Cartesian Divers

Why do you think pumping the water gun makes the water that comes out of the gun travel further?

1. Observe a “Cartesian Diver”. Record your observations. 2. Summarize your observations about the effect of pressure on the volume of a gas.

 Go to p. 370 in your book and perform the activity.  Graph the results of the experiment.

 1. Define pressure.  2. What units are used to measure pressure?  3. What units are usually used to measure the volume of a gas?  4. State Boyle’s Law.  5. Determine the change in pressure if 1.0 L of gas at 1.0 atm was reduced to 0.25 L.  6. Give two practical applications of Boyle’s Law.  7. How did the pressure changes in the syringe affect the volume of gas in the syringe?  8. Draw and label a picture of the gas particles in the syringe at points A and B on the graph below.  9. The graph is one way to represent the observations that you made symbolically. An equation for that graph is another representation of the relationship. Write the mathematical equation that describes this relationship.

Example: Suppose you have a 1.0 L sample of oxygen gas at a pressure of 1.0 atm. If the pressure were increased to 2.0 atm, what would be the resulting volume? P 1 = 1.0 atm P 2 = 2.0 atm V 1 = 1.0 L V 2 = ? 1.0 atm × 1.0 L = 2.0 atm × (X) 1.0 = 2.0(X) L = V 2 Boyle’s Law Calculation

1. Determine the change in pressure if 1.0 L of gas at 1.0 atm was reduced to 0.25 L. 2. List two practical applications of Boyle’s Law.

1. What formula is used to calculate a new volume or pressure? 2. What are the units of measure for pressure? 3. What are some units for volume? 4. Do the units for P 1 and P 2 or V 1 and V 2 have to be the same? 5. What is STP?

1. a) Sketch a graph that shows a direct relationship between two variables. b) Sketch a graph that shows an inverse relationship between two variables. c) Which graph best depicts the relationship between pressure and volume? 2. What is the mathematical relationship for pressure and volume of a confined gas at constant temperature?

3. What pressure would be required to decrease the volume of a balloon from 1200cm 3 to 750 cm 3 if the original pressure was 1 atm? 4. If 1.5 L of gas in a balloon at 750 mmHg is allowed to expand at a constant temperature to 2.5 L, what will the resulting pressure be?

5. As the volume of a gas decreases and the temperature and quantity of gas remain constant, the pressure of the gas will ___________. 6. If 5.00 L of a gas at 1.20 atm has a change in pressure to 3.00 atm, what will the resulting volume be (assuming constant temperature)?

7. Divers get “the bends” if they come up too fast because gas in their blood expands, forming bubbles in their blood. If a diver has 0.05 L of gas in his blood under a pressure of 250 atm, then rises instantaneously to a depth where his blood has a pressure of 50.0 atm, what will the volume of gas in his blood be? Do you think this will harm the diver?

8. Submarines need to be extremely strong to withstand the extremely high pressure of water pushing down on them. An experimental research submarine with a volume of 15,000 liters has an internal pressure of 1.2 atm. If the pressure of the ocean breaks the submarine forming a bubble with a pressure of 250 atm pushing on it, how big will that bubble be?

9. Ammonia Gas occupies a volume of mL at a pressure of mmHG. What volume will it occupy at standard pressure? 10.A sample of Carbon Dioxide occupies a volume of 3500 milliters at 125 kPa pressure. What pressure would the gas exert if the volume was decreased to 2.00 liters?