1. Do Now: Reading on Edmodo Complete guided notes chart – column 1

2. Atmospheric Pressure

3. Atmospheric pressure
The pressure of the atmosphere is ~100kPa which is 1atm.
The conversion is:
1atm = 101.3kPa
Pressure is measured by a barometer (a device that measures atmospheric pressure)

4. A device filled with mercury in
a glass column (barometer)
At atmospheric pressure (1atm)
The height of the Hg is 760mm
So… 1atm = 760mmHg

5. Do now: prepare for Pressure quizlet
Do now: prepare for Pressure quizlet!!! Today’s Topic: Pressure-volume Behavior of Gases (Boyle’s Law)

6. Pressure-volume behavior of gases
Remember pushing on the syringe… you were able to compress the gas when you applied an outside pressure.
The more pressure applied….

7. As the volume became smaller, the gas particles collided more and increased the pressure.
Gas molecules are in constant random motion; gas pressure is caused by molecules colliding with the walls of the container.

8. Look at the following images… what is the relationship?
Inversely Proportional!

9. Boyle’s law Robert Boyle, English scientist studied gases.
Boyle’s Law – the pressure and volume of a gas sample at constant temperature are inversely proportional.
P1V1 = P2V2

10. Sample problem
A weather balloon with a volume of 4200 L at 1.0 atm is tested by placing it in a chamber and decreasing external pressure to 0.72 atm. What will be the final volume of the balloon?
P1 =
V1 =
P2 =
V2 =

11. 1. You buy helium gas in small pressurized cans to inflate party balloons. The can label indicates that the container delivers 7100 mL of helium gas at kPa pressure. The volume of the gas container is 492 mL.
Do you think that the initial pressure of helium gas inside the can before use is greater or less than kPa? Explain.
Calculate the initial pressure of helium gas inside the container.
Was your prediction in Question 1a correct?

12. 2. Two glass bulbs are separated by a closed valve (see Figure 2. 14)
2. Two glass bulbs are separated by a closed valve (see Figure 2.14). The 0.50-L bulb on the left contains a gas sample at a pressure of 6.0 atm. The 1.7-L bulb on the right is evacuated; it contains no gas:
Predict, in general, what will happen to the total volume of the gas sample if you open the middle valve. Explain.
Predict, in general, what will happen to the total pressure of the gas sample if you open the middle valve. Explain.
Calculate the actual pressure of the gas sample after the valve is opened.