#
Avogadro's Law

##
Basic Concept

####
Avogadro's Law

Avogadro's Law states that for a gas at constant temperature and
pressure the volume is directly proportional to the number of moles
of gas.

According to Avogadro's Law:

V1 / n1
= constant

After the change involume and mole number,

V2 / n2
= constant

Combine the two:

V1 / n1
= V2 / n2

When any three of the four quantities in the equation are known, the
fourth can be calculated. For example, if n1,
V1 and V2
are known, the n2
can be solved by the following equation:

n2
= V2
x (n1/V1)

####
Pressure

The force exerted per unit area of surface, typical pressure units
are ATM, mmHg
and kPa.

####
Volume

The measurement of space taken by a substance, it is length cubed,
typical units are L,
mL and m3.

####
Temperature

A measure of the average kinetic energy of the particles in a sample
of matter, expressed in terms of units or degrees designated on a
standard scale. Typical units are K,
F and
C.

####
Density

The mass of the object divided by its volume. Typical units are
g/mL
and kg/m3.

####
Formula Weight / Molecular Weight (MW)

The formula weight of a compound is the sum of all the atomic weights
of the elements present in the formula of the compound. Some text
also refers it to formula mass. Typical unit is
g/mol.

####
Mass and Mole

Mass is the amount of a substance in grams, also called weight.

####
Gas Constant (R)

The constant that appears in the ideal gas equation (PV=nRT).
It is usually expressed as 0.08206 L
x atm/K
x mol or
8.314 J/K
x mol.

####
Molality

The number of moles of solute dissolved in one kilogram of solvent.

####
Molarity

The number of moles of solute in one liter of solution.

##
Feature Overview

With four quantities in V1
/ n1 = V2
/ n2
equation,
given any three, the forth one can be calculated based on the
Avogadro's Law.

In addition to the problem solving module, the "Show Work"
is also displayed along with the solution to illustrate the
step-by-step guide in how your problem has been solved.

##
User Instructions

This is one step process, enter the known data and press **Calculate**
to output the unknowns.

1. Select **Avogadro's Law **link
from the front page or **Avogadro**
tab from the **Gases** module.
The Input and Output screen appears.

2. In the **Input** area, enter
the three known quantities with a proper significant figure. Select
the units associated with the input.

3. Click **Calculate** to output
the answer.

4. The **Show Work** area on the
right shows you step-by-step how your problem has been solved.

To start a new problem, click **Reset**.
All Input fields will be cleared. Follow Step 1-3 again.