Reactions: Equations

By: Cameron Ogle, Ponni Theetharappan, Shriya Vohra, and Michael Whitmayer

**Chemical Equations!**

Balancing Chemical Equations

1. Write a skeleton equation that shows the correct chemical formula for reactants and products.

2. Determine the number of atoms of each type on each side of the equation.

3. Use coefficients to balance the equation. Subscripts should never be changed.

4. Make sure that you have the smallest possible whole number coefficients.

Example:

? CH4 + ? O2 -->→ ? CO2 + ? H2O

H 4 2

C 1 1

O 2 3

Background Continued:

Writing Balanced Equations

1. Rewrite the given information into a chemical equation.

2. Use the balancing chemical equations steps given before to finish balancing the equation.

Summary

The Law of Conservation of Mass states that matter and mass energy are neither created nor destroyed.

We use certain special symbols to help us write a chemical equation, in addition to key parts of the equation.

To balance a chemical equation, there are four steps.

Using your knowledge of elements and their charges, you can write your own equations just from descriptions.

Background:

Law of Conservation of Mass -

Matter cannot be created nor destroyed; it only changes forms.

Chemical Equation

- a representation of a chemical reaction using symbols of the elements to indicate the amount of substance.

Coefficients

- Show the number of molecules or atoms that were involved in an equation

Balanced Equation

- An equation where the total number of atoms for each element is equal in both the reactants and the products.

1 CH4 + ? O2 -->→ ? CO2 + 2 H2O

H is easy: we just have to double it on the left side to make both sides have 4.

(g) = Gaseous state

(l) = Liquid state

(s) = Solid state

(aq) = aqueous state

( ) = Delta means change

1 CH4 + ? O2 -->→ 1 CO2 + 2 H2O

Looking at carbon, you can see that the 2 compounds with carbon must have the same coefficient because the number of carbons is equal on both sides.

Works Cited

http://www.chem4kids.com/files/react_intro.html

http://chem.wisc.edu/deptfiles/genchem/sstutorial/Text1/Tx14/tx14.html

Chemistry: The Central Science

by Brown, LeMay, and Bursten

2. Write a skeleton equation that shows the correct chemical formula for reactants and products.

3. Determine the number of atoms of each type on each side of the equation.

4. Use coefficients to balance the equation. Subscripts should never be changed.

5. Make sure that you have the smallest possible whole number coefficients.

1 CH4 + 2 O2 -->→ 1 CO2 + 2 H2O

Now, there are a total of four oxygens on the right side, and we need to balance that by changing the value of the O coefficient.

Example:

iron+sulfur ----> iron(ii) sulfide

Solution

Fe+S ---> FeS2

_Fe 1Fe

_S 2S

1Fe 1Fe

2S 2S

Fe+2S ---> FeS2

Lastly, ChEcK YoUr WoRk

Lastly, check your work. Add up the number of atoms for each element on either side of the equation. Do you get the same value?

+/-

: These represent the charge of an atom or equation.

-->

: This represents changes in a chemical equation

The left side includes the

reactants

, or the starting material in a chemical reaction.

The right side includes the

products

, or the ending material in a chemical reaction.

1. Write a skeleton equation that shows the correct chemical formula for reactants and products.

2. Determine the number of atoms of each type on each side of the equation.

3. Use coefficients to balance the equation. Subscripts should never be changed.

4. Make sure that you have the smallest possible whole number coefficients.