have enough energy to initiate the bond breakage for the reaction to occur. Not all collisions will have this amount of energy. The collisions that do not have sufficient energy to react end up as elastic scattering events. Dictionary.com shows that Elastic suggests that it is able to maintain its shape or speed after a collision.
Only collisions with enough energy react to form products. The energy of the system changes as the reactants approach each other. The critical amount of energy to make the reaction proceed is called the Activation Energy.
The picture below comes from our chemistry textbook and details the amount of energy needed in a reaction.
From Wikipedia we are told that each reaction rate k has a temperature dependency which is usually given by the Arrhenius equation:
Ea is depicted as our activation energy or the amount of energy needed for the reaction to occur. R represents the gas constant. T represents temperature.
What is important to take from this is that when you conduct a reaction at a higher temperature, you deliver more energy into the system and increase the reaction rate by causing more collisions between particles, as explained by collision theory. However, the main reason that temperature increases the rate of reaction is that more of the colliding particles will have the necessary activation energy (Ea) resulting in more successful collisions (when bonds are formed between reactants).
Ex:
Coal burns in a fireplace in the presence of oxygen, but it does not when it is stored at room temperature. The reaction is spontaneous at low and high temperatures but at room temperature its rate is so slow that it is negligible. The increase in temperature, as created by a match, allows the reaction to start and then it heats itself, because it is exothermic. That is valid for many other fuels, such as methane, butane, and hydrogen.
Energy and Temperature can greatly influence the presence or the rate of a reaction
Nnana Amakiri
Civil Rights Movement. CIVIL Rights Movement.
Dr. Glaud spoke to us week ago about several coordinating points that make up America’s history. One was America as a myth, the next was historical rupture, than the Civil War, than the Black Freedom Struggle, and finally the Barrack Obama era. In understanding the civil rights movement the fourth coordinate, Black Freedom struggle, was most important. It was then in which we expanded how we saw ourselves as a nation and the conception of citizenship will not be based on one’s whiteness. Glaud’s believes history in the United States has always had a tenuous position, a conception of America as a chosen (innocent). However, America has always been a country in which gratuitous unjust ways coincided. The Black Freedom Struggle came from the help of men and women like Martin Luther King, James Baldwin, Rosa Parks, and movements such as the Harlem Renaissnce. However, I believe it continues today.
The world we live in today is not a world of civil justice. We are both still separate and still not equal. Cities like Newark are with many poor people and impoverished by homeless black people. I use the word impoverished because black is looked at as the underdog, those who have to work extra hard to make something of their lives because of the stereotypes associated with their color. I do not believe the goals of the civil rights movement were achieved because we are nor equal or together.
But of course one must ask themselves what the goal of the civil rights movement was. Easy, to achieve civil rights for all people. Then what are civil rights? Rights and concerns of ordinary citizens. Would the Civil Rights movement be happy if this was all they hoped to achieve? Yes. However, with all the racist remarks heard in the world today, they would not and did not stop now. Thats why organizations like the NAACP still exist. There is still a job to do. In conclusion, although the world is not as equal or just as it could be, the Civil Rights movement did give all people civil rights but the job is not done there.
A Word, Symbol, Often Misused, Often Misunderstood
While at the African American slave boat memorial in Harlem, NY, I was mesmerized by its astounding beauty and purpose. The following phrase affected me the most:
For all those who were lost
For all those who were stolen
For all those who were left behind
For all those who were not forgotten
So many memorials tend to the harsh reality that indeed the people were hurt but forget to mention that they will never be forgotten. This memorial was one of the more striking memorials I have ever seen and I hope one day will be what is written on my grave in honor of not only me but all people who have been forgotten. Through and inside the memorial, I noticed a lot of images around me with particular meanings. Inscribed in the walls around, there was a particular picture that I took interest in. It was a heart, and under that heart was the word endurance. I thought about that word and I realized that the heart is an organ that tries it’s absolute best to endure always. Than I correlated this understanding to relationships and love. The heart is a symbol commonly used to represent love and relationships. I thought to myself how we endure when we love one another and I realized that we endure through the good and the bad times for one another. But more importantly, we live because when we die, others will have to live with the pain of knowing that your gone. So we endure when we love someone. We endure through all of our troubles because we love that somebody, those people. We love them, and would never want to hurt them. We endure (remain in existence) like our heart, because we love. Making the heart the perfect symbol.
