Gas Laws

Gas Laws summarizes the general laws that describe how the volume of a gas changes in response to changes in pressure (P), temperature (T in Kelvin) or the number of moles (n). The ideal gas law, which combines Boyle’s law, Charles’s law and Avogadro’s law, is presented, with explanations of using it to solve gas-law problems. Mathematical rearrangements of the ideal gas law to determine density and molar mass are described along with the use of Dalton’s law of partial pressures to find the pressure of each gas in a mixture. Finally the chapter presents ideal gas law and reaction stoichiometry, Graham’s law of effusion, and basic notions of real gases and their deviation from the ideal gas laws.

Innovation in Teaching Methodology: Level of Student Acceptance of ‘Boyles Law Apparatus’ Teaching Aids in Thermodynamics Course

Boyle's law is used to explain the inverse relationship between pressure and the volume of gas at a constant temperature. This law states that when the pressured container is filled by increasing gas, thus the total volume will decrease. This research paper aims to study the level of student acceptance of teaching based on teaching aids (TA) Boyle's Law Apparatus (BLA) in the teaching and learning for the DJJ20063 Thermodynamics course. The questionnaire study was distributed to 66 respondents, namely Port Dickson Polytechnic‟s students of semester 2, Diploma in Mechanical Engineering program December 2019 session who involved in lectures where TA is used to give the students a clear vision in understanding the concept of Boyle Law in the topic of Perfect Gas. The data were analysed by using SPSS software through descriptive analysis statistics. The results of the study showed that the level of effectiveness of this TA is at a high level with an average mean score of 3.70 and standard deviation 0.447. Therefore, studies showed that the use of this teaching aids among students provides a better understanding, especially on the topic of Perfect Gas compared to teaching methods without the teaching aids that had been produced before. Through this method as well, the study found that students' interest and determination to deepen a lesson can be nurtured in more depth.

Development of 'Boyles Law Apparatus' Teaching Aids for Thermodynamics Course: Innovation in Teaching Methodology

Teaching aids are among the most important instruments in providing effective delivery results as well as the best understanding to students. Therefore, this teaching aid should also be in the Thermodynamics course and among the topics whose concept is quite difficult to understand by students is Boyles Law in the topic of Perfect Gas. Boyle's law is used to explain the inverse relationship between pressure and gas volume at a constant temperature. This law states that when the pressure of the container is filled with increasing gas, then the total volume will decrease. Boyles' Law on the topic of Perfect Gas is also one of the important topics and it is the basis in Thermodynamics. This paper is about the development of Boyle's Law Apparatus (BLA) teaching aids (TA) for the DJJ20063 Thermodynamics course at Port Dickson Polytechnic which is an apparatus that can explain to students related to the basic concepts of Boyle's Law. In addition, this teaching aids can also help lecturers in providing a better understanding to students who take Thermodynamics courses. The production of this tool is not only used by lecturers in the theory class but also this tool can also be used for practical needs in the laboratory. In conclusion, a suitable apparatus for explaining Boyle's Law to students has been successfully designed and developed. In this regard, hopefully the innovation of this teaching aids will be able to benefit all parties in improving the teaching and learning system, especially for Thermodynamics course.

A practical demonstration of Boyle’s Law

In A practical demonstration of Boyle’s Law Mike Gibson briefly explores his involvement in an experiment to test prototype respirators with the Altitude Research Section of the RAF Institute of Aviation Medicine.

Deep-diving pilot whales make cheap, but powerful, echolocation clicks with 50 µL of air

Echolocating toothed whales produce powerful clicks pneumatically to detect prey in the deep sea where this long-range sensory channel makes them formidable top predators. However, air supplies for sound production compress with depth following Boyle’s law suggesting that deep-diving whales must use very small air volumes per echolocation click to facilitate continuous sensory flow in foraging dives. Here we test this hypothesis by analysing click-induced acoustic resonances in the nasal air sacs, recorded by biologging tags. Using 27000 clicks from 102 dives of 23 tagged pilot whales (Globicephala macrorhynchus), we show that click production requires only 50 µL of air/click at 500 m depth increasing gradually to 100 µL at 1000 m. With such small air volumes, the metabolic cost of sound production is on the order of 40 J per dive which is a negligible fraction of the field metabolic rate. Nonetheless, whales must make frequent pauses in echolocation to recycle air between nasal sacs. Thus, frugal use of air and periodic recycling of very limited air volumes enable pilot whales, and likely other toothed whales, to echolocate cheaply and almost continuously throughout foraging dives, providing them with a strong sensory advantage in diverse aquatic habitats.

