Counting units

APPacaiUS. . a guasl-elastic light system was composed of a light (Union Giken, LS-601) equipped counting unit. Light source was... 

Gengraf 25 mg and 100 mg capsules in 30-count unit dose packages Eon cyclosporine 25 mg and 100 mg capsules in 30-count unit dose blisters... 

Coefficients also apply to a larger scale, in which the counting unit is the mole (there are 6.02 X 1023 molecules per mole of a compound), rather than individual molecules. Thus, this balanced equation also represents the reaction of six moles of glucose with six moles of water to produce one mole of glucose and six moles of oxygen. 

The mole is the chemist s counting unit. Working with the mole should be second nature to students, so let s review grams to mole calculations since they are very important in mass-mass stoichiometry and the balanced equations provides mole ratios not mass ratios. 

Chemists use the mole as a counting unit, just as you use the dozen as a counting unit. Instead of asking for 12 eggs, you ask for 1 dozen eggs. Similarly, chemists refer to 1 mol of carbon or 2 mol of iron. 

Florists often sell flowers, such as roses, carnations, and tulips, by the dozen. A dozen is a counting unit for 12 items. 

A pair is always two objects, a dozen is 12, a gross is 144, and a ream is 500. Can you think of any other counting units ... 

Each of the counting units shown in Figure 11-1 is appropriate for certain kinds of objects depending primarily on their size and the use they serve. But regardless of the object—boots, eggs, pencils, paper— the number that the unit represents is always constant. 

Chemists also need a convenient method for counting accurately the number of atoms, molecules, or formula units in a sample of a substance. As you know, atoms and molecules are extremely small. There are so many of them in even the smallest sample that it s impossible to actually count them. That s why chemists created their own counting unit called the mole. In the DISCOVERY LAB, you found that a mole of paper clips is an enormous number of items. 

You have learned that different kinds of representative particles are counted using the mole, hut so far you have applied this counting unit only to atoms of elements. Can you make similar conversions for compounds and ions If so, you will need to know the molar mass of the compounds and ions. 

Fig. 1 Descriptive scheme of the experimental setups for dengue virus detection. (A) Photon counting unit. (Al) Hamamatsu HC135-01 PMT Sensor Module. (A2) PMT fixation ring. (A3) Manual shutter (71430, Oriel). (A4) Fiber holder that prevents the movement of the fiber inside the photon counting unit. (A5) Fiber optic. (A6) Connection wire of PMT to computer. (A7) Electricity cable. (B) The outside handle of manual shutter that enables light access to the PMT. (C) Immobilization unit. (Cl) Fiber optic. (C2) lOOpl pipette tip. (C3) Conical tube cup. (C4) Point of fixation of fiber. (C5) Optical fiber core. (C6) Biorecognition elements according to MAC-ELISA chemiluminescent OFIS (Alias et al. 2009). (C7) Test samples. (E) Connection to computer...

H.V. Power Supply Photon Counting Unit Prescalar... 

However, the mole is not just a counting unit like the dozen, which specifies only the number of objects. The definition of the mole specifies the number of objects in a fixed mass of substance. Therefore, 1 mole of a substance represents a fixed number of chemical entities and has a fixed mass. To see why this is important, consider the marbles in Figure 3.1 A, which we ll use as... 

What advantage is there to using a counting unit (the mole) in chemistry rather than a mass unit ... 

To proceed further, three major approximations to the theory are made [44] First, that the transition operator can be written as a pairwise summation of elements where the index I denotes surface cells and k counts units of the basis within each cell second, that the element is independent of the vibrational displacement and, third, that the vibrations can all be treated within the harmonic approximation. These assumptions yield a form for w(kf, k ) which is equivalent to the use of the Bom approximation with a pairwise potential between the probe and the atoms of the surface, as above. However, implicit in these three approximations, and therefore also contained within the Bom approximation, is the physical constraint that the lattice vibrations do not distort the cell, which is probably tme only for long-wavelength and low-energy phonons. 

FIGURE 4-5 Precision clock circuit. Each decade counting unit divides the frequency at its input by exactly 10. The accuracy of each output frequei cy is equal to that of the crystal oscillator. 

Counting large numbers of items is easier when you use counting units such as decades or dozens. Chemists use a counting unit called the mole. 

I Relate the mole to a common everyday counting unit. 

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