Chemistry

Understanding Boyles Law



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Firstly, I think you guys should know just a little bit on Boyle's Life and other Interesting facts from around his lifetime.

Boyle was born on the 25th January, 1627 in Lismore, County Waterford, Ireland. His father, Richard Boyle, was the Earl of Cork, and was the richest man in Great Britain. His mother was Catherine Boyle. Robert was the seventh son, and fourteenth child, of his parent's fifteen children.

Robert Boyle, along with his brother Francis attended Eton College in England. This was a school where important people sent their sons. In November 1638, the Earl of Cork took his sons away from Eton College and Boyle was to be tutored privately by one of his father's chaplains.

Galileo's Discourses on Two New Sciences was published during the same year.

In 1642, the Civil War broke out between King Charles and the Parliament. In the same year was the birth of Isaac Newton, and the Death of Galileo.

Boyle was greatly influenced by the event of Galileo's death and he carefully studied the works of Galileo. This directed Boyle's life towards science.

The Earl of Cork died in 1643. He left a property for Boyle, the manor of Stalbridge, in England.

In 1645, the Civil war ended and Boyle moved into the manor of Stalbridge where remained for much of the next decade.

From 1648 - 49 was the second Civil war, and then King Charles was executed in January, 1649.

Boyle went to Ireland in 1652 to look after his estates there. He ended up a very rich man and was able to devote himself entirely to science without the need to earn money. He was also a very generous man with his money, and many around him benefited from his generosity.

During his stay in Ireland, 1654, Boyle became severely ill.
Boyle was appointed first Governor of the Corporation for Propagation of the Gospel in New England on the 7th February, 1662.
A year later, Boyle settled in Oxford. He made important contributions to physics and chemistry and is best known for Boyle's law. He experimented for 3 years with an air pump with the help of his assistant, Hooke, and discovered a whole series of important facts.
In 1665, The Great Plague broke out in England. It struck London particularly hard. By the year's end, some 100,000 people died from the illness.

Boyle Settled in London, living for the rest of his life with Lady Ranelagh in Pall Mall in 1667. Two years later he suffered a severe stroke.
Isaac Newton's Principia was published in 1687.
Boyle signed and sealed his will on the 18th July, 1691. Later that year, Lady Ranelagh died.
Boyle died on the 31st December, 1691. He was buried at St Martin's in the Fields.



The Contribution he made to understanding gases!

Gases have various properties that can be observed by our senses, including the gas pressure, temperature, mass, and the volume which contains the gas. Scientific observation has determined that these variables are related to one another, and the values of these properties determine the state of the gas.
Robert Boyle discovered that there is an inverse relationship between the pressure P and the volume V of a confined gas held at a constant temperature. Boyle observed that the product of the pressure and volume of a real gas are nearly constant. The product of pressure and volume is exactly a constant for an ideal gas.

=> An ideal gas is a hypothetical gas consisting of identical particles of zero volume, with no intermolecular forces.
Real gases do not have these exact properties, although the approximation is often good enough to describe real gases.

Boyle's law states that:

"The volume of a definite quantity of dry gas is inversely proportional to the pressure, provided the temperature remains constant."

The mathematical expression for Boyle's Law is:

PV = k

Where:
P is the pressure of the gas
V is the volume of the gas
k is a constant, and has units of force x distance

The value k is the result from the measurements of volume and pressure for a fixed quantity of gas multiplied together. After making a change to the system, typically by forcing a change in the volume of the vessel containing the fixed quantity of gas, the product of the new volume and new pressure will be equal to the original value of the constant, k.

Therefore:

P1V1 = P2V2

where:

P1 = original pressure
V1 = original volume
P2 = new pressure
V2 = new volume

In practice, this equation is solved for one of the two new quantities to determine the effect that a change in the other new quantity will have.

Example

If a change in volume was made to a known volume and pressure of a fixed quantity of gas, the equation can be rearranged so that the new pressure can be determined.

P1V1 = P2V2

P2 = (P1V1)/V2

before we get into the problem solving part, it is really really important to know the units of measurement for volume and pressure.

pressure is measured in...

~*pascals(Pa) - the number of Newtons per square metre of surface.

~*Kilopascals (kPa) - 1000pascals

~*millimetres of mercury (mmHg) - The height of a column of mercury on a Torricellian barometer, measured in mm.

~*atmospheres(atm) - Number of times greater than the mean pressure of the atmosphere at sea level

=> 1 atm = 760mmHg = 101kPa




Volume is measured in...

~* Litres(L) - yall know what that is

~* Millilitres(mL) - yall know what that is :P

==> 1L = 1000mL

there are others but they are not required in my article ^_^




Problem example

A sample of carbon dioxide has a volume of 240mL at a pressure of 101kPa and a temperature of 25 degrees celcius. What pressure is needed to reduce the volume to 60.0mL at 25 degrees celcius?

This is done in three simple steps

Step one: state Boyle's Law

P1V1 = P2V2

step two: write down the values

P1 = 101
V1 = 0.240
P2 = ?
V2 = 0.06

step three: : substitue the values into the formula and solve for the unknown value. (In this case, "P2")

101 x 0.24 = P2 x 0.6
P2 = (101 x 0.24)/0.6
P2 = 404kPa

Therefore, the pressure needed to reduce the volume to 60.0mL at 25 degrees celcius is 404kPa.




More Problems..
if u need help with the measurements, refer to what i said before about the units of measurements.

1. A sample of ammonia gas occupying 700mL has a pressure of 101kPa. If the temperature of the gas remains constant, what will be the volume of the sample if a pressure of 320kPa was applied?

2. At the surface of the water, the volume of the air trapped inside a balloon occupies 24L at 1 atmospheric pressure. If the balloon was forced underwater, at a constant temperature, what would be the pressure acting on the balloon for the volume to occupy 12L?

3. A cream gun charger containing carbon dioxide has a volume of 0.08L and a pressure of 650kPa. If the temperature remained constant, what volume would the carbon dioxide occupy if the charger were to be released into a 1L cream gun that was almost half way filled with cream, at 1 atmospheric pressure?

4. A sample of hydrogen occupies 5L at 760mmhg. At what pressure will the sample occupy 2L if the temperature remained constant?

5. An amount of oxygen occupies 50L at 760mmHg pressure. If the temperature remains constant, what volume will it occupy at 6 atmospheres pressure?

Boyle is so great becoz...

he dedicated his life to science, accomplished many great works, and made lots of important contributions to science.

"Touching the Spring of Air, and its Effects" is one of the most famous scientific works of Boyle.
He proved that gases were elastic, meaning that gases can be stretched and squeezed and it will spring back to its initial shape. He proved that air had weight at the surface of the earth and in response to his critics gave the scientific world the formula that now carries his name, Boyle's Law.
Not only is Boyle's Law very important in science, it is also very important outside of the laboratory and knowing these factors about gases even saves lives. Boyle's Law is very important in diving. Underwater, the lungs are under intense pressure, and so that drastically changes volume. A breath taken at the surface of a body of water is at 1 atmospheric pressure, about 101kPa.

Diving to a depth of 10 meters the pressure will double to around 202kPa. The volume of the lungs will be halved. A full breath of compressed air taken at 10m underwater will double in volume on the way back up to the surface. That is why exhaling on the return trip is required, or else the lungs will explode!

Boyle is a lifesaver, and so he truly is the worlds greatest Windbag.

And don't forget that Boyle was rich but he was not greedy; he was very generous and those around him benefited from his generosity.
He was a good man.

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