Basic unit conversions

The basic unit conversions are presented in Table 1.16. An electronic conversion table is also included in this chapter. 

A converter unit is used for the control of d.c. machines and also to provide a d.c. source to an inverter unit controlling an a.c. machine. In d.c. drives the d.c. voltage after tlie converter unit should be variable, whereas for in a.c. drive it is kept fixed. The voltage is varied by the invener unit. A convener unit is the basic power conversion scheme to convert an a.c. supply to a d.c. supply. Conventionally they are also known us rectifier units and c in be arranged in four different modes to suit dilTerent applications of a motor as follows ... 

Chemical Flowsheet Basic unit operation selection with flow rates, conversion factors, temperatures, pressures, solvents and catalyst selection Process synthesis route Laboratory and pilot scale trials Knowledge of existing processes... 

Basic study skills needed to study chemistry Macroscopic and microscopic properties of matter The SI (Metric) system Basic problem solving techniques Unit Conversion Method Significant figures... 

Chemistry is full of calculations. Our basic goal is to help you develop the knowledge and strategies you need to solve these problems. In this chapter, you will review the Metric system and basic problem solving techniques, such as the Unit Conversion Method. Your textbook or instructor may call this problem solving method by a different name, such as the Factor-Label Method and Dimensional Analysis. Check with your instructor or textbook as to for which SI (Metric) prefixes and SI-English relationships will you be responsible. Finally, be familiar with the operation of your calculator. (A scientific calculator will be the best for chemistry purposes.) Be sure that you can correctly enter a number in scientific notation. It would also help if you set your calculator to display in scientific notation. Refer to your calculator s manual for information about your specific brand and model. Chemistry is not a spectator sport, so you will need to Practice, Practice, Practice. 

In Tables n. 1 —11.20, several basic units and the basic conversion factors (CF) are presented. 

Finally, Appendices I and II are structured so that the reader can easily find some basic properties of environment-related compounds and unit conversions, or smartly estimate some parameters found in relationships in the rest of the book. The Appendix does not cover all cases and compounds however, it is a fust and separate guide provided to the reader for the basic calculations and properties found in this book. 

Temperature units/conversions Periodic table Basic atomic structure Quantum mechanical model Atomic number and isotopes Atoms, molecules, and moles Unit conversions Chemical equations Stoichiometric calculations Week 3 Atmospheric chemistry... 

The conversion of methanol into olefins is similar to the commercially proven methanol to gasoline (MTG) which was commercialised using natural gas as the feedstock in New Zealand. The variant generally uses similar catalysts to produce light olefins only, rather than the iso-paraffins and aromatics of the MTG process. This leads to the prospect of coal or gas conversion into resins (solids). These high value products may be easier to transport and sell than liquid fuels Figure 11.6 illustrates the basic unit operations for the process. 

In summary, if you can do all your work in SI, you need never be concerned about force-mass conversions (N = kg m/s ) or energy conversions (J = N-m=W s). If you are confronted with problems (or literature, or current U.S. legal definitions) involving the kgf, Ibf, cal, kcal, or Btu, you must follow the rules outlined above Always write down the dimensions, treat the dimensions as algebraic quantities, and multiply by 1 as often as needed to get the quantities into the desired set of units, using the appropriate values of the force-mass conversion factor and the thermal-mechanical energy conversion factor. Even in SI, if you stray from the basic units (m, kg, s, A, K, mol, and cd), you will need conversion factors such as... 

The basic units are those into which all values are converted when a calculation is conducted (kg for mass-bound substances and kJ for forms of energy). To facilitate the comparability with the inventory data, entry units were defined using a conversion formula and established as display units. In the inventory (Table 3.2) most of the substances were expressed in kg except for water and gas-oil, for which volume display units (m water and m gasoil, respectively) were defined using the density as conversion factor. Similarly, kWh was selected as display unit for electricity, wind power, and natural gas. 

I ve organized the topics in a logical progression — basically the same way I organize my courses for non-science and elementary education majors. I ve included a couple chapters on environmental chemistry — air and water pollution — because those topics appear so often in the news. And I ve included some material in appendices that I think might help you — especially Appendix C on the unit conversion method of working problems. 

The basic unit of length in the SI system is the meter (m). A meter is a little longer than a yard there are 1.094 yards in a meter, to be exact. But that s not a really useful conversion. The most useful Sl/English conversion for length is... 

The basic unit of mass in the SI system for chemists is the gram (g). And the most useful conversion for mass is... 

The basic unit for volume in the SI system is the liter (L). The most useful conversion is... 

That s why you need to know about the unit conversion method, which is sometimes called the factor label method. It will help you set up chemistry problems and calculate them correctly. Two basic rules are associated with the unit conversion method ... 

The RTG basic units include the radiation heat source (RHS), thermoelectric unit (TEU), radiation shielding (RS), and radiator. (Space systems need radiators also to cool them.) RTGs merits are determined by the following unique properties spontaneous release of thermal power, its direct conversion into electricity, a simple design, high-energy output, a long lifetime, the opportunity of employment practically in all scopes of activities under water, at the surface of the Earth and planets, and in space. 

Most tables of conversion factors do not include conversions between cubic units, but we can derive them from the conversion factors for the basic units. We cube both sides of the preceding equality to obtain the proper conversion factor. 

Contents Basic mathematical facts and figures. - Units, conversion factors and constants. - Spectroscopy and atomic stmcture. - Basic wave mechanics. - Facts, figures and data useful in the laboratory. 

Radioactive decay of nuclei is a first-order reaction decay rate (activity A) is therefore dependent on the concentration (content) of the radionuclide and is the product of this concentration (more precisely, the number of atoms of radionuclide N) and the decay constant X (in s" ) A =-(dN/dt) = X.N. The basic unit of activity, according to the System International (SI system) is the Bq (becquerel). One Bq (in s ) is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. Previously, the frequently used unit was the Ci (curie) defined as 3.7 x 10 decays per second. For conversion, the following relationship can be used 1 Ci = 3.7 x lO Bq. Number of radionuclide atoms transformed in time t is f T=NQ.e", where Nq is the initial number of atoms of the radionuclide at the time t=0. During conversion, the number of radioactive atoms of the radioactive nuclide is continuously decreasing. Combining both equations we get the relation expressing the dependence of activity on time A = -(dN/dt) The... 

The second reason for imperfect use of Mathcad capabilities is from a group of Mathcad users who do not use units justifying such decision with the idea that their quantities expressed in the basic units of one unit system (for example, in SI) and they have no difficulties with unit conversion. This reinforcing this notion is that without units Mathcad worksheets are simpler to compile to environment of the programming languages (such as C++, Fortran, etc), for conversion of customized functions into built-in DLLs (Dynamic-linked Libraries). The third reason is of major importance. It is connected with some peculiarities and limitations of tmit tool that cause a skilled user to extract units from a worksheet, almost finished, and turn them into comments instead of... 

---