Understanding Chemical Reactions and Equilibrium in Systems
1. If there is a chemical reaction within a system, this system cannot be a closed system.
False – A closed system does not exchange matter with its surroundings. Mass is conserved in a chemical reaction. Therefore, it is possible that a reaction happens within a closed system as long as no mass is exchanged with its surroundings.
2. If there is a chemical reaction within a system, this system cannot be in equilibrium.
False – It is possible for a system to be in equilibrium even if a chemical reaction is occurring. For a chemical reaction to be in equilibrium, the forward and reverse reaction rates must be equal, resulting in no net change in the concentrations of reactants and products over time. In other words, at a microscopic scale, reactions are still taking place, but the system’s macroscopic properties remain the same.
3. In a living cell, equilibrium and steady state are synonymous terms.
False – At equilibrium, there is no net flow of energy or matter into or out of a system. A living cell cannot be at equilibrium and survive. A system is at steady state when the parameters that define it remain constant, even though a constant flow of mass and energy occurs.
4. A system in equilibrium does not require energy input to maintain its condition, whereas a system in steady state often does.
True
5. A body is in steady state if the parameters that define it (i.e., mass, temperature, composition) do not change over time.
True
6. dX/dt is always equal to zero at steady state.
True – At steady state, the concentration of a given variable “X” does not change over time (its derivative with respect to time is zero).
7. A drug with an elimination half-life of 15 minutes in the blood will leave the body faster than a drug with a half-life of 5 minutes.
False – A drug with a half-life of 5 minutes is reduced by half every 5 minutes. Therefore, it will be cleared from the body more quickly than a drug with a 15-minute half-life, which takes longer to decrease in concentration.
8. A drug with a half-life of 15 minutes in the blood has a lower rate constant for elimination than a drug with a half-life of 5 minutes.
True – Half-life and rate constants are inversely proportional.
9. External respiration is driven by the pressure differences between the atmosphere and the alveoli, while internal respiration is driven by the pressure differences between the blood and the tissues.
True
10. Total lung capacity includes residual volume.
True
11. During inhalation, the diaphragm contracts and moves upwards to allow air into the lungs.
False – During inhalation, the diaphragm moves downward, increasing the volume of the lungs and creating negative pressure that allows air to flow into the lungs.
12. Dead space in the lungs refers to areas where gas exchange does not occur, such as the trachea and bronchi.
True
13. As the partial pressure of a gas increases, the concentration of that gas in the liquid decreases, according to Henry’s Law.
False – According to Henry’s Law, the partial pressure of a gas and its concentration in the liquid are directly proportional.
14. When O2 and N2 have the same partial pressure in a gas mixture, the concentration of O2 will be higher than the concentration of N2 in the liquids, according to their Henry’s law constants.
True – Henry’s Law constants for O2 and N2 are 1.3 x 10-3 and 6.1 x 10-4, respectively. Since Cgas = H * Pgas, the concentration will be lower when ‘H’ is smaller and ‘Pgas’ remains the same.
15. Hemoglobin saturation is higher in the pulmonary artery than in the pulmonary vein.
False – The hemoglobin saturation is lower in the pulmonary artery compared to the pulmonary vein.
16. Breathing faster (i.e., at a higher ventilation rate) will lower the amount of CO2 in the blood.
True
17. Breathing faster will lower the amount of O2 in the blood.
False – Breathing faster typically increases the amount of O2 in the blood.
18. Breathing faster will increase blood pH.
True – Alkalosis (pH > 7.42) is caused by an overabundance of bicarbonate (HCO3–) in the blood or a loss of acid from the blood (metabolic alkalosis), or by a low level of carbon dioxide in the blood that results from rapid or deep breathing (respiratory alkalosis).
19. Intravenously injecting NaHCO3 will lower blood pH.
False – The bicarbonate ion is a weak base and will cause blood pH to increase. From slides: Metabolic alkalosis treatment uses an intravenous (IV) line to deliver fluid and other substances, such as hydrochloric acid (HCl) infusion, to decrease [HCO3–].