ch1 ppt

• Analytical chemistry is a measurement science consisting of powerful ideas and methods that are useful in all fields of science and medicine.
• Analytical chemistry deals with methods for determining the chemical composition of samples of matter.
• Analytical chemistry is applied throughout industry, medicine, and all the sciences.
• Quantitative analytical measurements play a vital role in chemistry, biochemistry, biology, geology, physics, and the other sciences.
• Many scientists devote much time in the laboratory gathering quantitative information about systems that are important and interesting to them.
• Quantitative Analysis indicates the amount of each substance in a sample.
• Qualitative Analysis reveals the identity of the elements and compounds in the sample.
• Gravimetric methods determine the mass of the analyte or some compound chemically related to it.
• Volumetric method determines the volume of a solution containing sufficient reagent to react completely with the analyte.
• Electroanalytical methods involve the measurement of such electrical properties as voltage, current, resistance, and quantity of electrical charge.
• Spectroscopic methods are based on measurement of the interaction between electromagnetic radiation and analyte atoms or molecules or on the production of such radiation by analytes.
• Miscellaneous methods include mass-to-charge ratio, rate of radioactive decay, heat of reaction, rate of reaction, sample thermal conductivity, optical activity, and refractive index.
• One of the first questions to be considered in the selection process is the level of accuracy required.
• A second consideration related to economic factors is the number of samples to be analyzed.
• The complexity of the sample and the number of components in the sample always influence the choice of method to some degree.
• Sampling involves obtaining a small mass of a material whose composition accurately represents the bulk of the material being sampled.
• Sampling is frequently the most difficult step in an analysis and the source of greatest error.
• The final results of an analysis will never be any more reliable than the reliability of the sampling step.
• A material is heterogeneous if its constituent parts can be distinguished visually or with the aid of a microscope.
• An assay is the process of determining how much of a given sample is the material indicated by its name.
• We analyze samples and we determine substances.
• A buret is a precisely manufactured glass tube with graduations enabling you to measure the volume of liquid delivered through the stopcock (the valve) at the bottom.
• Drying is done in an oven at 110°C, some chemicals require other temperatures.
• Filtration is used in precipitates from gravimetric analyses, washed, and then dried.
• Pipets and syringes deliver known volumes of liquid, transfer pipets are calibrated to deliver one fixed volume, and the last drop does not drain out of the pipet and should not be blown out.
• Calibration of volumetric glassware to measure the volume is being done for greatest accuracy.
• Micropipets deliver volumes of 1 to 1,000 μL (1 μL = 10 -6 L), liquid is contained in the disposable polypropylene tip, which is stable to most aqueous solutions and many organic solvents except chloroform (CHCl3).
• A desiccator is a closed chamber containing a drying agent called a desiccant, the lid is greased to make an airtight seal, and desiccant is placed in the bottom beneath the perforated disk.
• Calibration is the process of measuring the actual quantity that corresponds to an indicated quantity on the scale of an instrument.
• A first-aid kit should be available in the lab.
• Dispose chemical waste properly and responsibly.
• An analytical balance uses electromagnetic force compensation to balance the load on the pan and shows a typical capacity of 100 – 200 g and a read-ability of 0.01– 0 .1 mg.
• A volumetric flask is calibrated to contain a particular volume of solution at 20°C when the bottom of the meniscus is adjusted to the center of the mark on the neck of the flask.
• Syringes come in sizes from 1 to 500 μL and have an accuracy and precision near 1%.
• In anticipation of splashes on your body or in your eyes, know where to find and how to operate the emergency shower and eyewash.
• Know how to operate the fire extinguisher and how to use an emergency blanket to extinguish burning clothes.
• To operate a buret, wash it with new solution, eliminate air bubble before use, drain liquid slowly, deliver a fraction of a drop near end point, read bottom of concave meniscus, estimate reading to 1/10 of a division, avoid parallax, and account for graduation thickness in readings.
• Feedback control systems are used in chemical analysis, the process of continuous measurement and control is often referred to as a feedback system, and the cycle of measurement, comparison, and control is called a feedback loop.
• Label all vessels to indicate what they contain.
• The critical functions of your lab notebook are to state what you did and what you observed, it should be understandable by a stranger.