The Ideal Gas Law and the Patriots:A Winning Team!!!

Part 4 of our May MCAS cram series!

Before there was Tom Brady,there was Amedeo Avogadro!

Full name: Lorenzo Romano Amedeo Carlo Avogadro qi Quaregna e di Cerreto(1776-1856)Hometown: Turin, Italy

You already know one of his discoveries:

• Avogadro’s number:6.02 x 1023 (on your MCAS reference sheet). He did not actually discover it, but his theories led to it and it was named in his honor.• We use that number with the

mole. We define a mole two ways:

1. How many total molecules (ie. 1 mole of H2 gas = 6.02 x 1023 molecules)

2. How much mass (ie. 1 mole of H2 gas = 2 x 1.00794 g = 2.01588 g)

Avogadro’s Law!

When you blow into a balloon more and more, it expands. Why?The more you breath into a balloon, the more moles of your breath go into the balloon. The balloon’s volume must increase to hold all that gas.

Hence Avogadro’s Law (written in two ways):

n = number of moles (mol)k = constant, written in L/molStandard Temperature and Pressure:

k = 22.4 L/molAlso 1 atm (101.3 kPa) and 273°K

*Both are in your MCAS reference sheet.• Volume and moles are directly proportional.

They both go up and down together at the same rate.

The Ideal Gas Law• Scientists found that

most gases behave very alike at room temperature and pressure.

• Ideal gases should:– Not be affected by

intermolecular forces (not attract or repel)

– Be made up of particles that do not have any significant volume

– Not condense into liquid at room temperature

The Ideal Gas Law combines:• Boyle’s Law (pressure and volume)• Charles’ Law (volume and

temperature)• Avogadro’s Law (volume and moles)

The Ideal Gas Equation• V = in Liters (L)• n = in moles (mol)• T = in Kelvin (°K)• R is a constant that

depends on P being given as kPa (Kilopascals) or atm (atmospheres):

*The Ideal Gas Equation and R can both be found in your MCAS Reference sheet. Practice using them!

Two Superlaws: so who wins?Combined Gas Law

1. Can account for only three factors: Pressure, Volume, and Temperature.

2. Can be used with any gas.

Ideal Gas Law

1. Can account for four factors: Pressure, Volume, Temperature, and Moles!

2. Can only be used with ideal gases.

We are all winners because we have both laws to help us! Be sure to choose the correct one depending on the MCAS question. That way you can win again and again! Speaking of winners…

Ideal Gas Law in the sports news!By now you may have heard of “Deflategate.” If you haven’t, here’s a summary:1. In the 2015 AFC Championship game, a Colts

player intercepted a Tom Brady pass. The Colts noticed that Brady’s ball was very soft. He likes minimally soft balls, 12.5 psi, for passing. NFL rules say 12.5-13.5 psi. It was cold and rainy.

2. The NFL checked the pressure of both the Pats’ and Colts’ balls at halftime. The Pats’ balls’ pressure changes were too much compared to the Colts’. The NFL reinflated the Pats’ balls for the 2nd half.

3. The Pats won anyway, 45-7. They scored 17 points in the 1st half (with “illegal” balls) and 28 points in the 2nd half.

4. The Pats and Brady were accused of cheating for two weeks until their Super Bowl 49 victory.

5. The NFL, 3+ months later, suspended Brady 4 games and punished the Patriots for trying to cheat.

What does all that have to do with chemistry? The Ideal Gas Law!P = ball pressure, in psiV = ball volume (less volume, easier to throw in cold and wet weather)n = moles of air in the ballsR = ideal gas constantT = temperature inside the balls, and also at the game (outdoors, cold) and officials’ room (indoors, warm)

The Ideal Gas Law was used by both sides!The Wells Report

• According to the scientists hired by the NFL, if the balls were inflated/deflated to 12.5 psi before the game, following Ideal Gas Law, they would have been 11.32-11.52 psi by halftime.– Why would the balls deflate by themselves? It

was warm inside the officials’ room before kickoff (~70°F). It was cold at the field (~45°F). The air inside the balls would have contracted, and the NFL’s scientists accounted for that decrease in volume and pressure because of the cold.

• 8 out of 11 Pats balls measured by one of the officials had psi below 11.32.

• All 4 Colts balls were at 12.50 or above by the same official. Their balls’ psi did not drop as much as the Patriots’.

• Therefore, the NFL believed a Patriots staffer used a needle to over-deflate the balls before the game because Brady liked soft balls. So, they cheated.

WellsReportContext.com

• The Patriots’ lawyers launched their own website criticizing the Wells Report and the NFL’s penalties.

• Two officials measured both teams’ balls at halftime, and the other official found that 3 out of 4 Colts balls were below 12.5, and 8 out of 11 Pats balls were above 11.32 psi!

• How could this happen??? The officials used pressure gauges made by different companies! Not reliable!

• Therefore, the NFL ignored the Ideal Gas Law (after using it in the Report) and relied too much on cheap and inaccurate gauges.

To be continued in the sports news!

MCAS Cram (Day four)