Avogadro's law states that the volume of a gas at constant temperature and pressure is directly proportional to the number of moles of gas present. The document explains the law using examples and formulas to calculate unknown variables with given values. It also includes problems for practice related to the application of the law.

1. AVOGADRO’S
LAW

2. When you inflate a balloon, its volume increases because you add
more air molecules. If the balloon has a small hole, the air leaks
out and causes the air volume to decrease.

3. Amedeo Avogadro,
an Italian chemist
and physicist,
formulated the
Avogadro’s Law,
which states that at
constant temperature
and pressure, the
volume of a gas is
directly related to its
number of moles.
Amedeo Avogadro

4. This law is expressed as:
FORMULA
In Avogadro’s law, the following formulas
are to be used when three variables are
given and one is unknown:
Where V1 and n1 are the initial volume and
amount of gas; V2 and n2 are the final volume
and amount of gas at constant pressure and
temperature.

5. EXAMPLE:
A weather balloon filled with 2.0 mol helium has a volume of 40.0 L.
To what volume, in L, will the balloon expand if 4.0 mol of helium is
added, to give a total of 6.0 mol of helium keeping the temperature
and pressure the same?

6. EXAMPLE:
If 2 moles of a gas occupy a volume of 10 liters at a certain temperature and
pressure, how many moles of the gas would occupy a volume of 20 liters at the
same temperature and pressure?
Solution:
Given: n1​=2 moles
V1​=10 liters
V2​=20 liters
n2= ?
Formula:
n2​=V2​×n1 / v1​​
Substitute the values:
n2​= 20 x 2 / 10​
n2​= 40 / 10​
n2​= 4

7. Problem 1: If 4 moles of a gas
occupy a volume of 50 liters at
a certain temperature and
pressure, what volume would
6 moles of the gas occupy at
the same temperature and
pressure?
In a ½ crosswise paper, solve
the following problems:
Problem 2: If 3 moles of a gas
occupy a volume of 30 liters
at a certain temperature and
pressure, how many moles of
the gas would occupy a
volume of 15 liters at the
same temperature and
pressure?

8. QUESTIONS?
If you have questions feel free to
ask.