Certified Hyperbaric Technologist Test CHT Hyperbaric Physics and Gas Laws 2 — Questions and Answers
Question 1: A sealed flexible bag holds 6 L of gas at the surface (1 ATA). At 3 ATA in a hyperbaric chamber, what is its approximate volume, assuming constant temperature?
- 2 L (Correct answer)
- 6 L
- 12 L
- 18 L
Correct answer: 2 L
Boyle's Law gives V2 = (P1V1)/P2 = (1 x 6)/3 = 2 L.
Question 2: Which gas law best explains why nitrogen narcosis worsens as a diver or chamber occupant goes deeper?
- Charles's Law
- Henry's Law (Correct answer)
- Graham's Law
- Boyle's Law
Correct answer: Henry's Law
Henry's Law states the amount of gas dissolved in tissue rises with partial pressure, increasing nitrogen's narcotic effect.
Question 3: At 2 ATA, what is the partial pressure of oxygen in air (21% O2)?
- 0.21 ATA
- 0.42 ATA (Correct answer)
- 1.0 ATA
- 2.0 ATA
Correct answer: 0.42 ATA
Partial pressure = fraction x total pressure = 0.21 x 2 = 0.42 ATA.
Question 4: Dalton's Law of partial pressures states that the total pressure of a gas mixture equals what?
- The product of the individual gas pressures
- The sum of the partial pressures of each gas (Correct answer)
- The pressure of the most abundant gas
- The average of the individual gas pressures
Correct answer: The sum of the partial pressures of each gas
Dalton's Law: total pressure is the sum of each gas's partial pressure.
Question 5: Why does a sealed rigid gas cylinder show increased pressure when moved from a cold storage room into a warm chamber?
- Boyle's Law
- Gay-Lussac's Law (Correct answer)
- Henry's Law
- Graham's Law
Correct answer: Gay-Lussac's Law
Gay-Lussac's Law states pressure is directly proportional to absolute temperature at constant volume.
Question 6: Approximately how much does ambient pressure increase for every 33 feet of seawater depth?
- 0.5 ATA
- 1 ATA (Correct answer)
- 2 ATA
- 3 ATA
Correct answer: 1 ATA
Each 33 fsw adds approximately 1 ATA to ambient pressure.
Question 7: A patient breathing 100% oxygen at 2.4 ATA receives an inspired oxygen partial pressure of approximately what?
- 0.24 ATA
- 1.0 ATA
- 2.4 ATA (Correct answer)
- 4.8 ATA
Correct answer: 2.4 ATA
With FiO2 of 1.0, PO2 = 1.0 x 2.4 = 2.4 ATA.
Certified Hyperbaric Technologist Test CHT Hyperbaric Physics and Gas Laws 2
A sealed flexible bag holds 6 L of gas at the surface (1 ATA).
At 3 ATA in a hyperbaric chamber, what is its approximate volume, assuming constant temperature?