Boyle's Law (Mariotte's Law) |
Key Concepts
- At constant temperature, the volume of a given quantity of gas is inversely proportional to its pressure : V
 1/P
So at constant temperature, if the volume of a gas is doubled, its pressure is halved.
OR
At constant temperature for a given quantity of gas, the product of its volume and its pressure is a constant : PV = constant, PV = k
- At constant temperature for a given quantity of gas : PiVi = PfVf
where Pi is the initial (original) pressure, Vi is its initial (original) volume, Pf is its final pressure, Vf is its final volume
Pi and Pf must be in the same units of measurement (eg, both in atmospheres), Vi and Vf must be in the same units of measurement (eg, both in litres).
- All gases approximate Boyle's Law at high temperatures and low pressures.
A hypothetical gas which obeys Boyle's Law at all temperatures and pressures is called an Ideal Gas.
A Real Gas is one which approaches Boyle's Law behaviour as the temperature is raised or the pressure lowered.
Graphical Representations
Compression of Hydrogen gas at 25oC
Pressure
(mm Hg)* |
Volume
(mL) |
P x V |
Graph |
|---|
| 760 |
23 |
1.75 x 104 |
 |
| 912 |
19.2 |
1.75 x 104 |
| 1064 |
16.4 |
1.75 x 104 |
| 1216 |
14.4 |
1.75 x 104 |
| 1368 |
12.8 |
1.75 x 104 |
| 1520 |
11.5 |
1.75 x 104 |
Volume
(mL) |
1/Pressure
(1/mm Hg)* |
Graph |
|---|
| 11.5 |
6.6 x 10-4 |
 |
| 12.8 |
7.3 x 10-4 |
| 14.4 |
8.2 x 10-4 |
| 16.4 |
9.4 x 10-4 |
| 19.2 |
1.1 x 10-3 |
| 23 |
1.3 x 10-3 |
* A pressure of 760 mm Hg is equal to 1 atmosphere (atm) or 101.3 kilopascals (kPa)
Calculations : PiVi = PfVf
- A certain mass of gas occupies a volume of 2.5L at 90 kPa pressure. What pressure would the gas exert if it were placed in a 10.0L container at the same temperature?
Pi = 90 kPa Vi = 2.5L
Pf = ? Vf = 10.0L
PiVi = PfVf
90 x 2.5 = Pf x 10.0
225 = Pf x 10.0
225 ÷ 10.0 = Pf
Pf = 22.5 kPa
- 4.5L of gas at 125 kPa is expanded at constant temperature until the pressure is 75kPa. What is the final volume of the gas?
Pi = 125 kPa Vi = 4.5L
Pf = 75 kPa Vf = ?
PiVi = PfVf
125 x 4.5 = 75 x Vf
562.5 = 75 x Vf
Vf 562.5 ÷ 75 = 7.5L
|
|
|
 |
| |
Search this Site |
| You can search this site using a key term or a concept to find tutorials, tests, exams, drills, learning activities (games), worksheet and quiz wizards.
|
| |
Become an AUS-e-TUTE Member |
AUS-e-TUTE student members have access to the Test Centre containing:
- learning activities (games)
- drills with worked solutions
- tests with worked solutions
- exams with worked solutions
AUS-e-TUTE teacher members also have access to the Teachers Only area.
Prepare new, unique, worksheets and quizzes in seconds using AUS-e-TUTE's wizards.
Worksheets and quizzes come with answers and links to learning resources for students.
Find out more about AUS-e-TUTE membership.
Become an AUS-e-TUTE member.
|
| |
Register for your Free Newsletter |
Email  to
subscribe to AUS-e-TUTE's free quarterly newsletter, AUS-e-NEWS.
AUS-e-NEWS is emailed out in
December, March, June, and September. |
| |
Ask Chris, the Chemist, a Question |
| The quickest way to find the definition of a term is to ask Chris, the AUS-e-TUTE Chemist.
Chris can also send you to the relevant
AUS-e-TUTE tutorial topic page.
|
| |
AUS-e-TUTE's Blog |
| Read AUS-e-TUTE's blog AUS-e-BLOG. |
Keep up-to-date with - chemistry news from around the world
- updates to the AUS-e-TUTE website.
|
| |
Related AUS-e-TUTE Topics |
| Gay-Lussac's Law of Combining Gas Volumes
Avogadro's Principle
Charles' Law
Combined Gas Equation
Ideal Gas Law
Kinetic Theory of Gases
Dalton's Law of Partial Pressures
Graham's Laws of Effusion and Diffusion
|
| |
Practice |
| Calculate the final pressure of a gas using Boyle's Law
Want more practice?
Become an AUS-e-TUTE member and get access to thousands of chemistry questions.
|
| |
Bookmark AUS-e-TUTE |
 Bookmark this site!
|
| |
|
