This document discusses balancing chemical equations. It explains that a chemical equation describes a chemical reaction by showing the reactants and products. It also notes that balancing a chemical equation establishes the quantitative relationship between reactants and products by using coefficients. There are three main steps to balancing an equation: 1) writing the unbalanced equation, 2) balancing the equation by applying the law of conservation of mass so each element has the same number of atoms on both sides, and 3) indicating the states of matter of the reactants and products using abbreviations like (g) or (s). An example problem of balancing the equation for the reaction of tin oxide with hydrogen gas to form tin and water vapor is provided.

1. Balancing Chemical Equation

2. What did you notice in the picture
below?
A.

3. What did you notice in the picture
below?
B.

4. Chemical Equation
• Is the chemist’s shorthand
process of describing the
course of chemical of a
chemical reaction.

5. Chemical Equation
• A chemical equation describes
what happens in a
chemical reaction. The equation
identifies the reactants (starting
materials) and products (resulting
substance)

6. Evidence of chemical reaction
• When there is a gas being
released
• Substance being dissolved
• Formation of precipitate
• Change in intrinsic property

7. Balancing a chemical equation
• refers to establishing the
mathematical relationship
between the quantity of
reactants and products.
–The quantities are expressed as
grams or moles.

8. There are essentially three
steps to the process:
• Sample problem
–Tin oxide is heated with
hydrogen gas to form tin metal
and water vapor. Write the
balanced equation that
describes this reaction.

9. There are essentially three
steps to the process:
1. Write the unbalanced
equation.
SnO2 + H2 → Sn + H2O

10. There are essentially three
steps to the process:
2. Balance the equation.
 Apply the Law of Conservation of Mass to
get the same number of atoms of every
element on each side of the equation.
Tip: Start by balancing an element that
appears in only one reactant and product.

11. There are essentially three
steps to the process:
2. Balance the equation.
Once one element is balanced,
proceed to balance another, and
another, until all elements are
balanced.

12. There are essentially three
steps to the process:
2. Balance the equation.
 Balance chemical formulas by placing
coefficients in front of them. Do not
add subscripts, because this will
change the formulas.

13. There are essentially three
steps to the process:
2. Balance the equation.
SnO2 + H2 → Sn + 2 H2O

14. There are essentially three
steps to the process:
3. Indicate the states of matter
of the reactants and products.
(g), (l), (aq), (s)

15. Sample problem:
1. KCl3 → KCl + O2(g)
2. Al + HCl → AlCl3 + H2(g)
3. Fe + O2→ Fe2O3

16. Quiz
1. KCl3 → KCl + O2(g)
2. Al + HCl → AlCl3 + H2(g)