Pressure-Volume Relationship (Boyle’s Law) What is the relationship of pressure and volume of a gas sample at a constant temperature?

When you capped the end of the syringe with a certain volume of air in it, then pushed the plunger – what happened to the volume of the air in the syringe? Why? What happened to the pressure inside of the syringe? Why?

Describe Pressure qualitatively (what causes it): Describe pressure quantitatively: (mathematically): In what units can pressure be described?

Describe Pressure qualitatively : Force and area interact to create pressure – as force goes up, so does pressure, but area or space goes down (ever feel under “pressure?”) Describe pressure quantitatively: (mathematically): Pressure = Force/Area In what units can pressure be described? 1atm = 760mmHg = 29.92 inHg = 101.3kPa

How can we describe pressure on a molecular level? (i.e. chemically)

How can we describe pressure on a molecular level? (i.e. chemically) Pressure can be described as the frequency at which atoms are hitting against the walls of a container. Higher pressures result in higher rates of collisions.

Atmospheric Pressure You have evolved under about 1 atm of pressure on each square meter of your body. What would happen to your body if you went under the ocean where the pressure increases dramatically? Why can a whale dive to very deep depths but if you pull a deep sea fish up it turns to goo? Deep Sea squid on a submersible subs “arm” deeper than 12,000 feet (over 2 miles down!) P= 5271 PSI or 36,342 kPa

Atmospheric Pressure (1 atm = 101.3 kPa) What observations from A.1 Properties of Gases Lab that showed evidence of atmospheric pressure? Test tube covered in plastic, when inverted did not spill. Atmospheric pressure against plastic was enough to hold liquid in tube. Plastic bottle w/ hole did not leak water because atmospheric pressure kept the water in.

PV Qualitative Predictions What causes the “pressure” in a syringe on a molecular level? What would happen to the pressure in this container if the volume inside increased? Why? What if it volume decreased? Why?

PV Quantitative Predictions The relationship between pressure and volume of gases is “inverse”: If pressure increases – volume decreases If volume increases – pressure decreases Formula for Boyle’s Law: P1V1 = P2V2 ( the product of the initial pressure and volume equal the product of the resultant pressure and volume)

Make a qualitative prediction Will the pressure inside a syringe be smaller or larger if the volume is reduced? Now – the volume stared at 6.0ml and was reduced to 5.0 ml – the initial pressure was 2.0 atm. Will the final pressure be greater or less than 2.0 atm?

Make a qualitative prediction Will the pressure inside a syringe be smaller or larger if the volume is reduced? Pressure will go up because there are the same amount of molecules in a smaller space. Now – the volume stared at 6.0ml and was reduced to 5.0 ml – the initial pressure was 2.0 atm. Will the final pressure be greater or less than 2.0 atm? Pressure will be greater than 2.0 atm because pressure will increase.

Make a quantitative prediction P1V1 = P2V2 (V1) Initial volume is 6.0 ml (P1) Initial pressure is 2.0 atm (V2) Resulting volume is 5.0 ml What is the resulting Pressure (P2)?

P1V1 = P2V2 Step 1: Define each variable and decide what you are solving for. Step 2: Set up the problem using the equation Step 3: Solve the equation

P1V1 = P2V2 Step 1: Define each variable and decide what you are solving for. (V1) Initial volume is 6.0 ml (P1) Initial pressure is 2.0 atm (V2) Resulting volume is 5.0 ml What is the resulting Pressure (P2)? Step 2: Set up the problem using the equation (6.0 ml)(2 atm) = (5.0 ml) (P2) Step 3: Solve the equation 12 ml* atm = 5.0 ml * P2 12 ml * atm = P2 5 ml P2 = 2.4 atm

Using Boyle’s Law: P1V1 = P2V2 (6.0 mL)(2 atm) = (5.0 mL) (P2) 12 mL * atm = 5.0 mL * P2 12 mL * atm = P2 5 mL P2 = 2.4 atm

Complete A.6 1-3 A weather balloon with a volume of 4200L at 1 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?

Bodies evolve to live in certain “pressures” – there are different adaptations for water, deep water and land. But what about space? What is the pressure in space and why? What would happen to a body in space?

Observe & Think: Why did the paper not move Observe & Think: Why did the paper not move? Why did the ruler not move when the paper was placed on it? https://www.youtube.com/watch?v=Z5x5BLzQKZI