Question about Spectrophotometer?
That would be like trying to drive with a fogged up windshield. Normally, you can't see the windshield - because it doesn't interfere with the path of the light from outside before it enters your eye. But the particles (tiny water droplets) on the windshield scatter the light, resulting in a fuzzy picture for you, the driver. In a spectrometer, the sample solution is placed inside the cuvet, and a tiny spectrum light beam is shined through it. Some light is absorbed by the sample, and the rest is transmitted and hits the (also tiny) detector on the other side of the cuvet. The "absorbance" is basically the difference between the full spectrum of the beam, i.e., before it passes through the sample, and the detected light, i.e., after it passes through the sample. The cuvet itself isn't supposed to absorb any light, and normally it doesn't - but if it's dirty, that's a different situation. The oil/dirt particles will scatter (change the angle of travel of), and possibly absorb, some of the light. This will give a false reading. (a) Oil & dirt in the form of fingerprints certainly won't CREATE more light for the detector to see. But it will scatter and/or absorb some of the beam's light - which means that less will reach the detector. Remember that absorbance is light that doesn't reach the detector... (b) Beer's Law states that higher absorbance means higher concentration (A = ebC). (c) Kc is the equilibrium constant, and is basically products over reactants. I'm not sure exactly what your equation will be since I don't know what the experiment is. You will answer this question based on how the concentrations of the products and reactants will appear to change based on the effect of fingerprints on absorbance from (a) and (b).
EMPIRICAL FORMULA LAB: What could be the source of error in this lab?
I am conducting a lab for my chemistry class. The lab purpose is to determine the empirical formula of Silver Oxide. I started with the approximately same amount of Silver Oxide each time and follow the same procedures, but each time, I got a completely different empirical formula for Silver Oxide. The data that I've collected are: Trial 1: Silver Oxide: 0.521g Silver Metal: 0.354g Oxygen Gas: 0.167g Empirical formula: AgO3 Trial 2: Silver Oxide: 0.50g Silver Metal: 0.46g Oxygen Gas: 0.04g Empirical formula: Ag5O3 Trial 3: Silver Oxide: 0.50g Silver Metal: 0.45g Oxygen Gas: 0.05g Empirical formula: Ag4O3 What went wrong?
What kind of data is collected in Clinical Trials?
Safety data, such as labs (which may encompass any body fluid people produce, depending on the study), ECGs, physical exam results, vital signs, hearing tests, vision tests, neurological exams, pulmonary function tests and so forth, depending upon the disease/disorder in question; some of these tests may be done because of adverse events discovered during animal testing or adverse events of similar medications.Should a subject be hospitalized, become pregnant, develop cancer, or have some other "medically important" event, we gather all information related to the event (whether it is possibly related to the study or not) and report to the sponsor and our institutional review board within 24 hours of the researcher or other study personnel learning of the event.Efficacy data may include physical exam results, quality of life tests, clinician administered tests (particularly in psychiatric studies), and comparison of any safety data (see above) collected at the first visit.We also collect such things as study drug compliance, previous medical history, current and past medications, adverse events that occur during the study (whether they have anything to do with the drug or not...if someone attacks you at a bar and blacks your eye when you are in a study, that injury will be noted).In addition to data collected on patients, we collect data on the researchers involved at our site AND the study itself. There's study correspondence, medical licenses of any study personnel, duties of study personnel are noted, any laboratory certifications, continuing education (as regards to the study), information on the protocol, consent forms, HIPAA forms and other study documents (and any changes to those), paperwork for any errors we make -- such as errors in obtaining consent (have not made this one in 20+ years of doing this), subject non-compliance, having study visits out of window, medication errors (haven't done this one either, although sometimes my patients do), doing visit procedures out of order, loss of study drug by a subject...the list goes on and some of these I have no control over, but still have to report.
Why should air bubbles be removed from the buret tip?
If the volume of air in the tip remained constant and the bubble remained stationary in the tip, the bubble would be of no consequence. As long as you're subtracting the initial volume reading from the final volume reading, the amount delivered would still be correct if the above was true. Unfortunately, though, bubbles will tend to completely pop out when a large volume of liquid is being dispensed from the buret. Because the bubble occupies a significant volume in and of itself, if it came out of the tip during the course of dispensing, the actual volume delivered would be less than the volume reported. Due to the very likely possibility of this happening if a bubble is allowed to remain, it's best to go ahead and get rid of the bubbles before using the buret to dispense a measured volume of liquid.
What kind of jobs does an environmental engineer do? Does it involve a lot of lab work? And do they work with hazardous materials?
So environmental engineers usually require samples of air, water or soil to be tested to compare the results with regulatory standards. But, they usually would not do the actual testing of the samples. They may do the actual sampling.and deliver it to be tested. The testing may be done by either an accredited laboratory or by a chemist.Jobs that an environmental engineer can do are as follows:Water and Waste-water Treatment: design and management of water and wastewater plants. Wastewater may include both domestic and industrial effluent. So engineer may be fired to design a treatment plant or be hired to manage a plant.Solid and Hazardous Waste Management: Design of Landfill and waste management systems, recycling and dealing with hazardous waste.Air Pollution Control: designing of devices to mitigate air pollution in industrial settings and indoor air quality assessments.Transport of Pollutants: Designing stacks to ensure that the surrounding land is not affected adversely from the air emitted from the stack. Calculating the level of contamination at a distance from a pollutant source in air, water and soil.Environmental Impact Assessment ReportsManagement of Environmental Management Systems to ISO 14000 or any other standard.Advisory role in ensuring regulatory and legal compliance with environmental laws and standards)Disaster Management and Mitigation: making and implementing disaster management plans and dealing with health and safety.It is possible that an environmental engineer may have to work with hazardous materials, but this depends on what type of job they are doing. Environmental engineers deal with waste a lot, and a lot of waste is unsafe to humans and the environment. However once proper health and safety procedures are followed there should not be a problem. Not all jobs will have this issue but it is a possibility.