Optimized Volume Determinations and Uncertainties for Accurate and Precise Manometry

ABSTRACTPrecise manometric pressure, volume, and temperature (P-V-T) measurements of carbon in samples, standards, and blanks are critical for radiocarbon studies. While P and T uncertainties depend on instrument choice and environmental stability, V uncertainties depend on their method of measurement and are often overlooked. We used numerical simulations and error propagation to find optimum procedures for measuring “cold-finger” volumes equipped with capacitance diaphragm gauges (CDGs) by two common application of Boyle’s Law: cryogenic transfers and serial gas expansions with a reference flask of known volume. Minimum relative uncertainties of cold-finger volumes are comparable for these two methods (∼0.002), but the serial gas expansion method is preferred due to its convenience. Serial gas expansions can be performed to high precision by using dry air, an initial pressure ∼76% full-scale (e.g., 760 Torr), and a reference flask with an optimal volume based on preliminary estimates of cold-finger volumes and an empirical power function. The volumes of cold-fingers ≥ 12 cm3 can be determined with minimum achievable relative uncertainties of 0.0021 to 0.0023. This limit translates to minimum achievable relative uncertainties of 0.0026 to 0.0027 for P-V-T measurements of moles of gas simulated here.

Development and Testing of a Mobile Phone App for Risk Estimation of Gas Volume Expansion and Intraocular Pressure Elevation in Patients With Intravitreous Gas or Air Tamponade: Interobserver Assessment Study (Preprint)

BACKGROUND Pars plana vitrectomy (PPV) with intravitreous tamponade of gas or air has been widely used for a series of vitreoretinal diseases. It is estimated that 100,000 patients per year undergo PPV globally, and half of them were subsequently tamponaded with gas or air. According to Boyle’s law (P1V1=P2V2), patients with an intravitreous remnant of gas or air will be under high risk of intraocular pressure (IOP) elevation and subsequent vision loss owing to the expanded intravitreous gas or air when traveling post operation to a place with a significantly higher altitude. We always explain to patients why postoperative travel is potentially risky. Emergency cases of elevated IOP caused by postoperative traveling would sometimes come to surgeons. However, there have been few disease education or reference tools for both the surgeons and patients to have better communication. OBJECTIVE The aim of this study was to introduce and evaluate a mobile phone app developed by surgeons (the authors) for preliminary risk estimation of volume expansion and IOP elevation in patients with intravitreous gas or air when traveling to a place of higher altitude. METHODS The app was developed on the iOS and Android operating systems. Boyle’s law (P1V1=P2V2) was the theoretical basis of the app. Intravitreous gas or air volume and altitude values were independent factors to deduce the risk report. Consecutive patients underwent vitrectomy, and those with an intravitreous remnant of gas or air were recruited. The surgeons judged the vertical height of the fluid/gas interface through the dilated pupil; the patients were instructed to judge it according to their visual field when looking straight ahead and line it out on a chart included in the app. Finally, all the patients were required to fill a Likert scale–based questionnaire with 2 main items to evaluate the participants’ user experience and attitudes toward the app. RESULTS A total of 50 patients were included (30 males and 20 females). All patients could independently operate the app to complete the test. The median heights of the fluid/gas interface independently judged by the surgeon and patients were 40% (range: 10%-75%) and 41% (range: 9%-78%), respectively (P=.63). The median altitude of the participants’ destinations was 150.0 m (range: 0-3490 m). The Bland-Altman analysis revealed a good agreement between the surgeons’ and patients’ judgments (bias of −0.3%), with 95% limits of agreement of −5.8% to 5.3%. Overall, the Likert scale revealed a positive attitude from the patients toward the app. CONCLUSIONS The app is reliable for patients to have preliminary risk estimation of intravitreous gas or air volume expansion and IOP elevation if travel to a place of higher altitude is planned. The surgeons could also use it as a platform for better disease communication.