Langston Hughes (Cross)
Langston Hughes was born in Joplin, Missouri. His mother wrote poetry and was black, his father was a black storekeeper. His parents split, leaving his mother to struggle going from city to city in search of work. He spent a part of his childhood with his grandmother, and became successful. He entered Columbia University as well as Lincoln University. Hughes was a voice in the 1920s during the Harlem Renaissance that had not quite existed like any other before. He was a perfect example of how Dubois’ idea succeeded because he stuck to his roots, understood it, and expressed his beliefs, reaching out to thousands and thousands of people. He wrote “Cross,” that I read several years ago and that I have not forgotten because it still lives inside of me. He wrote:
My old man’s a white old man
And my old mother’s black.
If ever I cursed my white old man
I take my curses back.
If ever I cursed my black old mother
And wished she were in hell,
I’m sorry for that evil wish
And now I wish her well
My old man died in a fine big house.
My ma died in a shack.
I wonder where I’m going to die,
Being neither white nor black?
To me, this poem was extremely power despite not being mixed like he describes. It is here that he sympathizes with those that are mixed and expresses his understanding. In describing what he might have said to both his parents he says about his dad that he “takes (his) curses back” and to his mom, “If ever (he) cursed (his) black old mother and wished she were in hell, (he’s) sorry for that evil wish.” He did not ever mention wishing his father was in hell. Therefore, as a reader, you are led to believe that mixed children of that time believed they were neither black nor white and could not fit in. It is here that Langston Hughes also unleashes stereotypes of both black and white people and acts as though one would want to be more like the white in this scenario. He says that the black mother died in a shack while the white father died in a fine big house. In other words, the white man was rich, the black man was poor. I could never quite understand why Langston Hughes, a man who hopes that his people will learn to appreciate themselves and understand who they are, would ever say such a thing. Thats why Mr. Hughes was so intriguing. He spoke the truth no matter how hard it was to hear, but in the end there was always something positive to look on. Hughes said he wished his mother well but did not say anything about wishing his father well. Because although the mother put the child through hell, she took care of him, and he loved her.
Great Grandfather, Great Icon
Nnana. That’s my great grandfathers name. Born and raised in Imo State Nigeria, my great grandfather was a prominent leader in his town. He was a certified medical doctor as well as a preacher in one of the biggest Churches in the state. My great grandfather gave birth to many, many children (7). One of them includes my grandfather, my mother’s father, Agustine. I am fascinated by the journey my family took to get to the United States but more fascinated by the legacy they left behind. My great grandfather was elected “Eze” which means king in Igbo, one of many Nigerians languages. He was “eze” of the town, Ezuido. Everytime I go to Nigeria, my family and I are treated with the highest respect and we know it is because of what he has helped done. He has helped create a pathway for my mother to come to the United States of America. He was a great, wealthy, respectable man who gave back and died having a Church name pews after him, a school named after him for his leadership and a program named after him. He is a true leader and has been rewarded. In the very few times I’ve been to Nigeria, my family and I have been treated like kings. Especially me because I have his name and look a lot like him. Now, the reason why I was given his name is quite simple. Nnana Agustine Amakiri died on the day I was born (October 31st), and so did his son, Agustine Nnana Amakiri (October 31st, 1995). And, now, I live in honor of my great and grandfather, given the name, Nnana Agustine Amakiri because I was born on (October 31st, 1995). I feel honored to be born on the day both my ancestors died and I feel honored to carry both of their names and their legacies. People ask me sometimes, what kind of name is that? And I answer, it has far more meaning than you would think.
Namakiri 