Describing Chemical Equations

By Sean, Frank, and Kyle.. Table of Contents1. Chemical Equations 2. Conservation of Mass 3. Balancing Chemical Equations 4. Xtranormal Video 5. Classifying Chemical Reactions6. Toondoo
Chemical Equations
A chemical equation is a way to show a chemical reaction using chemical symbols. These equations show the formulas of the compounds and the elements included in these compounds. For example, the equation 2CO ====> C2O2 shows that they both have the same amount of carbon and oxygen atoms. Every chemical equation has a certain structure. Let's take the equation 2NH3 ====>N2+3H2. The 2NH3 is called the reactant. The substances in the reactant are what you start with. The N2+3H2 is called the product. The substances in this are what you finish with in the in a chemical reaction. The ====> means yields. So you say the formula as 2NH3 yields N2+3H2. (J., Miaoulis, Cyr, V., L., Coolidge-Stoltz, Lisowski, Garbuny, Wysession, Brooks, M., V., Griffith, Linda, Carl, G., and Hall ) 


Conservation of Mass
"What happens in a chemical reaction is similar to a mathematical equation. Both sides of an equation must balance. Likewise, in a reaction, the reactants and products must contain the same number and types of atoms, though differently connected to form different molecules. This, in essence, is Lavosier's Law of Conservation of Mass" (Book, World, and Inc.).The principle of the conservation of mass states that matter is not created or destroyed during a chemical reaction. Every atom that was in the beginning of the reaction is in the end (David, Travers, and Nagel). The principle also states that the total mass of the reactant equals the total mass of the product. For example, the equation 2LiO====>2Li+2O is balanced. Since the reactant's mass is 12 grams, the product's mass is also 12 grams. This is true according to the conservation of mass. Sometimes in chemical reactions, it may appear that mass is lost. This is an open system. The mass isn't actually lost, it is just in a different form and has left the system. An example of this would be a piece of wood burning. The water in the piece of wood turned into vapor, which left the system. This caused some mass to leave the system. A closed system is when the chemical reaction doesn't lose any mass. An example of this would be if a fruit were decaying in a glass case. Since the gases cannot escape, the system still has the same amount of mass. (J., Miaoulis, Cyr, V., L., Coolidge-Stoltz, Lisowski, Garbuny, Wysession, Brooks, M., V., Griffith, Linda, Carl, G., and Hall )  


Balancing Chemical Equations
There are certain steps that you have to follow to balance a chemical equation. These are:
1. Rewrite the equation with the correct formulas Example: H2+O2

2. Count the number of atoms on both sides

3. Use coefficients to balance the amount of atoms on both sides. Coefficients are what go in front of the elements to make the reactant equal the product. Example: 2H2

4. Check your answers and see if both sides are equal.



Classifying Chemical Reactions
There are three categories of chemical reactions that are called synthesis, decomposition, and replacement. A lot of chemical reactions can be classified as one of these three. Synthesis is when two or more elements combine to make more complex elements. An example of this would be the reaction of hydrogen and oxygen to make water. Decomposition is when compounds break down into simpler substances. An example of this would be when hydrogen peroxide decomposes into water and oxygen. This would be represented by 2H2O2====> 2H2O+O2. Replacement is when one element replaces another element in a compound, or when two elements trade places in different compounds. An example of this would be turning copper oxide and carbon and heating them to form cooper metal or 2Cu2O+C=====> 4Cu+CO2. If you notice, the carbon replaces the copper in the compound with oxygen. This is also called a single replacement reaction. This is true because only one element replaces another element in the compound. There is also something called a double replacement reaction. This is when compounds appear to trade places with each other. An example of this would be
FeS+2HCl=====> FeCl2+H2S.


Synthesis


Candy 5



Resources:
J., Michael, Ioannis Miaoulis, Martha Cyr, Janann V., Donald L., Elizabeth Coolidge-Stoltz, Marylin Lisowski, Carole Garbuny, Michael Wysession, Barbara Brooks, Jay M., David V., T. Griffith, Camille Linda, Andrew Carl, Russell G., and PearsonPrentice Hall. Prentice Hall science explorer. 2009. Print.

E., David, Rob Nagel, and Bridget Travers. U·X·L Encyclopedia of Science: R-S. 1998. Print.

Book, World, and Inc . The World Book encyclopedia of science. World Book, 2000. Print.

"Chemical Reactions." www.Xtranormal.com . Web. 18 May 2011. http://www.xtranormal.com/watch/12045209/chemical-reactions.

"Candy 5." ToonDoo. Web. 18 May 2011. http://www.toondoo.com/MyToondoo.toon.